feat(vat): add per-account declaration treatments (#1588)

Closes #1457
2026-08-13 17:03:35 +02:00
parent 7881f757a9
commit d02fd82191
32 changed files with 1196 additions and 253 deletions
@@ -932,3 +932,5 @@ One line per decision: `[YYYY-MM-DD] <decision>: <why>`. Appended by agents and
 [2026-08-13] WhatsApp decline observability (#1552) reuses whatsapp_messages with content-free rows for unknown-sender declines instead of a new table or aggregate RPC: no migration (no orphan risk), the wamid unique index gives redelivery dedupe for free (a redelivered bad-code or greeted message no longer earns a second reply), and the existing 30-day unknown-sender retention pass already deletes the rows. Write amplification from an over-quota flood is bounded by a 20-rows-per-hash-per-day trace cap, not by dropping the trail entirely. The settings panel gets a closed event enum derived server-side (lib/last-event.ts), never raw error_message text, so internal errors cannot leak to the client.
 [2026-08-13] Issue #546 ships a provider-agnostic Peppol BIS Billing 3 XML export with strict Swedish preflight, not a fake send path: certified access-point delivery, SMP lookup, receipts, inbound handling, credentials, and commercial terms depend on Emil selecting and contracting a multitenant provider, and the existing email delivery state cannot truthfully model those guarantees.
 [2026-08-13] Kontantmetoden year-end VAT supersedes the 2026-08-06 VAT-reporting premise: BAS 2618/2628/2638 and 2648 feed the final declaration, reverse-charge purchases include both VAT sides and their basis, and only the mechanical day-one reversal is excluded from later VAT periods. Skatteverket requires unpaid invoice VAT in the final period and warns against reporting it twice after year end.
+[2026-08-13] Per-account VAT treatment is class-aware and explicit values override the static BAS mapping; SIE #SRU and #KTYP never supply it because they encode tax-return fields and account class, not momsdeklaration treatment.
+[2026-08-13] Per-account VAT treatment is class-aware; explicit values extend custom accounts while canonical accounts keep their static BAS momsdeklaration mapping. SIE #SRU and #KTYP never supply it because they encode tax-return fields and account class, not momsdeklaration treatment. VMB carries no default account rate because its VAT base is the margin, not gross sales.
@@ -62,6 +62,11 @@ import type {
  ImportResult,
  ParseIssue,
 } from '@/lib/import/types'
+import {
+  applyVatTreatmentReview,
+  enrichAccountMappingsWithVat,
+} from '@/lib/import/account-vat-treatment'
+import type { AccountVatTreatment } from '@/lib/vat/account-vat-treatment'
 import type { TheaterModel } from '@/lib/import/theater-model'

 /** Above this size the client-side theater parse is skipped (main-thread
@@ -513,7 +518,11 @@ function SIEImportWizard() {

  // Skip the mapping step when all accounts are already mapped
  const hasUnmapped = mappings.some((m) => !m.targetAccount)
-  const sieSteps: ImportWizardStep[] = hasUnmapped
+  const needsVatReview = mappings.some((m) =>
+    m.requiresVatTreatmentReview && !m.vatTreatmentReviewed
+  )
+  const showMappingStep = hasUnmapped || needsVatReview
+  const sieSteps: ImportWizardStep[] = showMappingStep
    ? ['upload', 'preview', 'mapping', 'review', 'result']
    : ['upload', 'preview', 'review', 'result']

@@ -589,7 +598,6 @@ function SIEImportWizard() {
        issues: data.parsed.issues,
        stats: data.parsed.stats,
      })
-      setMappings(data.mappings)
      setPreview(data.preview)
      setIssues(data.parsed.issues)
      setSieAccounts(data.parsed.accounts)
@@ -597,7 +605,11 @@ function SIEImportWizard() {
      const accountsRes = await fetch('/api/bookkeeping/accounts')
      if (accountsRes.ok) {
        const accountsData = await accountsRes.json()
-        setBasAccounts(accountsData.data || [])
+        const accounts = accountsData.data || []
+        setBasAccounts(accounts)
+        setMappings(enrichAccountMappingsWithVat(data.mappings, accounts))
+      } else {
+        setMappings(enrichAccountMappingsWithVat(data.mappings, []))
      }

      setStep('preview')
@@ -711,6 +723,27 @@ function SIEImportWizard() {
    })
  }, [mappings])

+  const handleVatTreatmentChange = useCallback((
+    sourceAccount: string,
+    treatment: AccountVatTreatment | null,
+    rate: number | null,
+  ) => {
+    setMappings((prev) => applyVatTreatmentReview(prev, sourceAccount, treatment, rate))
+  }, [])
+
+  const confirmVatReview = useCallback(() => {
+    if (mappings.some((mapping) =>
+      mapping.requiresVatTreatmentReview && !mapping.vatTreatmentReviewed
+    )) {
+      setError('Granska momshanteringen för alla markerade konton innan du fortsätter.')
+      return
+    }
+    setStep('review')
+    setError(null)
+    setValidationErrors([])
+    setValidationWarnings([])
+  }, [mappings])
+
  const missingAccounts = mappings
    .filter((m) => !m.targetAccount)
    .map((m) => ({ number: m.sourceAccount, name: m.sourceName }))
@@ -738,11 +771,11 @@ function SIEImportWizard() {

      // Optimistically update mappings: mark created accounts as self-mapped
      const createdSet = new Set(missingAccounts.map(a => a.number))
-      setMappings(prev => prev.map(m =>
+      setMappings(prev => enrichAccountMappingsWithVat(prev.map(m =>
        !m.targetAccount && createdSet.has(m.sourceAccount)
          ? { ...m, targetAccount: m.sourceAccount, targetName: m.sourceName, confidence: 1.0 }
          : m
-      ))
+      ), basAccounts))
      setPreview(prev => {
        if (!prev) return prev
        const newMapped = prev.mappingStatus.mapped + createdSet.size
@@ -760,14 +793,16 @@ function SIEImportWizard() {
      const accountsRes = await fetch('/api/bookkeeping/accounts')
      if (accountsRes.ok) {
        const accountsData = await accountsRes.json()
-        setBasAccounts(accountsData.data || [])
+        const accounts = accountsData.data || []
+        setBasAccounts(accounts)
+        setMappings(prev => enrichAccountMappingsWithVat(prev, accounts))
      }
    } catch (err) {
      toast({ title: 'Kunde inte skapa konton', description: err instanceof Error ? getErrorMessage(err) : 'Försök igen.', variant: 'destructive' })
    } finally {
      setIsCreatingAccounts(false)
    }
-  }, [missingAccounts, toast])
+  }, [basAccounts, missingAccounts, toast])

  const handleExecuteImport = useCallback(async (options: ImportExecuteOptions) => {
    if (!file) { setError('No file selected'); return }
@@ -887,11 +922,12 @@ function SIEImportWizard() {
      {step === 'preview' && preview && (
        <SIEPreviewStep preview={preview} issues={issues} missingAccounts={missingAccounts}
          onCreateAccounts={handleCreateAccounts} isCreatingAccounts={isCreatingAccounts}
-          onContinue={() => goToStep(hasUnmapped ? 'mapping' : 'review')} onBack={goBack} />
+          onContinue={() => goToStep(showMappingStep ? 'mapping' : 'review')} onBack={goBack} />
      )}
      {step === 'mapping' && (
        <AccountMappingStep mappings={mappings} basAccounts={basAccounts}
-          onMappingChange={handleMappingChange} onContinue={() => goToStep('review')} onBack={goBack} />
+          onMappingChange={handleMappingChange} onVatTreatmentChange={handleVatTreatmentChange}
+          onContinue={confirmVatReview} onBack={goBack} />
      )}
      {step === 'review' && preview && (
        <ImportReviewStep preview={preview} mappings={mappings}
@@ -900,7 +936,12 @@ function SIEImportWizard() {
      )}
      {step === 'result' && importResult && (
        <ImportResultStep result={importResult} onNewImport={handleNewImport} onUndo={handleUndo}
-          preview={preview} theaterModel={theaterModel} />
+          preview={preview} theaterModel={theaterModel}
+          unresolvedVatAccountCount={mappings.filter((mapping) =>
+            mapping.sourceAccount === mapping.targetAccount &&
+            ['3', '4', '5', '6'].includes(mapping.sourceAccount.charAt(0)) &&
+            !mapping.vatTreatmentReviewed
+          ).length} />
      )}
    </div>
  )
@@ -4,6 +4,7 @@ import { validateBody } from '@/lib/api/validate'
 import { sparsePatchBody } from '@/lib/api/sparse-patch'
 import { UpdateAccountSchema } from '@/lib/api/schemas'
 import { getErrorMessage as getUserErrorMessage } from '@/lib/errors/get-error-message'
+import { isVatTreatmentValidForAccountClass } from '@/lib/vat/account-vat-treatment'

 // DELETE hard-deletes an unused, non-system account; accounts referenced by
 // this company's journal entries must be deactivated instead (PUT is_active).
@@ -95,7 +96,7 @@ export const PUT = withRouteContext(
    // .default() today, so sparsePatchBody is a no-op here: it is the
    // structural guarantee that adding one later cannot make a PUT that
    // renames an account also rewrite its VAT code or SRU mapping. An
-    // explicit null (clearing sru_code, default_vat_code, default_vat_rate)
+    // explicit null (clearing sru_code, VAT defaults, or descriptions)
    // still survives.
    const validation = await validateBody(request, sparsePatchBody(UpdateAccountSchema), {
      log,
@@ -104,6 +105,19 @@ export const PUT = withRouteContext(
    if (!validation.success) return validation.response
    const body = validation.data

+    if (
+      body.default_vat_treatment &&
+      !isVatTreatmentValidForAccountClass(
+        body.default_vat_treatment,
+        Number(number.charAt(0)),
+      )
+    ) {
+      return NextResponse.json(
+        { error: 'Momshanteringen är inte giltig för kontoklassen' },
+        { status: 400 },
+      )
+    }
+
    if (Object.keys(body).length === 0) {
      return NextResponse.json({ error: 'Inget att uppdatera' }, { status: 400 })
    }
@@ -267,6 +267,28 @@ describe('POST /api/bookkeeping/accounts', () => {
    }
    expect(insertArg?.default_vat_rate).toBe(0)
  })
+
+  it('forwards default_vat_treatment into the insert', async () => {
+    const { supabase, calls } = createCapturingSupabase([{
+      data: { account_number: '4056', default_vat_treatment: 'reverse_charge_eu_goods' },
+    }])
+    auth(supabase)
+    const req = createMockRequest('/api/bookkeeping/accounts', {
+      method: 'POST',
+      body: {
+        account_number: '4056',
+        account_name: 'Inköp varor EU',
+        account_type: 'expense',
+        normal_balance: 'debit',
+        default_vat_treatment: 'reverse_charge_eu_goods',
+      },
+    })
+    expect((await createPOST(req, routeParams)).status).toBe(200)
+    const insertArg = calls.find((c) => c.method === 'insert')?.args[0] as {
+      default_vat_treatment?: string | null
+    }
+    expect(insertArg.default_vat_treatment).toBe('reverse_charge_eu_goods')
+  })
 })

 describe('DELETE /api/bookkeeping/accounts/[number]', () => {
@@ -376,6 +398,33 @@ describe('PUT /api/bookkeeping/accounts/[number]', () => {
    expect(updateArg?.default_vat_rate).toBe(0)
  })

+  it('forwards default_vat_treatment into the update', async () => {
+    const { supabase, calls } = createCapturingSupabase([{
+      data: { account_number: '3041', default_vat_treatment: 'standard_25' },
+    }])
+    auth(supabase)
+    const req = createMockRequest('/api/bookkeeping/accounts/3041', {
+      method: 'PUT',
+      body: { default_vat_treatment: 'standard_25' },
+    })
+    expect((await PUT(req, { params: Promise.resolve({ number: '3041' }) })).status).toBe(200)
+    const updateArg = calls.find((c) => c.method === 'update')?.args[0] as {
+      default_vat_treatment?: string | null
+    }
+    expect(updateArg.default_vat_treatment).toBe('standard_25')
+  })
+
+  it('rejects a VAT treatment that does not apply to the account class', async () => {
+    const { supabase, calls } = createCapturingSupabase([])
+    auth(supabase)
+    const req = createMockRequest('/api/bookkeeping/accounts/5010', {
+      method: 'PUT',
+      body: { default_vat_treatment: 'standard_25' },
+    })
+    expect((await PUT(req, numberParams)).status).toBe(400)
+    expect(calls.some((call) => call.method === 'update')).toBe(false)
+  })
+
  // The body is spread straight into .update(), so the write set must be
  // exactly what the caller named. UpdateAccountSchema carries no .default()
  // today; these two lock the property in so adding one cannot turn a rename
@@ -104,6 +104,7 @@ export const POST = withRouteContext(
        description: body.description || null,
        default_vat_code: body.default_vat_code || null,
        default_vat_rate: body.default_vat_rate ?? null,
+        default_vat_treatment: body.default_vat_treatment ?? null,
        sru_code: body.sru_code || null,
        sort_order: parseInt(body.account_number),
      })
@@ -31,10 +31,19 @@ function buildSupabase(
  chartAccounts: Array<{
    account_number: string
    account_name?: string
+    account_class?: number
    default_vat_rate: number | null
+    default_vat_treatment?: string | null
  }> = []
 ): SupabaseShape {
-  const chartResult = { data: chartAccounts, error: null }
+  const chartResult = {
+    data: chartAccounts.map((account) => ({
+      account_class: 3,
+      default_vat_treatment: null,
+      ...account,
+    })),
+    error: null,
+  }
  return {
    rpc: vi.fn().mockResolvedValue(linesResult),
    from: vi.fn().mockImplementation((table: string) => {
@@ -44,6 +53,8 @@ function buildSupabase(
        return {
          select: vi.fn().mockReturnThis(),
          eq: vi.fn().mockReturnThis(),
+          gte: vi.fn().mockReturnThis(),
+          lte: vi.fn().mockReturnThis(),
          in: vi.fn().mockReturnThis(),
          not: vi.fn().mockReturnThis(),
          order: vi.fn().mockReturnThis(),
@@ -228,7 +239,7 @@ describe('GET /api/reports/vat-declaration/ruta/[ruta]/sources', () => {
  })
 })

-describe('GET /api/reports/vat-declaration/ruta/[ruta]/sources: ruta 05 accounts', () => {
+describe('GET /api/reports/vat-declaration/ruta/[ruta]/sources: account overrides', () => {
  /** The p_accounts array the route handed to get_vat_ruta_source_lines. */
  function rpcAccounts(supabase: SupabaseShape): string[] {
    return (supabase.rpc.mock.calls[0][1] as { p_accounts: string[] }).p_accounts
@@ -280,7 +291,23 @@ describe('GET /api/reports/vat-declaration/ruta/[ruta]/sources: ruta 05 accounts
    const accounts = rpcAccounts(supabase)
    expect(accounts).toContain('2611')
    expect(accounts).not.toContain('3013')
-    expect(supabase.from).not.toHaveBeenCalledWith('chart_of_accounts')
+    // Every ruta resolves explicit account overrides before the static BAS
+    // fallback, but a ruta 05-only custom account still stays out of ruta 10.
+    expect(supabase.from).toHaveBeenCalledWith('chart_of_accounts')
+  })
+
+  it('drills into a custom EU purchase account in ruta 20', async () => {
+    const supabase = buildSupabase({ data: [], error: null }, { data: null, error: null }, [{
+      account_number: '4056',
+      account_name: 'Inköp varor 25% EU',
+      account_class: 4,
+      default_vat_rate: 0.25,
+      default_vat_treatment: 'reverse_charge_eu_goods',
+    }])
+    authOk(supabase)
+
+    expect((await get('20')).status).toBe(200)
+    expect(rpcAccounts(supabase)).toContain('4056')
  })
 })

@@ -4,7 +4,7 @@ import {
  ACCOUNT_RUTA,
  resolvePeriodDates,
 } from '@/lib/reports/vat-declaration'
-import { fetchDynamicRuta05Accounts } from '@/lib/reports/vat-revenue-accounts'
+import { fetchDynamicVatAccounts } from '@/lib/reports/vat-revenue-accounts'
 import type { ReportSourceLine } from '@/lib/reports/source-lines'
 import type { VatDeclarationRutor, VatPeriodType } from '@/types'

@@ -40,17 +40,17 @@ export const GET = withRouteContext<{ params: Promise<{ ruta: string }> }>(
    rutaParam.startsWith('ruta') ? rutaParam : `ruta${rutaParam}`
  ) as keyof VatDeclarationRutor

-  // Invert ACCOUNT_RUTA: which BAS accounts feed this ruta?
+  const dynamicVatAccounts = await fetchDynamicVatAccounts(supabase, companyId)
+
+  // Invert the effective mapping. Fixed BAS mappings stay authoritative;
+  // explicit treatments add custom accounts only.
  const accountsForRuta = Object.entries(ACCOUNT_RUTA)
    .filter(([, m]) => m.box === rutaKey)
    .map(([acc]) => acc)

-  // Ruta 05 also collects the company's own momspliktiga intäktskonton, which
-  // ACCOUNT_RUTA cannot know about (#1261). Without them the drill-down would
-  // list a smaller sum than the figure it drills into.
-  if (rutaKey === 'ruta05') {
-    const { accounts } = await fetchDynamicRuta05Accounts(supabase, companyId)
-    accountsForRuta.push(...accounts)
+  for (const [account, mapping] of dynamicVatAccounts.mappingByAccount) {
+    if (ACCOUNT_RUTA[account]) continue
+    if (mapping.box === rutaKey) accountsForRuta.push(account)
  }

  if (accountsForRuta.length === 0) {
@@ -0,0 +1,52 @@
+'use client'
+
+import { useTranslations } from 'next-intl'
+import { Label } from '@/components/ui/label'
+import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from '@/components/ui/select'
+import {
+  vatTreatmentsForAccountClass,
+  type AccountVatTreatment,
+} from '@/lib/vat/account-vat-treatment'
+
+interface AccountVatTreatmentSelectProps {
+  value: AccountVatTreatment | 'none'
+  onValueChange: (value: AccountVatTreatment | 'none') => void
+  accountClass: number | null
+}
+
+export function AccountVatTreatmentSelect({
+  value,
+  onValueChange,
+  accountClass,
+}: AccountVatTreatmentSelectProps) {
+  const t = useTranslations('chart_of_accounts')
+  const isRelevant = accountClass === 3 ||
+    (accountClass !== null && accountClass >= 4 && accountClass <= 6)
+  const treatments = accountClass === null ? [] : vatTreatmentsForAccountClass(accountClass)
+
+  return (
+    <div className="space-y-2">
+      <Label>{t('vat_treatment_label')}</Label>
+      <Select
+        value={value}
+        onValueChange={(next) => onValueChange(next as AccountVatTreatment | 'none')}
+        disabled={!isRelevant}
+      >
+        <SelectTrigger aria-label={t('vat_treatment_label')}>
+          <SelectValue />
+        </SelectTrigger>
+        <SelectContent>
+          <SelectItem value="none">{t('vat_treatment_none')}</SelectItem>
+          {treatments.map((treatment) => (
+            <SelectItem key={treatment} value={treatment}>
+              {t(`vat_treatment_${treatment}`)}
+            </SelectItem>
+          ))}
+        </SelectContent>
+      </Select>
+      <p className="text-xs text-muted-foreground">
+        {isRelevant ? t('vat_treatment_help') : t('vat_treatment_not_applicable')}
+      </p>
+    </div>
+  )
+}
@@ -19,6 +19,11 @@ import { isStandardBASAccount } from '@/lib/bookkeeping/bas-reference'
 import { classifyAccount } from '@/lib/bookkeeping/account-classifier'
 import type { BASAccount } from '@/types'
 import { getErrorMessage as getUserErrorMessage } from '@/lib/errors/get-error-message'
+import { AccountVatTreatmentSelect } from './AccountVatTreatmentSelect'
+import {
+  defaultRateForVatTreatment,
+  type AccountVatTreatment,
+} from '@/lib/vat/account-vat-treatment'

 /**
 * The create path hands back the full row the API inserted. The reactivate
@@ -49,6 +54,7 @@ export function AddAccountDialog({
  // "Standard moms": the moms-sats a booking line defaults to when this konto is
  // picked. 'none' = no default. SelectItem values are stringified decimals.
  const [defaultVatRate, setDefaultVatRate] = useState('none')
+  const [defaultVatTreatment, setDefaultVatTreatment] = useState<AccountVatTreatment | 'none'>('none')
  const [sruCode, setSruCode] = useState('')
  const [normalBalance, setNormalBalance] = useState<'debit' | 'credit'>('debit')
  const [isSaving, setIsSaving] = useState(false)
@@ -102,6 +108,7 @@ export function AddAccountDialog({
          normal_balance: normalBalance,
          description: description || null,
          default_vat_rate: defaultVatRate === 'none' ? null : parseFloat(defaultVatRate),
+          default_vat_treatment: defaultVatTreatment === 'none' ? null : defaultVatTreatment,
          sru_code: sruCode || null,
        }),
      })
@@ -127,6 +134,7 @@ export function AddAccountDialog({
      setAccountName('')
      setDescription('')
      setDefaultVatRate('none')
+      setDefaultVatTreatment('none')
      setSruCode('')
      onCreated(createdAccount)
      onOpenChange(false)
@@ -162,6 +170,7 @@ export function AddAccountDialog({
      setAccountName('')
      setDescription('')
      setDefaultVatRate('none')
+      setDefaultVatTreatment('none')
      setSruCode('')
      onCreated({ account_number: accountNumber })
      onOpenChange(false)
@@ -260,6 +269,18 @@ export function AddAccountDialog({
            />
          </div>

+          <AccountVatTreatmentSelect
+            value={defaultVatTreatment}
+            accountClass={derived ? Number(accountNumber.charAt(0)) : null}
+            onValueChange={(treatment) => {
+              setDefaultVatTreatment(treatment)
+              if (treatment !== 'none') {
+                const rate = defaultRateForVatTreatment(treatment, Number(accountNumber.charAt(0)))
+                setDefaultVatRate(rate === null ? 'none' : String(rate))
+              }
+            }}
+          />
+
          <div className="grid grid-cols-2 gap-4">
            <div className="space-y-2">
              <Label>Standard moms <span className="text-muted-foreground">(valfritt)</span></Label>
@@ -275,12 +296,6 @@ export function AddAccountDialog({
                  <SelectItem value="0.06">6 %</SelectItem>
                </SelectContent>
              </Select>
-              {accountNumber.length === 4 && accountNumber.startsWith('3') && (
-                <p className="text-xs text-muted-foreground">
-                  På intäktskonton avgör satsen också om kontot räknas som
-                  momspliktig försäljning i ruta 05 i momsdeklarationen.
-                </p>
-              )}
            </div>
            <div className="space-y-2">
              <Label>SRU-kod <span className="text-muted-foreground">(valfritt)</span></Label>
@@ -32,6 +32,11 @@ import {
  type DimensionRuleType,
 } from '@/components/dimensions/types'
 import type { BASAccount } from '@/types'
+import { AccountVatTreatmentSelect } from './AccountVatTreatmentSelect'
+import {
+  defaultRateForVatTreatment,
+  type AccountVatTreatment,
+} from '@/lib/vat/account-vat-treatment'

 interface EditAccountDialogProps {
  open: boolean
@@ -65,6 +70,9 @@ export function EditAccountDialog({ open, onOpenChange, account, onSaved }: Edit
  const [defaultVatRate, setDefaultVatRate] = useState(
    account.default_vat_rate != null ? String(account.default_vat_rate) : 'none',
  )
+  const [defaultVatTreatment, setDefaultVatTreatment] = useState<AccountVatTreatment | 'none'>(
+    account.default_vat_treatment ?? 'none',
+  )
  const [sruCode, setSruCode] = useState(account.sru_code || '')
  const [isActive, setIsActive] = useState(account.is_active)
  const [isSaving, setIsSaving] = useState(false)
@@ -256,6 +264,7 @@ export function EditAccountDialog({ open, onOpenChange, account, onSaved }: Edit
          account_name: accountName,
          description: description || null,
          default_vat_rate: defaultVatRate === 'none' ? null : parseFloat(defaultVatRate),
+          default_vat_treatment: defaultVatTreatment === 'none' ? null : defaultVatTreatment,
          sru_code: sruCode || null,
          is_active: isActive,
        }),
@@ -313,6 +322,18 @@ export function EditAccountDialog({ open, onOpenChange, account, onSaved }: Edit
            />
          </div>

+          <AccountVatTreatmentSelect
+            value={defaultVatTreatment}
+            accountClass={account.account_class}
+            onValueChange={(treatment) => {
+              setDefaultVatTreatment(treatment)
+              if (treatment !== 'none') {
+                const rate = defaultRateForVatTreatment(treatment, account.account_class)
+                setDefaultVatRate(rate === null ? 'none' : String(rate))
+              }
+            }}
+          />
+
          <div className="grid grid-cols-1 sm:grid-cols-2 gap-4">
            <div className="space-y-2">
              <Label>Standard moms</Label>
@@ -328,12 +349,6 @@ export function EditAccountDialog({ open, onOpenChange, account, onSaved }: Edit
                  <SelectItem value="0.06">6 %</SelectItem>
                </SelectContent>
              </Select>
-              {account.account_class === 3 && (
-                <p className="text-xs text-muted-foreground">
-                  På intäktskonton avgör satsen också om kontot räknas som
-                  momspliktig försäljning i ruta 05 i momsdeklarationen.
-                </p>
-              )}
            </div>
            <div className="space-y-2">
              <Label>SRU-kod</Label>
@@ -1,6 +1,7 @@
 'use client'

 import { useState, useMemo } from 'react'
+import { useTranslations } from 'next-intl'
 import { Card, CardContent, CardDescription, CardHeader, CardTitle } from '@/components/ui/card'
 import { Button } from '@/components/ui/button'
 import { Input } from '@/components/ui/input'
@@ -31,16 +32,26 @@ import {
 import type { AccountMapping } from '@/lib/import/types'
 import type { BASAccount } from '@/types'
 import { getAccountClassName } from '@/lib/bookkeeping/account-descriptions'
+import {
+  defaultRateForVatTreatment,
+  vatTreatmentsForAccountClass,
+  type AccountVatTreatment,
+} from '@/lib/vat/account-vat-treatment'

 interface AccountMappingStepProps {
  mappings: AccountMapping[]
  basAccounts: BASAccount[]
  onMappingChange: (sourceAccount: string, targetAccount: string, targetName: string) => void
+  onVatTreatmentChange?: (
+    sourceAccount: string,
+    treatment: AccountVatTreatment | null,
+    rate: number | null,
+  ) => void
  onContinue: () => void
  onBack: () => void
 }

-type FilterType = 'all' | 'unmapped' | 'low_confidence' | 'manual'
+type FilterType = 'all' | 'unmapped' | 'vat_review' | 'low_confidence' | 'manual'

 const PAGE_SIZE = 50

@@ -48,14 +59,17 @@ export default function AccountMappingStep({
  mappings,
  basAccounts,
  onMappingChange,
+  onVatTreatmentChange,
  onContinue,
  onBack,
 }: AccountMappingStepProps) {
+  const t = useTranslations('chart_of_accounts')
  const [searchTerm, setSearchTerm] = useState('')
  // Default to showing unmapped accounts first (most actionable)
  const [filter, setFilter] = useState<FilterType>(() => {
    const hasUnmapped = mappings.some((m) => !m.targetAccount)
-    return hasUnmapped ? 'unmapped' : 'all'
+    const hasVatReview = mappings.some((m) => m.requiresVatTreatmentReview && !m.vatTreatmentReviewed)
+    return hasUnmapped ? 'unmapped' : hasVatReview ? 'vat_review' : 'all'
  })
  const [currentPage, setCurrentPage] = useState(1)

@@ -71,6 +85,9 @@ export default function AccountMappingStep({
      case 'low_confidence':
        result = result.filter((m) => m.targetAccount && m.confidence < 0.7)
        break
+      case 'vat_review':
+        result = result.filter((m) => m.requiresVatTreatmentReview && !m.vatTreatmentReviewed)
+        break
      case 'manual':
        result = result.filter((m) => m.isOverride)
        break
@@ -114,10 +131,11 @@ export default function AccountMappingStep({
    const unmapped = mappings.filter((m) => !m.targetAccount).length
    const lowConfidence = mappings.filter((m) => m.targetAccount && m.confidence < 0.7).length
    const manual = mappings.filter((m) => m.isOverride).length
-    return { unmapped, lowConfidence, manual }
+    const vatReview = mappings.filter((m) => m.requiresVatTreatmentReview && !m.vatTreatmentReviewed).length
+    return { unmapped, lowConfidence, manual, vatReview }
  }, [mappings])

-  const canContinue = stats.unmapped === 0
+  const canContinue = stats.unmapped === 0 && stats.vatReview === 0

  // Group BAS accounts by class for the dropdown
  const accountsByClass = useMemo(() => {
@@ -145,6 +163,14 @@ export default function AccountMappingStep({
        <CardContent className="space-y-4">
          {/* Stats */}
          <div className="flex gap-4 flex-wrap">
+            <Badge
+              variant={filter === 'vat_review' ? 'default' : stats.vatReview > 0 ? 'secondary' : 'outline'}
+              className="cursor-pointer"
+              onClick={() => handleFilterChange('vat_review')}
+            >
+              <AlertCircle className="h-3 w-3 mr-1" />
+              {t('vat_review_filter', { count: stats.vatReview })}
+            </Badge>
            <Badge
              variant={filter === 'unmapped' ? 'destructive' : stats.unmapped > 0 ? 'destructive' : 'secondary'}
              className="cursor-pointer"
@@ -197,6 +223,7 @@ export default function AccountMappingStep({
              <SelectContent>
                <SelectItem value="all">Visa alla</SelectItem>
                <SelectItem value="unmapped">Ej mappade</SelectItem>
+                <SelectItem value="vat_review">{t('vat_review_filter', { count: stats.vatReview })}</SelectItem>
                <SelectItem value="low_confidence">Osäkra</SelectItem>
                <SelectItem value="manual">Manuellt satta</SelectItem>
              </SelectContent>
@@ -211,6 +238,7 @@ export default function AccountMappingStep({
                  <TableHead className="w-36">Källkonto</TableHead>
                  <TableHead>Källnamn</TableHead>
                  <TableHead className="w-12"></TableHead>
+                  <TableHead className="min-w-72">{t('vat_treatment_column')}</TableHead>
                  <TableHead className="w-64">Målkonto</TableHead>
                  <TableHead className="w-24">Konfidens</TableHead>
                </TableRow>
@@ -226,6 +254,78 @@ export default function AccountMappingStep({
                    <TableCell>
                      <ArrowRight className="h-4 w-4 text-muted-foreground" />
                    </TableCell>
+                    <TableCell>
+                      {onVatTreatmentChange &&
+                      mapping.sourceAccount === mapping.targetAccount &&
+                      ['3', '4', '5', '6'].includes(mapping.sourceAccount.charAt(0)) ? (
+                        <div className="flex min-w-72 gap-2">
+                          <Select
+                            value={mapping.defaultVatTreatment ?? 'none'}
+                            onValueChange={(value) => {
+                              const treatment = value === 'none'
+                                ? null
+                                : value as AccountVatTreatment
+                              const accountClass = Number(mapping.sourceAccount.charAt(0))
+                              const rate = treatment
+                                ? defaultRateForVatTreatment(treatment, accountClass)
+                                : null
+                              onVatTreatmentChange(mapping.sourceAccount, treatment, rate)
+                            }}
+                          >
+                            <SelectTrigger className={mapping.requiresVatTreatmentReview ? 'border-warning/60' : ''}>
+                              <SelectValue />
+                            </SelectTrigger>
+                            <SelectContent>
+                              <SelectItem value="none">{t('vat_treatment_none')}</SelectItem>
+                              {vatTreatmentsForAccountClass(
+                                Number(mapping.sourceAccount.charAt(0)),
+                              ).map((treatment) => (
+                                <SelectItem key={treatment} value={treatment}>
+                                  {t(`vat_treatment_${treatment}`)}
+                                </SelectItem>
+                              ))}
+                            </SelectContent>
+                          </Select>
+                          <Select
+                            value={mapping.defaultVatRate === null || mapping.defaultVatRate === undefined
+                              ? 'none'
+                              : String(mapping.defaultVatRate)}
+                            onValueChange={(value) => onVatTreatmentChange(
+                              mapping.sourceAccount,
+                              mapping.defaultVatTreatment ?? null,
+                              value === 'none' ? null : Number(value),
+                            )}
+                          >
+                            <SelectTrigger className="w-24" aria-label={t('vat_rate_label')}>
+                              <SelectValue />
+                            </SelectTrigger>
+                            <SelectContent>
+                              <SelectItem value="none">{t('vat_rate_none')}</SelectItem>
+                              <SelectItem value="0">0 %</SelectItem>
+                              <SelectItem value="0.25">25 %</SelectItem>
+                              <SelectItem value="0.12">12 %</SelectItem>
+                              <SelectItem value="0.06">6 %</SelectItem>
+                            </SelectContent>
+                          </Select>
+                          {mapping.requiresVatTreatmentReview && !mapping.vatTreatmentReviewed && (
+                            <Button
+                              type="button"
+                              variant="outline"
+                              size="sm"
+                              onClick={() => onVatTreatmentChange(
+                                mapping.sourceAccount,
+                                mapping.defaultVatTreatment ?? null,
+                                mapping.defaultVatRate ?? null,
+                              )}
+                            >
+                              {t('vat_treatment_confirm')}
+                            </Button>
+                          )}
+                        </div>
+                      ) : (
+                        <span className="text-muted-foreground">-</span>
+                      )}
+                    </TableCell>
                    <TableCell>
                      <Select
                        value={mapping.targetAccount || 'none'}
@@ -275,7 +375,7 @@ export default function AccountMappingStep({
                ))}
                {paginatedMappings.length === 0 && (
                  <TableRow>
-                    <TableCell colSpan={5} className="text-center text-muted-foreground py-8">
+                    <TableCell colSpan={6} className="text-center text-muted-foreground py-8">
                      Inga konton matchar filtret
                    </TableCell>
                  </TableRow>
@@ -35,6 +35,7 @@ interface ImportResultStepProps {
   *  bridge. Absent (failure, oversized file, parse miss) = plain header. */
  preview?: ImportPreview | null
  theaterModel?: TheaterModel | null
+  unresolvedVatAccountCount?: number
 }

 export default function ImportResultStep({
@@ -43,6 +44,7 @@ export default function ImportResultStep({
  onUndo,
  preview = null,
  theaterModel = null,
+  unresolvedVatAccountCount = 0,
 }: ImportResultStepProps) {
  const t = useTranslations('import')
  const { dialogProps, confirm } = useDestructiveConfirm()
@@ -193,6 +195,23 @@ export default function ImportResultStep({
        </Card>
      )}

+      {result.success && unresolvedVatAccountCount > 0 && (
+        <Card className="border-warning/40">
+          <CardHeader>
+            <CardTitle className="flex items-center gap-2 text-base">
+              <AlertCircle className="h-5 w-5 text-warning" />
+              {t('vat_review_title', { count: unresolvedVatAccountCount })}
+            </CardTitle>
+            <CardDescription>{t('vat_review_description')}</CardDescription>
+          </CardHeader>
+          <CardContent>
+            <Button asChild variant="outline">
+              <Link href="/chart-of-accounts">{t('vat_review_action')}</Link>
+            </Button>
+          </CardContent>
+        </Card>
+      )}
+
      {/* Dimensions detected (lossless SIE round-trip, dimensions plan PR5) */}
      {result.success && result.dimensionsImported && (
        <Card>
@@ -1996,6 +1996,23 @@ describe('CreateAccountSchema', () => {
    })
    expect(result.success).toBe(false)
  })
+
+  it('rejects a VAT treatment that does not apply to the account class', () => {
+    expect(CreateAccountSchema.safeParse({
+      account_number: '5010',
+      account_name: 'Consulting costs',
+      account_type: 'expense',
+      normal_balance: 'debit',
+      default_vat_treatment: 'standard_25',
+    }).success).toBe(false)
+    expect(CreateAccountSchema.safeParse({
+      account_number: '5010',
+      account_name: 'EU services',
+      account_type: 'expense',
+      normal_balance: 'debit',
+      default_vat_treatment: 'reverse_charge_eu_services',
+    }).success).toBe(true)
+  })
 })

 // ============================================================
@@ -2305,6 +2322,14 @@ describe('UpdateAccountSchema', () => {
      default_vat_rate: 0.5,
    }).success).toBe(false)
  })
+
+  it('accepts supported account VAT treatments and rejects unknown values', () => {
+    expect(UpdateAccountSchema.safeParse({
+      default_vat_treatment: 'reverse_charge_eu_goods',
+    }).success).toBe(true)
+    expect(UpdateAccountSchema.safeParse({ default_vat_treatment: null }).success).toBe(true)
+    expect(UpdateAccountSchema.safeParse({ default_vat_treatment: 'eu_purchase' }).success).toBe(false)
+  })
 })

 // ============================================================
@@ -16,6 +16,7 @@ import { INVOICE_POSTING_ACCOUNT_REGEX } from '@/lib/invoices/posting-account'
 import { PERSONAL_NUMBER_INPUT_RE } from '@/lib/customers/mask-personal-number'
 import type { AuditAction } from '@/types'
 import type { BankFileFormatId } from '@/lib/import/bank-file/types'
+import { isVatTreatmentValidForAccountClass } from '@/lib/vat/account-vat-treatment'

 // ============================================================
 // Shared primitives
@@ -2110,6 +2111,15 @@ const defaultVatRate = z
  .nullable()
  .optional()

+export const AccountVatTreatmentSchema = z.enum([
+  'standard_25', 'reduced_12', 'reduced_6', 'exempt',
+  'reverse_charge_domestic', 'reverse_charge_eu_goods',
+  'reverse_charge_eu_services', 'export_goods', 'export_services',
+  'vmb', 'rental_voluntary',
+])
+
+const defaultVatTreatment = AccountVatTreatmentSchema.nullable().optional()
+
 export const CreateAccountSchema = z.object({
  account_number: accountNumber,
  account_name: z.string().min(1, 'Account name is required'),
@@ -2119,7 +2129,22 @@ export const CreateAccountSchema = z.object({
  description: z.string().nullable().optional(),
  default_vat_code: z.string().nullable().optional(),
  default_vat_rate: defaultVatRate,
+  default_vat_treatment: defaultVatTreatment,
  sru_code: z.string().nullable().optional(),
+}).superRefine((value, ctx) => {
+  if (
+    value.default_vat_treatment &&
+    !isVatTreatmentValidForAccountClass(
+      value.default_vat_treatment,
+      Number(value.account_number.charAt(0)),
+    )
+  ) {
+    ctx.addIssue({
+      code: 'custom',
+      path: ['default_vat_treatment'],
+      message: 'VAT treatment is not valid for the account class',
+    })
+  }
 })

 export const UpdateAccountSchema = z.object({
@@ -2128,6 +2153,7 @@ export const UpdateAccountSchema = z.object({
  description: z.string().nullable().optional(),
  default_vat_code: z.string().nullable().optional(),
  default_vat_rate: defaultVatRate,
+  default_vat_treatment: defaultVatTreatment,
  sru_code: z.string().nullable().optional(),
 })

@@ -102,6 +102,25 @@ function run(
 // --- Tests ---

 describe('syncMappedAccounts: create pass', () => {
+  it('persists a reviewed VAT treatment on a created identity account', async () => {
+    const { supabase, inserts } = buildCapturingSupabase()
+    const result = await run(supabase, [
+      mapping({
+        sourceAccount: '4056',
+        targetAccount: '4056',
+        sourceName: 'Inköp varor 25% EU',
+        defaultVatTreatment: 'reverse_charge_eu_goods',
+        defaultVatRate: 0.25,
+        vatTreatmentReviewed: true,
+      }),
+    ])
+    expect(result.error).toBeNull()
+    expect(inserts[0]).toMatchObject({
+      default_vat_treatment: 'reverse_charge_eu_goods',
+      default_vat_rate: 0.25,
+    })
+  })
+
  it('creates a missing BAS account with the BAS default name when the file has no custom name', async () => {
    const { supabase, inserts } = buildCapturingSupabase()

@@ -0,0 +1,94 @@
+import { describe, expect, it } from 'vitest'
+import {
+  applyVatTreatmentReview,
+  enrichAccountMappingsWithVat,
+} from '../account-vat-treatment'
+import type { AccountMapping } from '../types'
+
+function mapping(account: string, name: string): AccountMapping {
+  return {
+    sourceAccount: account,
+    sourceName: name,
+    targetAccount: account,
+    targetName: name,
+    confidence: 1,
+    matchType: 'exact',
+    isOverride: false,
+  }
+}
+
+describe('enrichAccountMappingsWithVat', () => {
+  it('marks label suggestions for user review', () => {
+    const [result] = enrichAccountMappingsWithVat(
+      [mapping('4056', 'Inköp varor 25% EU')],
+      [],
+    )
+    expect(result).toMatchObject({
+      defaultVatTreatment: 'reverse_charge_eu_goods',
+      defaultVatRate: 0.25,
+      vatTreatmentSuggested: true,
+      vatTreatmentReviewed: false,
+      requiresVatTreatmentReview: true,
+    })
+  })
+
+  it('requires review for suggested class 5 and 6 purchase treatments', () => {
+    const results = enrichAccountMappingsWithVat(
+      [
+        mapping('5010', 'Inköp tjänst EU'),
+        mapping('6010', 'Inköp tjänst utanför EU'),
+      ],
+      [],
+    )
+    expect(results).toEqual([
+      expect.objectContaining({
+        defaultVatTreatment: 'reverse_charge_eu_services',
+        requiresVatTreatmentReview: true,
+        vatTreatmentReviewed: false,
+      }),
+      expect.objectContaining({
+        defaultVatTreatment: 'export_services',
+        requiresVatTreatmentReview: true,
+        vatTreatmentReviewed: false,
+      }),
+    ])
+  })
+
+  it('keeps an existing account treatment without asking again', () => {
+    const [result] = enrichAccountMappingsWithVat(
+      [mapping('3041', 'Försäljning tjänst 25% sv')],
+      [{
+        account_number: '3041',
+        default_vat_treatment: 'standard_25',
+        default_vat_rate: 0.25,
+      } as never],
+    )
+    expect(result).toMatchObject({
+      defaultVatTreatment: 'standard_25',
+      vatTreatmentSuggested: false,
+      vatTreatmentReviewed: true,
+      requiresVatTreatmentReview: false,
+    })
+  })
+})
+
+describe('applyVatTreatmentReview', () => {
+  it('marks only the selected row reviewed, including class 5 and 6 accounts', () => {
+    const mappings = [
+      mapping('5010', 'Inköp tjänst EU'),
+      mapping('3041', 'Försäljning tjänst 25% sv'),
+    ]
+    const result = applyVatTreatmentReview(
+      mappings,
+      '5010',
+      'reverse_charge_eu_services',
+      0.25,
+    )
+    expect(result[0]).toMatchObject({
+      defaultVatTreatment: 'reverse_charge_eu_services',
+      defaultVatRate: 0.25,
+      vatTreatmentReviewed: true,
+    })
+    expect(result[1].vatTreatmentReviewed).toBeUndefined()
+  })
+})
@@ -14,6 +14,7 @@ import { classifyAccount } from '@/lib/bookkeeping/account-classifier'
 import { computeSRUCode } from '@/lib/bookkeeping/bas-data/sru-mapping'
 import { fetchAllRows } from '@/lib/supabase/fetch-all'
 import type { AccountMapping } from './types'
+import { isAccountVatTreatment, type AccountVatTreatment } from '@/lib/vat/account-vat-treatment'

 export interface AccountSyncResult {
  /** Accounts inserted into chart_of_accounts */
@@ -43,6 +44,7 @@ function buildInsertRow(
  basRef: BASReferenceAccount | undefined,
  companyId: string,
  userId: string,
+  vatDefaults?: { treatment: AccountVatTreatment | null; rate: number | null },
 ) {
  const sortOrder = /^\d+$/.test(accountNumber) ? parseInt(accountNumber, 10) : null

@@ -63,6 +65,8 @@ function buildInsertRow(
      is_system_account: false,
      description: basRef.description,
      sort_order: sortOrder,
+      default_vat_treatment: vatDefaults?.treatment ?? null,
+      default_vat_rate: vatDefaults?.rate ?? null,
    }
  }

@@ -84,6 +88,8 @@ function buildInsertRow(
    is_system_account: false,
    description: accountName,
    sort_order: sortOrder,
+    default_vat_treatment: vatDefaults?.treatment ?? null,
+    default_vat_rate: vatDefaults?.rate ?? null,
  }
 }

@@ -143,6 +149,27 @@ export async function syncMappedAccounts(
    if (m.targetAccount && fallback) fallbackNames.set(m.targetAccount, fallback)
  }

+  const vatDefaults = new Map<string, { treatment: AccountVatTreatment | null; rate: number | null }>()
+  for (const mapping of mappings) {
+    if (
+      !mapping.vatTreatmentReviewed ||
+      !mapping.targetAccount ||
+      mapping.sourceAccount !== mapping.targetAccount
+    ) continue
+    if (
+      mapping.defaultVatTreatment !== null &&
+      mapping.defaultVatTreatment !== undefined &&
+      !isAccountVatTreatment(mapping.defaultVatTreatment)
+    ) {
+      result.error = `Invalid VAT treatment for account ${mapping.sourceAccount}`
+      return result
+    }
+    vatDefaults.set(mapping.targetAccount, {
+      treatment: mapping.defaultVatTreatment ?? null,
+      rate: mapping.defaultVatRate ?? null,
+    })
+  }
+
  // Fetch the company's chart once (paged) and filter in JS: avoids a huge
  // .in() URL for full-chart imports and the silent 1000-row PostgREST cap.
  let existingByNumber: Map<string, string>
@@ -181,7 +208,7 @@ export async function syncMappedAccounts(
        basRef?.account_name ??
        fallbackNames.get(num) ??
        `Konto ${num}`
-      return buildInsertRow(num, name, basRef, companyId, userId)
+      return buildInsertRow(num, name, basRef, companyId, userId, vatDefaults.get(num))
    })

    const { error: insertError } = await supabase.from('chart_of_accounts').insert(inserts)
@@ -195,6 +222,23 @@ export async function syncMappedAccounts(
    result.created = missing.length
  }

+  const existingVatUpdates = [...vatDefaults]
+    .filter(([account]) => existingByNumber.has(account))
+  for (const [account, defaults] of existingVatUpdates) {
+    const { error: vatUpdateError } = await supabase
+      .from('chart_of_accounts')
+      .update({
+        default_vat_treatment: defaults.treatment,
+        default_vat_rate: defaults.rate,
+      })
+      .eq('company_id', companyId)
+      .eq('account_number', account)
+    if (vatUpdateError) {
+      result.error = vatUpdateError.message
+      return result
+    }
+  }
+
  // Rename pass: carry the file's names into existing accounts. The diff set
  // is small (only names that actually changed), so the UPDATEs run
  // concurrently in bounded batches: a full-chart re-sync must not serialize
@@ -0,0 +1,67 @@
+import type { BASAccount } from '@/types'
+import {
+  suggestVatTreatment,
+  type AccountVatTreatment,
+} from '@/lib/vat/account-vat-treatment'
+import type { AccountMapping } from './types'
+
+/**
+ * Add reviewable VAT suggestions to identity mappings. SIE itself has no VAT
+ * treatment record, so suggestions come only from the account label and are
+ * never considered reviewed until the user continues from the mapping step.
+ */
+export function enrichAccountMappingsWithVat(
+  mappings: AccountMapping[],
+  existingAccounts: BASAccount[],
+): AccountMapping[] {
+  const existingByNumber = new Map(
+    existingAccounts.map((account) => [account.account_number, account]),
+  )
+
+  return mappings.map((mapping) => {
+    if (!mapping.targetAccount || mapping.sourceAccount !== mapping.targetAccount) return mapping
+    const accountClass = Number(mapping.sourceAccount.charAt(0))
+    if (accountClass < 3 || accountClass > 6) return mapping
+
+    const existing = existingByNumber.get(mapping.targetAccount)
+    if (existing?.default_vat_treatment) {
+      return {
+        ...mapping,
+        defaultVatTreatment: existing.default_vat_treatment,
+        defaultVatRate: existing.default_vat_rate,
+        vatTreatmentReviewed: true,
+        vatTreatmentSuggested: false,
+        requiresVatTreatmentReview: false,
+      }
+    }
+
+    const suggestion = suggestVatTreatment(mapping.sourceAccount, mapping.sourceName)
+    return {
+      ...mapping,
+      defaultVatTreatment: suggestion?.treatment ?? null,
+      defaultVatRate: suggestion?.rate ?? existing?.default_vat_rate ?? null,
+      vatTreatmentSuggested: Boolean(suggestion),
+      vatTreatmentReviewed: false,
+      requiresVatTreatmentReview: accountClass >= 3 && accountClass <= 6,
+    }
+  })
+}
+
+export function applyVatTreatmentReview(
+  mappings: AccountMapping[],
+  sourceAccount: string,
+  treatment: AccountVatTreatment | null,
+  rate: number | null,
+): AccountMapping[] {
+  return mappings.map((mapping) =>
+    mapping.sourceAccount === sourceAccount
+      ? {
+          ...mapping,
+          defaultVatTreatment: treatment,
+          defaultVatRate: rate,
+          vatTreatmentSuggested: false,
+          vatTreatmentReviewed: true,
+        }
+      : mapping
+  )
+}
@@ -185,6 +185,11 @@ export interface AccountMapping {
  confidence: number               // 0-1
  matchType: AccountMatchType
  isOverride: boolean              // User manually set this
+  defaultVatTreatment?: import('@/lib/vat/account-vat-treatment').AccountVatTreatment | null
+  defaultVatRate?: number | null
+  vatTreatmentSuggested?: boolean
+  vatTreatmentReviewed?: boolean
+  requiresVatTreatmentReview?: boolean
 }

 /**
@@ -21,6 +21,11 @@ vi.mock('@/lib/bookkeeping/entry-lines', () => ({
  fetchLinesByEntryIds: (...args: unknown[]) => fetchLinesByEntryIdsMock(...args),
 }))

+const fetchDynamicVatAccountsMock = vi.fn()
+vi.mock('../vat-revenue-accounts', () => ({
+  fetchDynamicVatAccounts: (...args: unknown[]) => fetchDynamicVatAccountsMock(...args),
+}))
+
 import { findRcBasisGaps } from '../rc-basis-gaps'

 const supabase = {} as SupabaseClient
@@ -47,6 +52,10 @@ describe('findRcBasisGaps', () => {
    resolvePeriodDatesMock.mockResolvedValue({ start: '2025-07-17', end: '2026-12-31' })
    fetchEntryLinesMock.mockResolvedValue([])
    fetchLinesByEntryIdsMock.mockResolvedValue([])
+    fetchDynamicVatAccountsMock.mockResolvedValue({
+      explicitAccounts: new Set(),
+      rcBasisRateByAccount: new Map(),
+    })
  })

  it('resolves the period via resolvePeriodDates with the fiscal period id', async () => {
@@ -124,4 +133,32 @@ describe('findRcBasisGaps', () => {
    expect(gaps).toHaveLength(1)
    expect(gaps[0].expectedBasisAmount).toBe(10000)
  })
+
+  it('accepts a custom EU purchase basis account at the matching rate', async () => {
+    fetchDynamicVatAccountsMock.mockResolvedValue({
+      explicitAccounts: new Set(['4056']),
+      rcBasisRateByAccount: new Map([['4056', 0.25]]),
+    })
+    fetchEntryLinesMock.mockResolvedValue([rcLine('entry-1', 8, 250)])
+    fetchLinesByEntryIdsMock.mockResolvedValue([{
+      id: 'l-1', journal_entry_id: 'entry-1', account_number: '4056',
+      debit_amount: 1000, credit_amount: 0,
+    }])
+    await expect(findRcBasisGaps(supabase, 'company-1', 'monthly', 2026, 5))
+      .resolves.toEqual([])
+  })
+
+  it('does not let a 25 percent basis cover 12 percent output VAT', async () => {
+    fetchEntryLinesMock.mockResolvedValue([{
+      ...rcLine('entry-1', 8, 120),
+      account_number: '2624',
+    }])
+    fetchLinesByEntryIdsMock.mockResolvedValue([{
+      id: 'l-1', journal_entry_id: 'entry-1', account_number: '4535',
+      debit_amount: 1000, credit_amount: 0,
+    }])
+    const gaps = await findRcBasisGaps(supabase, 'company-1', 'monthly', 2026, 5)
+    expect(gaps).toHaveLength(1)
+    expect(gaps[0].rate).toBe(0.12)
+  })
 })
@@ -16,7 +16,9 @@ let results: Array<{ data?: unknown; error?: unknown }>
 let chartAccounts: Array<{
  account_number: string
  account_name?: string
+  account_class?: number
  default_vat_rate: number | null
+  default_vat_treatment?: string | null
 }>

 function makeBuilder() {
@@ -37,12 +39,17 @@ function makeBuilder() {
 */
 function makeChartBuilder() {
  const b: Record<string, unknown> = {}
-  for (const m of ['select', 'eq', 'in', 'not', 'order', 'range']) {
+  for (const m of ['select', 'eq', 'gte', 'lte', 'in', 'not', 'order', 'range']) {
    b[m] = vi.fn().mockReturnValue(b)
  }
  b.then = (resolve: (v: unknown) => void) =>
    resolve({
-      data: chartAccounts.map((account) => ({ account_name: '', ...account })),
+      data: chartAccounts.map((account) => ({
+        account_name: '',
+        account_class: 3,
+        default_vat_treatment: null,
+        ...account,
+      })),
      error: null,
    })
  return b
@@ -117,6 +124,36 @@ beforeEach(() => {
 // Pure function tests: no mocks needed
 // ============================================================

+describe('rutorFromTotals: explicit account VAT treatments', () => {
+  it('puts a custom sales account in ruta 05', () => {
+    const totals = new Map([['3041', { debit: 0, credit: 1000 }]])
+    const rutor = rutorFromTotals(totals, {
+      mappingByAccount: new Map([['3041', { box: 'ruta05', side: 'credit' }]]),
+      explicitAccounts: new Set(['3041']),
+    })
+    expect(rutor.ruta05).toBe(1000)
+  })
+
+  it('puts a custom EU purchase account in ruta 20', () => {
+    const totals = new Map([['4056', { debit: 1000, credit: 0 }]])
+    const rutor = rutorFromTotals(totals, {
+      mappingByAccount: new Map([['4056', { box: 'ruta20', side: 'debit' }]]),
+      explicitAccounts: new Set(['4056']),
+    })
+    expect(rutor.ruta20).toBe(1000)
+  })
+
+  it('keeps a static BAS mapping authoritative over an explicit treatment', () => {
+    const totals = new Map([['3001', { debit: 0, credit: 1000 }]])
+    const rutor = rutorFromTotals(totals, {
+      mappingByAccount: new Map([['3001', { box: 'ruta42', side: 'credit' }]]),
+      explicitAccounts: new Set(['3001']),
+    })
+    expect(rutor.ruta05).toBe(1000)
+    expect(rutor.ruta42).toBe(0)
+  })
+})
+
 describe('rutorFromTotals: ruta 41 (omvänd skattskyldighet, sales side)', () => {
  it('projects 3231/3232/3233 credit balances into ruta 41', () => {
    const totals = new Map([
@@ -6,6 +6,7 @@ import {
 } from '@/lib/bookkeeping/entry-lines'
 import { resolvePeriodDates } from './vat-declaration'
 import { RC_BASIS_ACCOUNTS_BY_RATE } from './vat-filing-gate'
+import { fetchDynamicVatAccounts } from './vat-revenue-accounts'
 import type { VatPeriodType } from '@/types'

 /**
@@ -24,10 +25,10 @@ type RcOutputAccount = typeof RC_OUTPUT_ACCOUNTS[number]
 // domestic goods RC (4415-4417), domestic services RC (4425-4427). Derived
 // from the rate-grouped single source in vat-filing-gate.ts so this scan and
 // the per-rate downgrade evidence can never disagree on the account set.
-const RC_BASIS_ACCOUNTS = new Set<string>([
-  ...RC_BASIS_ACCOUNTS_BY_RATE.r25,
-  ...RC_BASIS_ACCOUNTS_BY_RATE.r12,
-  ...RC_BASIS_ACCOUNTS_BY_RATE.r6,
+const STATIC_RC_BASIS_RATE = new Map<string, number>([
+  ...RC_BASIS_ACCOUNTS_BY_RATE.r25.map((account) => [account, 0.25] as const),
+  ...RC_BASIS_ACCOUNTS_BY_RATE.r12.map((account) => [account, 0.12] as const),
+  ...RC_BASIS_ACCOUNTS_BY_RATE.r6.map((account) => [account, 0.06] as const),
 ])

 const RATE_BY_OUTPUT: Record<RcOutputAccount, number> = {
@@ -119,6 +120,7 @@ export async function findRcBasisGaps(
  const { start, end } = await resolvePeriodDates(
    supabase, companyId, periodType, year, period, options.fiscalPeriodId
  )
+  const dynamicVatAccounts = await fetchDynamicVatAccounts(supabase, companyId)

  // Two-step entry-lines fetch (see lib/bookkeeping/entry-lines.ts).
  const rcLines = (await fetchEntryLines<unknown>({
@@ -146,12 +148,15 @@ export async function findRcBasisGaps(
    'id, journal_entry_id, account_number, debit_amount, credit_amount',
  )

-  const basisByEntry = new Map<string, number>()
+  const basisByEntryAndRate = new Map<string, number>()
  for (const line of siblingLines) {
-    if (RC_BASIS_ACCOUNTS.has(line.account_number)) {
-      const prev = basisByEntry.get(line.journal_entry_id) || 0
-      basisByEntry.set(
-        line.journal_entry_id,
+    const rate = STATIC_RC_BASIS_RATE.get(line.account_number) ??
+      dynamicVatAccounts.rcBasisRateByAccount.get(line.account_number)
+    if (rate) {
+      const key = `${line.journal_entry_id}:${rate}`
+      const prev = basisByEntryAndRate.get(key) || 0
+      basisByEntryAndRate.set(
+        key,
        prev + (Number(line.debit_amount) || 0) - (Number(line.credit_amount) || 0),
      )
    }
@@ -179,7 +184,7 @@ export async function findRcBasisGaps(
    const rate = RATE_BY_OUTPUT[account]
    if (!rate) continue
    const expectedBasis = Math.round((amount / rate) * 100) / 100
-    const actualBasis = basisByEntry.get(row.journal_entry_id) || 0
+    const actualBasis = basisByEntryAndRate.get(`${row.journal_entry_id}:${rate}`) || 0
    if (actualBasis + eps >= expectedBasis) continue

    const entry = pickEntry(row)
@@ -6,7 +6,7 @@ import type {
 } from '@/types'
 import type { VatCheckAccountTotals } from './vat-declaration-checks'
 import { rcBasisTotalsByRate } from './vat-filing-gate'
-import { fetchDynamicRuta05Accounts } from './vat-revenue-accounts'
+import { fetchDynamicVatAccounts, type DynamicVatAccounts } from './vat-revenue-accounts'

 /**
 * Calculate VAT declaration (Momsdeklaration) for a given period.
@@ -414,8 +414,16 @@ export async function fetchVatAccountTotals(
 */
 export function rutorFromTotals(
  totals: Map<string, { debit: number; credit: number }>,
-  dynamicRuta05Accounts: string[] = []
+  dynamicVatAccounts?: Pick<DynamicVatAccounts, 'mappingByAccount' | 'explicitAccounts'> | string[],
 ): VatDeclarationRutor {
+  const dynamic = Array.isArray(dynamicVatAccounts)
+    ? {
+        mappingByAccount: new Map(dynamicVatAccounts.map((account) => [
+          account, { box: 'ruta05' as const, side: 'credit' as const },
+        ])),
+        explicitAccounts: new Set<string>(),
+      }
+    : dynamicVatAccounts
  const rutor: VatDeclarationRutor = {
    ruta05: 0, ruta06: 0, ruta07: 0, ruta08: 0,
    ruta10: 0, ruta11: 0, ruta12: 0,
@@ -436,12 +444,12 @@ export function rutorFromTotals(
    rutor[mapping.box] = round(rutor[mapping.box] + balance)
  }

-  // The company's own momspliktiga intäktskonton. Always credit-side: these are
-  // revenue accounts by construction (account_class 3).
-  for (const account of dynamicRuta05Accounts) {
+  for (const [account, mapping] of dynamic?.mappingByAccount ?? []) {
+    if (ACCOUNT_RUTA[account]) continue
    const t = totals.get(account)
    if (!t) continue
-    rutor.ruta05 = round(rutor.ruta05 + (t.credit - t.debit))
+    const balance = mapping.side === 'credit' ? t.credit - t.debit : t.debit - t.credit
+    rutor[mapping.box] = round(rutor[mapping.box] + balance)
  }

  // FK009: summaMoms = (10 + 11 + 12 + 30 + 31 + 32 + 60 + 61 + 62) - 48
@@ -525,16 +533,16 @@ export async function calculateVatDeclaration(
  // försäljning. Resolved from their "Standard moms" rather than a fixed BAS
  // list, because Accounted seeds no varugrupp accounts: every 3011/3013-style
  // konto is user-added and would otherwise never be fetched at all (#1261).
-  const dynamicRuta05 = await fetchDynamicRuta05Accounts(supabase, companyId)
+  const dynamicVatAccounts = await fetchDynamicVatAccounts(supabase, companyId)

  // Fetch and aggregate posted VAT-account activity for the period. The same
  // RPC round trip carries the per-source_type entry counts for the metadata.
  const { totals, sourceTypeCounts } = await fetchVatAccountTotals(
-    supabase, companyId, start, end, dynamicRuta05.accounts
+    supabase, companyId, start, end, dynamicVatAccounts.accounts
  )

  // Map account balances to momsdeklaration boxes
-  const rutor = rutorFromTotals(totals, dynamicRuta05.accounts)
+  const rutor = rutorFromTotals(totals, dynamicVatAccounts)

  // Compute per-rate base amounts from individual revenue accounts. The
  // company's own accounts carry their rate on the konto itself, so they land
@@ -556,7 +564,7 @@ export async function calculateVatDeclaration(
    const t = totals.get(account)
    if (t) revenueByRate[rate] = round(t.credit - t.debit)
  }
-  for (const [account, rate] of dynamicRuta05.rateByAccount) {
+  for (const [account, rate] of dynamicVatAccounts.rateByAccount) {
    const t = totals.get(account)
    if (!t) continue
    const bucket = RATE_BUCKET[rate as keyof typeof RATE_BUCKET]
@@ -567,7 +575,7 @@ export async function calculateVatDeclaration(
  // gruppkonto) but whose rate only exists as the konto's "Standard moms".
  // Rate-only on purpose: their balance is in ruta 05 either way, so adding
  // them to dynamicRuta05.accounts would double the filed figure.
-  for (const [account, rate] of dynamicRuta05.staticRateByAccount) {
+  for (const [account, rate] of dynamicVatAccounts.staticRateByAccount) {
    const t = totals.get(account)
    if (!t) continue
    const bucket = RATE_BUCKET[rate as keyof typeof RATE_BUCKET]
@@ -597,7 +605,7 @@ export async function calculateVatDeclaration(
    rcInputAccountTotals: rcInputTotals(totals),
    // Per-momssats RC basis balances (44xx/45xx), the downgrade evidence for
    // the per-voucher gap tiering: see VatDeclaration.rcBasisByRate.
-    rcBasisByRate: rcBasisTotalsByRate(totals),
+    rcBasisByRate: rcBasisTotalsByRate(totals, dynamicVatAccounts),
    invoiceCount,
    transactionCount,
    breakdown: {
@@ -3,6 +3,7 @@ import type {
  VatCheckAccountTotals,
 } from './vat-declaration-checks'
 import type { VatDeclarationRutor } from '@/types'
+import { roundOre } from '@/lib/money'

 /**
 * The filing gate for the momsdeklaration: ONE derived value that the
@@ -93,6 +94,12 @@ export const RC_BASIS_ACCOUNTS_BY_RATE = {
  r6: ['4517', '4537', '4533', '4417', '4427'],
 } as const

+const STATIC_RC_BASIS_ACCOUNTS = new Set<string>([
+  ...RC_BASIS_ACCOUNTS_BY_RATE.r25,
+  ...RC_BASIS_ACCOUNTS_BY_RATE.r12,
+  ...RC_BASIS_ACCOUNTS_BY_RATE.r6,
+])
+
 /** Net debit balance of the RC basis accounts, one figure per momssats. */
 export interface RcBasisTotalsByRate {
  r25: number
@@ -106,7 +113,10 @@ export interface RcBasisTotalsByRate {
 * Debit minus credit, like every basis box: a credit-heavy rate (a period
 * dominated by credit notes) legitimately comes out negative.
 */
-export function rcBasisTotalsByRate(totals: VatCheckAccountTotals): RcBasisTotalsByRate {
+export function rcBasisTotalsByRate(
+  totals: VatCheckAccountTotals,
+  dynamic?: { explicitAccounts: Set<string>; rcBasisRateByAccount: Map<string, number> },
+): RcBasisTotalsByRate {
  const sumGroup = (accounts: readonly string[]): number => {
    let sum = 0
    for (const account of accounts) {
@@ -115,11 +125,19 @@ export function rcBasisTotalsByRate(totals: VatCheckAccountTotals): RcBasisTotal
    }
    return Math.round(sum * 100) / 100
  }
-  return {
+  const result = {
    r25: sumGroup(RC_BASIS_ACCOUNTS_BY_RATE.r25),
    r12: sumGroup(RC_BASIS_ACCOUNTS_BY_RATE.r12),
    r6: sumGroup(RC_BASIS_ACCOUNTS_BY_RATE.r6),
  }
+  for (const [account, rate] of dynamic?.rcBasisRateByAccount ?? []) {
+    if (STATIC_RC_BASIS_ACCOUNTS.has(account)) continue
+    const total = totals.get(account)
+    if (!total) continue
+    const key = rate === 0.25 ? 'r25' : rate === 0.12 ? 'r12' : 'r6'
+    result[key] = roundOre(result[key] + total.debit - total.credit)
+  }
+  return result
 }

 /**
@@ -1,224 +1,129 @@
 import type { SupabaseClient } from '@supabase/supabase-js'
 import { fetchAllRows } from '@/lib/supabase/fetch-all'
 import { ACCOUNT_TO_BOX } from '@/lib/vat/moms-box-mapping'
+import {
+  defaultRateForVatTreatment,
+  isAccountVatTreatment,
+  resolveVatTreatmentRuta,
+  type AccountVatRutaMapping,
+} from '@/lib/vat/account-vat-treatment'

-/**
- * Resolve which of a company's OWN revenue accounts belong in ruta 05
- * (momspliktig försäljning som inte ingår i någon annan ruta).
- *
- * ACCOUNT_RUTA is a fixed BAS whitelist and ruta 05 is literally 3001/3002/3003
- * there. That is only correct for a company that never touched its kontoplan:
- * the shipped BAS reference (lib/bookkeeping/bas-data/class-3-revenue.ts) has
- * no varugrupp accounts at all, so every 3011/3013/3041-style konto is added by
- * the user. Their revenue was not merely mapped to the wrong ruta, it was never
- * fetched from the ledger: ACCOUNT_RUTA's keys ARE the account filter passed to
- * get_vat_declaration_totals. Ruta 05 came out short and, because
- * runVatDeclarationChecks compares rutor 05-08 against 10-12, a perfectly
- * correct declaration got a blocking OUTPUT_VAT_WITHOUT_SALES error (#1261).
- *
- * The per-account "Standard moms" (chart_of_accounts.default_vat_rate) is the
- * primary resolver: a class 3 konto the user marked 25/12/6 % is by definition
- * domestic taxable sales, which is exactly what ruta 05 collects. For a
- * missing value, the narrow 30x1/30x2/30x3 convention is accepted only when
- * the account label explicitly confirms the same rate. This recovers imported
- * and older custom accounts without guessing from a number or free text alone.
- */
-
-/**
- * Class 3 accounts that carry a moms-sats but belong in a DIFFERENT ruta, so
- * "has a rate" must not be read as "ruta 05". Per the SKV 4700 mapping in
- * .claude/skills/swedish-vat/references/vat-compliance-reference.md §7:
- *
- *   3211/3212/3220 → ruta 07 (vinstmarginalbeskattning)
- *   3913           → ruta 08 (hyresinkomster, frivillig skattskyldighet)
- *
- * Rutor 07 and 08 are not mappable yet (see the note in
- * vat-declaration-checks.ts). Until they are, these accounts stay out of the
- * declaration entirely: that understates one ruta, whereas sweeping them into
- * ruta 05 would file the amount in the wrong box.
- *
- * 3231/3232/3233 (ruta 41, omvänd skattskyldighet) used to sit here for the
- * same reason but are now statically mapped in ACCOUNT_RUTA/ACCOUNT_TO_BOX,
- * so the ACCOUNT_TO_BOX guard below excludes them from ruta 05.
- */
-export const RUTA_05_EXCLUDED_ACCOUNTS = new Set([
-  '3211', '3212', '3220',
-  '3913',
-])
-
-/** VAT rates that mark a configured konto as momspliktig försäljning. */
 const TAXABLE_RATES = [0.25, 0.12, 0.06]
-
-const DOMESTIC_SALES_RATE_BY_SUFFIX: Record<string, number> = {
-  '1': 0.25,
-  '2': 0.12,
-  '3': 0.06,
-}
-
-/**
- * Labels that contradict "momspliktig försäljning inom Sverige". Any hit vetoes
- * the fallback even when the suffix and a "25/12/6 % moms" label agree: a konto
- * named "momsfri", "omvänd betalningsskyldighet", VMB or export belongs in
- * ruta 07/08/35/36/41, and inferring a sats for it would file the amount in
- * ruta 05, i.e. in the wrong box. Omission is the safe failure here, so a
- * contradictory label falls back to today's behaviour instead of guessing.
- *
- * Only consulted for a MISSING rate. An explicitly configured value stays
- * authoritative and never reaches this check.
- *
- * The word boundaries are load-bearing, not decoration. "0 %" needs a leading
- * \b or it also matches the trailing zero of "10/20/30/100 %", vetoing a
- * perfectly ordinary "Försäljning varor 25 % moms, rabatt 30 %" and recreating
- * the #1261 omission this module exists to remove. "vmb" needs both boundaries
- * because three letters occur inside unrelated words. "export" and "utanför"
- * are matched as bare substrings on purpose, so Swedish compounds
- * ("exportförsäljning") are caught too; both are distinctive enough that a
- * false hit would have to be contrived.
- */
+export const RUTA_05_EXCLUDED_ACCOUNTS = new Set([
+  '3211', '3212', '3220', '3913',
+])
+const RUTA_05_STATIC_RATE_ACCOUNTS = new Set(['3000'])
+const DOMESTIC_SALES_RATE_BY_SUFFIX: Record<string, number> = { '1': 0.25, '2': 0.12, '3': 0.06 }
 const CONTRADICTING_ACCOUNT_NAME =
  /momsfri|momsfritt|utan moms|omvänd|\bvmb\b|vinstmarginal|export|utanför|eu-land|unionsintern|\b0\s*%/i

-/**
- * Resolve a missing rate for a company-specific domestic sales sub-account.
- *
- * Neither signal is sufficient by itself:
- *   - 3011 is not in the BAS 2026 catalog and custom numbers can be repurposed;
- *   - account labels are free text and can be stale or contradictory.
- *
- * Requiring the conventional 30x1/30x2/30x3 suffix and one matching explicit
- * "25/12/6 % moms" label keeps the fallback deterministic. A configured value,
- * including explicit 0 %, is always authoritative and never reaches here.
- *
- * Three ways this deliberately answers null:
- *   - the label states no sats, or states it without the word "moms"
- *     ("Försäljning konsult 25 %" is a margin or a share, not a moms-sats);
- *   - the label states two different sats, so neither can be trusted;
- *   - the label also carries a contradicting term (see above).
- */
-function inferDomesticSalesRate(
-  accountNumber: string,
-  accountName: string | null | undefined,
-): number | null {
+function inferDomesticSalesRate(accountNumber: string, accountName: string): number | null {
  const accountMatch = /^30\d([123])$/.exec(accountNumber)
-  if (!accountMatch) return null
-
-  const name = accountName ?? ''
-  if (CONTRADICTING_ACCOUNT_NAME.test(name)) return null
-
+  if (!accountMatch || CONTRADICTING_ACCOUNT_NAME.test(accountName)) return null
  const expectedRate = DOMESTIC_SALES_RATE_BY_SUFFIX[accountMatch[1]]
  const namedRates = new Set(
-    [...name.matchAll(/\b(25|12|6)\s*%\s*moms\b/gi)].map(
-      (match) => Number(match[1]) / 100,
-    )
+    [...accountName.matchAll(/\b(25|12|6)\s*%\s*moms\b/gi)].map((match) => Number(match[1]) / 100),
  )
-
  return namedRates.size === 1 && namedRates.has(expectedRate) ? expectedRate : null
 }

-/**
- * Ruta 05 accounts that ACCOUNT_TO_BOX already sums, but whose per-rate bucket
- * cannot be inferred from the account number.
- *
- * 3000 "Försäljning inom Sverige" is the BAS gruppkonto for the 30xx range. A
- * BAS-conformant company posts to 3001/3002/3003 and never to 3000, but a
- * company that does post to it has genuine domestic taxable sales, so ruta 05
- * stays the right box and the filed figure is already correct. What is missing
- * is only the rate split: unlike 3001/3002/3003 the number carries no sats, so
- * `breakdown.invoices.base25/12/6` would not add up to ruta 05.
- *
- * These accounts therefore contribute a RATE ONLY. Adding them to `accounts`
- * would double-count them, since ACCOUNT_TO_BOX already puts them in the sum.
- */
-const RUTA_05_STATIC_RATE_ACCOUNTS = new Set(['3000'])
-
-export interface DynamicRuta05Accounts {
-  /** Accounts to add to the ledger fetch and to the ruta 05 sum. */
+export interface DynamicVatAccounts {
  accounts: string[]
-  /** account_number → 0.25 | 0.12 | 0.06, for the per-rate base breakdown. */
+  mappingByAccount: Map<string, AccountVatRutaMapping>
+  explicitAccounts: Set<string>
  rateByAccount: Map<string, number>
-  /**
-   * Rates for accounts ALREADY counted in ruta 05 by the static map. Feeds the
-   * base breakdown only, never the sum. Empty unless the user set a
-   * "Standard moms" on one of RUTA_05_STATIC_RATE_ACCOUNTS.
-   */
  staticRateByAccount: Map<string, number>
+  rcBasisRateByAccount: Map<string, number>
 }

-const EMPTY: DynamicRuta05Accounts = {
-  accounts: [],
-  rateByAccount: new Map(),
-  staticRateByAccount: new Map(),
-}
+const emptyDynamicVatAccounts = (): DynamicVatAccounts => ({
+  accounts: [], mappingByAccount: new Map(), explicitAccounts: new Set(),
+  rateByAccount: new Map(), staticRateByAccount: new Map(),
+  rcBasisRateByAccount: new Map(),
+})

-/**
- * Fetch the company-specific ruta 05 accounts.
- *
- * Excluded:
- *   - every account in ACCOUNT_TO_BOX. This covers all of ACCOUNT_RUTA (the
- *     alignment test in lib/vat/__tests__/moms-box-mapping.test.ts fails if the
- *     mirror ever stops being a superset) and additionally the accounts only
- *     the mirror maps (3106, 3109, 3521, 3522). Filtering on the superset alone
- *     keeps this module off vat-declaration.ts, which imports it.
- *
- *     This exclusion is what makes the BAS backfill safe: it sets 3001 = 25 %,
- *     and without it 3001 would be counted once by ACCOUNT_RUTA and once here,
- *     doubling ruta 05.
- *   - RUTA_05_EXCLUDED_ACCOUNTS above.
- *
- * The company_id filter is explicit rather than left to RLS:
- * calculateVatDeclaration is also reached from /api/v1/* on a service client,
- * which has no RLS.
- */
-export async function fetchDynamicRuta05Accounts(
+/** Explicit treatments extend custom accounts; fixed BAS mappings stay authoritative. */
+export async function fetchDynamicVatAccounts(
  supabase: SupabaseClient,
-  companyId: string
-): Promise<DynamicRuta05Accounts> {
+  companyId: string,
+): Promise<DynamicVatAccounts> {
  const rows = await fetchAllRows<{
    account_number: string
    account_name: string
+    account_class: number
    default_vat_rate: number | string | null
+    default_vat_treatment: string | null
  }>(
-    ({ from, to }) =>
-      supabase
-        .from('chart_of_accounts')
-        .select('account_number, account_name, default_vat_rate')
-        .eq('company_id', companyId)
-        .eq('account_class', 3)
-        // Deactivated accounts only. is_active is nullable (boolean DEFAULT
-        // true, never made NOT NULL) and the accounts API treats only an
-        // explicit false as deactivated, so `eq(true)` would silently drop a
-        // NULL-flagged konto: the same kind of quiet omission this whole fix
-        // exists to remove.
-        .not('is_active', 'is', false)
-        .order('account_number', { ascending: true })
-        .range(from, to)
+    ({ from, to }) => supabase.from('chart_of_accounts')
+      .select('account_number, account_name, account_class, default_vat_rate, default_vat_treatment')
+      .eq('company_id', companyId)
+      .in('account_class', [3, 4, 5, 6])
+      .not('is_active', 'is', false)
+      .order('account_number', { ascending: true })
+      .range(from, to),
  )

-  if (rows.length === 0) return EMPTY
-
-  const accounts: string[] = []
-  const rateByAccount = new Map<string, number>()
-  const staticRateByAccount = new Map<string, number>()
+  const result = emptyDynamicVatAccounts()
  for (const row of rows) {
    const account = row.account_number
-    const rate = row.default_vat_rate === null
-      ? inferDomesticSalesRate(account, row.account_name)
-      : Number(row.default_vat_rate)
-    if (rate === null || !TAXABLE_RATES.includes(rate)) continue
+    const accountClass = Number(row.account_class ?? account.charAt(0))
+    const configuredRate = row.default_vat_rate === null ? null : Number(row.default_vat_rate)

-    // Checked before the ACCOUNT_TO_BOX skip: these accounts ARE in that map,
-    // which is precisely why they need the rate surfaced separately.
-    if (RUTA_05_STATIC_RATE_ACCOUNTS.has(account)) {
-      staticRateByAccount.set(account, rate)
+    if (isAccountVatTreatment(row.default_vat_treatment)) {
+      if (ACCOUNT_TO_BOX[account]) {
+        if (
+          RUTA_05_STATIC_RATE_ACCOUNTS.has(account) &&
+          configuredRate !== null && TAXABLE_RATES.includes(configuredRate)
+        ) {
+          result.staticRateByAccount.set(account, configuredRate)
+        }
+        continue
+      }
+      const mapping = resolveVatTreatmentRuta(row.default_vat_treatment, accountClass)
+      if (!mapping) continue
+      result.explicitAccounts.add(account)
+      result.mappingByAccount.set(account, mapping)
+      result.accounts.push(account)
+      const rate = configuredRate ?? defaultRateForVatTreatment(row.default_vat_treatment, accountClass)
+      if (mapping.box === 'ruta05' && rate !== null && TAXABLE_RATES.includes(rate)) {
+        result.rateByAccount.set(account, rate)
+      }
+      if (
+        ['ruta20', 'ruta21', 'ruta22', 'ruta23', 'ruta24'].includes(mapping.box) &&
+        rate !== null && TAXABLE_RATES.includes(rate)
+      ) {
+        result.rcBasisRateByAccount.set(account, rate)
+      }
      continue
    }

-    if (ACCOUNT_TO_BOX[account]) continue
+    if (accountClass !== 3) continue
+    const rate = configuredRate ?? inferDomesticSalesRate(account, row.account_name)
+    if (rate === null || !TAXABLE_RATES.includes(rate)) continue
+    if (ACCOUNT_TO_BOX[account]) {
+      if (RUTA_05_STATIC_RATE_ACCOUNTS.has(account)) {
+        result.staticRateByAccount.set(account, rate)
+      }
+      continue
+    }
    if (RUTA_05_EXCLUDED_ACCOUNTS.has(account)) continue
+    result.accounts.push(account)
+    result.mappingByAccount.set(account, { box: 'ruta05', side: 'credit' })
+    result.rateByAccount.set(account, rate)
+  }
+  return result
+}

-    accounts.push(account)
-    rateByAccount.set(account, rate)
+export async function fetchDynamicRuta05Accounts(
+  supabase: SupabaseClient,
+  companyId: string,
+): Promise<Pick<DynamicVatAccounts, 'accounts' | 'rateByAccount' | 'staticRateByAccount'>> {
+  const resolved = await fetchDynamicVatAccounts(supabase, companyId)
+  return {
+    accounts: [...resolved.mappingByAccount]
+      .filter(([account, mapping]) => mapping.box === 'ruta05' && !ACCOUNT_TO_BOX[account])
+      .map(([account]) => account),
+    rateByAccount: resolved.rateByAccount,
+    staticRateByAccount: resolved.staticRateByAccount,
  }
-
-  return { accounts, rateByAccount, staticRateByAccount }
 }
@@ -0,0 +1,84 @@
+import { describe, expect, it } from 'vitest'
+import {
+  defaultRateForVatTreatment,
+  isVatTreatmentValidForAccountClass,
+  resolveVatTreatmentRuta,
+  suggestVatTreatment,
+  vatTreatmentsForAccountClass,
+} from '../account-vat-treatment'
+
+describe('resolveVatTreatmentRuta', () => {
+  it('maps revenue treatments to their momsdeklaration boxes', () => {
+    expect(resolveVatTreatmentRuta('standard_25', 3)).toEqual({ box: 'ruta05', side: 'credit' })
+    expect(resolveVatTreatmentRuta('reverse_charge_domestic', 3)).toEqual({ box: 'ruta41', side: 'credit' })
+    expect(resolveVatTreatmentRuta('reverse_charge_eu_goods', 3)).toEqual({ box: 'ruta35', side: 'credit' })
+    expect(resolveVatTreatmentRuta('reverse_charge_eu_services', 3)).toEqual({ box: 'ruta39', side: 'credit' })
+    expect(resolveVatTreatmentRuta('export_goods', 3)).toEqual({ box: 'ruta36', side: 'credit' })
+    expect(resolveVatTreatmentRuta('export_services', 3)).toEqual({ box: 'ruta40', side: 'credit' })
+    expect(resolveVatTreatmentRuta('exempt', 3)).toEqual({ box: 'ruta42', side: 'credit' })
+    expect(resolveVatTreatmentRuta('vmb', 3)).toEqual({ box: 'ruta07', side: 'credit' })
+    expect(resolveVatTreatmentRuta('rental_voluntary', 3)).toEqual({ box: 'ruta08', side: 'credit' })
+  })
+
+  it('maps purchase treatments by purchase class', () => {
+    expect(resolveVatTreatmentRuta('reverse_charge_eu_goods', 4)).toEqual({ box: 'ruta20', side: 'debit' })
+    expect(resolveVatTreatmentRuta('reverse_charge_eu_services', 4)).toEqual({ box: 'ruta21', side: 'debit' })
+    expect(resolveVatTreatmentRuta('export_services', 5)).toEqual({ box: 'ruta22', side: 'debit' })
+    expect(resolveVatTreatmentRuta('reverse_charge_domestic', 4)).toEqual({ box: 'ruta23', side: 'debit' })
+    expect(resolveVatTreatmentRuta('reverse_charge_domestic', 5)).toEqual({ box: 'ruta24', side: 'debit' })
+    expect(resolveVatTreatmentRuta('export_goods', 4)).toEqual({ box: 'ruta50', side: 'debit' })
+    expect(resolveVatTreatmentRuta('exempt', 4)).toBeNull()
+  })
+})
+
+describe('vat treatment applicability', () => {
+  it('exposes only treatments that resolve for the account class', () => {
+    expect(vatTreatmentsForAccountClass(3)).toContain('vmb')
+    expect(vatTreatmentsForAccountClass(5)).not.toContain('vmb')
+    expect(isVatTreatmentValidForAccountClass('reverse_charge_eu_services', 5)).toBe(true)
+    expect(isVatTreatmentValidForAccountClass('standard_25', 5)).toBe(false)
+  })
+})
+
+describe('suggestVatTreatment', () => {
+  it('suggests the issue examples from labels, not SIE metadata', () => {
+    expect(suggestVatTreatment('3041', 'Försäljning tjänst 25% sv')).toEqual({
+      treatment: 'standard_25', rate: 0.25,
+    })
+    expect(suggestVatTreatment('4056', 'Inköp varor 25% EU')).toEqual({
+      treatment: 'reverse_charge_eu_goods', rate: 0.25,
+    })
+  })
+
+  it('does not guess from an account number alone', () => {
+    expect(suggestVatTreatment('3041', 'Projektintäkt')).toBeNull()
+    expect(suggestVatTreatment('4056', 'Projektkostnad')).toBeNull()
+  })
+
+  it('matches EU as a term, not a substring inside another word', () => {
+    expect(suggestVatTreatment('4056', 'Reumatologiska varor 25%')).toBeNull()
+    expect(suggestVatTreatment('4056', 'Inköp EU-varor 25%')).toEqual({
+      treatment: 'reverse_charge_eu_goods',
+      rate: 0.25,
+    })
+  })
+
+  it('does not assume a purchase-side reverse-charge rate', () => {
+    expect(defaultRateForVatTreatment('reverse_charge_eu_goods', 4)).toBeNull()
+    expect(defaultRateForVatTreatment('reverse_charge_eu_services', 5)).toBeNull()
+    expect(defaultRateForVatTreatment('reverse_charge_domestic', 6)).toBeNull()
+    expect(defaultRateForVatTreatment('export_goods', 4)).toBeNull()
+    expect(suggestVatTreatment('4056', 'Inköp varor EU')).toEqual({
+      treatment: 'reverse_charge_eu_goods',
+      rate: null,
+    })
+  })
+
+  it('does not use a gross account rate for VMB', () => {
+    expect(defaultRateForVatTreatment('vmb', 3)).toBeNull()
+    expect(suggestVatTreatment('3021', 'Försäljning begagnat 25% VMB')).toEqual({
+      treatment: 'vmb',
+      rate: null,
+    })
+  })
+})
@@ -0,0 +1,121 @@
+import type { VatDeclarationRutor } from '@/types'
+
+export const ACCOUNT_VAT_TREATMENTS = [
+  'standard_25', 'reduced_12', 'reduced_6', 'exempt',
+  'reverse_charge_domestic', 'reverse_charge_eu_goods',
+  'reverse_charge_eu_services', 'export_goods', 'export_services',
+  'vmb', 'rental_voluntary',
+] as const
+
+export type AccountVatTreatment = typeof ACCOUNT_VAT_TREATMENTS[number]
+
+export interface AccountVatRutaMapping {
+  box: keyof VatDeclarationRutor
+  side: 'credit' | 'debit'
+}
+
+const REVENUE_RUTA: Record<AccountVatTreatment, keyof VatDeclarationRutor | null> = {
+  standard_25: 'ruta05', reduced_12: 'ruta05', reduced_6: 'ruta05',
+  exempt: 'ruta42', reverse_charge_domestic: 'ruta41',
+  reverse_charge_eu_goods: 'ruta35', reverse_charge_eu_services: 'ruta39',
+  export_goods: 'ruta36', export_services: 'ruta40', vmb: 'ruta07',
+  rental_voluntary: 'ruta08',
+}
+
+export function resolveVatTreatmentRuta(
+  treatment: AccountVatTreatment,
+  accountClass: number,
+): AccountVatRutaMapping | null {
+  if (accountClass === 3) {
+    const box = REVENUE_RUTA[treatment]
+    return box ? { box, side: 'credit' } : null
+  }
+  if (accountClass < 4 || accountClass > 6) return null
+  if (treatment === 'reverse_charge_eu_goods') return { box: 'ruta20', side: 'debit' }
+  if (treatment === 'reverse_charge_eu_services') return { box: 'ruta21', side: 'debit' }
+  if (treatment === 'export_services') return { box: 'ruta22', side: 'debit' }
+  if (treatment === 'reverse_charge_domestic') {
+    return { box: accountClass === 4 ? 'ruta23' : 'ruta24', side: 'debit' }
+  }
+  if (treatment === 'export_goods') return { box: 'ruta50', side: 'debit' }
+  return null
+}
+
+export function defaultRateForVatTreatment(
+  treatment: AccountVatTreatment,
+  accountClass: number,
+): number | null {
+  if (treatment === 'standard_25') return 0.25
+  if (treatment === 'reduced_12') return 0.12
+  if (treatment === 'reduced_6') return 0.06
+  if (treatment === 'exempt') return 0
+  if (treatment === 'rental_voluntary') return 0.25
+  if (treatment === 'vmb') return null
+  return accountClass >= 4 && accountClass <= 6 ? null : 0
+}
+
+export function isAccountVatTreatment(value: unknown): value is AccountVatTreatment {
+  return typeof value === 'string' &&
+    (ACCOUNT_VAT_TREATMENTS as readonly string[]).includes(value)
+}
+
+export function vatTreatmentsForAccountClass(accountClass: number): AccountVatTreatment[] {
+  return ACCOUNT_VAT_TREATMENTS.filter(
+    (treatment) => resolveVatTreatmentRuta(treatment, accountClass) !== null,
+  )
+}
+
+export function isVatTreatmentValidForAccountClass(
+  treatment: AccountVatTreatment,
+  accountClass: number,
+): boolean {
+  return resolveVatTreatmentRuta(treatment, accountClass) !== null
+}
+
+export interface SuggestedVatTreatment {
+  treatment: AccountVatTreatment
+  rate: number | null
+}
+
+/**
+ * Suggest a VAT treatment from a SIE account label. SIE #SRU and #KTYP are
+ * deliberately excluded: neither record carries a momsdeklaration treatment.
+ * Suggestions are persisted only after the user reviews the import mapping.
+ */
+export function suggestVatTreatment(
+  accountNumber: string,
+  accountName: string,
+): SuggestedVatTreatment | null {
+  const accountClass = Number(accountNumber.charAt(0))
+  if (accountClass < 3 || accountClass > 6) return null
+  const name = accountName.toLocaleLowerCase('sv-SE')
+  const percent = /\b(25|12|6)\s*%/.exec(name)
+  const rate = percent ? Number(percent[1]) / 100 : null
+
+  if (accountClass === 3) {
+    if (/vmb|vinstmarginal/.test(name)) return { treatment: 'vmb', rate: null }
+    if (/hyra|uthyrning/.test(name) && /frivillig/.test(name)) {
+      return { treatment: 'rental_voluntary', rate: rate ?? 0.25 }
+    }
+    if (/omvänd/.test(name)) return { treatment: 'reverse_charge_domestic', rate: 0 }
+    if (/momsfri|utan moms/.test(name)) return { treatment: 'exempt', rate: 0 }
+    if (/export|utanför eu/.test(name) && /var/.test(name)) return { treatment: 'export_goods', rate: 0 }
+    if (/export|utanför eu/.test(name) && /tjänst|tjanst/.test(name)) return { treatment: 'export_services', rate: 0 }
+    if (/\beu\b/.test(name) && /var/.test(name)) return { treatment: 'reverse_charge_eu_goods', rate: 0 }
+    if (/\beu\b/.test(name) && /tjänst|tjanst/.test(name)) return { treatment: 'reverse_charge_eu_services', rate: 0 }
+    if (/försälj|forsalj|intäkt|intakt/.test(name) && percent) {
+      return {
+        treatment: rate === 0.12 ? 'reduced_12' : rate === 0.06 ? 'reduced_6' : 'standard_25',
+        rate,
+      }
+    }
+    return null
+  }
+
+  if (/omvänd/.test(name) && /sverige|svensk|inrikes/.test(name)) return { treatment: 'reverse_charge_domestic', rate }
+  if (/import|utanför eu/.test(name) && /var/.test(name)) return { treatment: 'export_goods', rate }
+  if (/utanför eu/.test(name) && /tjänst|tjanst/.test(name)) return { treatment: 'export_services', rate }
+  if (/\beu\b/.test(name) && /var/.test(name)) return { treatment: 'reverse_charge_eu_goods', rate }
+  if (/\beu\b/.test(name) && /tjänst|tjanst/.test(name)) return { treatment: 'reverse_charge_eu_services', rate }
+  return null
+}
@@ -4919,7 +4919,27 @@
    "toast_pruned_with_skipped": "{deleted} accounts deleted, {skipped} skipped",
    "toast_prune_failed": "Could not clean up the chart of accounts",
    "bas_version_chip": "BAS 2026",
-    "footer_note": "Showing {shown} of {total} accounts, grouped by BAS class. SRU codes carry through to the income tax return."
+    "footer_note": "Showing {shown} of {total} accounts, grouped by BAS class. SRU codes carry through to the income tax return.",
+    "vat_treatment_label": "VAT treatment for the VAT return",
+    "vat_treatment_none": "Use BAS default",
+    "vat_treatment_help": "Controls which VAT return box receives the account balance. A selected treatment overrides the BAS default.",
+    "vat_treatment_not_applicable": "VAT treatment is available for revenue and purchase accounts in classes 3-6.",
+    "vat_treatment_standard_25": "Swedish sales, 25% (box 05)",
+    "vat_treatment_reduced_12": "Swedish sales, 12% (box 05)",
+    "vat_treatment_reduced_6": "Swedish sales, 6% (box 05)",
+    "vat_treatment_exempt": "VAT-exempt sales (box 42)",
+    "vat_treatment_reverse_charge_domestic": "Domestic reverse charge",
+    "vat_treatment_reverse_charge_eu_goods": "EU goods",
+    "vat_treatment_reverse_charge_eu_services": "EU services",
+    "vat_treatment_export_goods": "Export or import of goods",
+    "vat_treatment_export_services": "Services outside the EU",
+    "vat_treatment_vmb": "Margin scheme (box 07)",
+    "vat_treatment_rental_voluntary": "Voluntary VAT on rental income (box 08)",
+    "vat_rate_label": "VAT rate",
+    "vat_rate_none": "None",
+    "vat_review_filter": "{count} VAT treatments to review",
+    "vat_treatment_column": "VAT treatment",
+    "vat_treatment_confirm": "Confirm"
  },
  "dimensions": {
    "new_value": "New value",
@@ -6854,6 +6874,9 @@
    "reveal_bridge": "The history is in place. What's missing is the present: the bank.",
    "reveal_cta_bank": "Connect the bank",
    "reveal_cta_open": "Open Accounted",
+    "vat_review_title": "{count, plural, one {# account has no VAT treatment} other {# accounts have no VAT treatment}}",
+    "vat_review_description": "Set VAT treatments on imported revenue and purchase accounts so the VAT return uses the correct boxes.",
+    "vat_review_action": "Review VAT treatments in the chart",
    "export_title": "Export",
    "export_subtitle": "Download your bookkeeping as a SIE file or back it up to Google Drive",
    "tab_import": "Import",
@@ -4919,7 +4919,27 @@
    "toast_pruned_with_skipped": "{deleted} konton togs bort, {skipped} hoppades över",
    "toast_prune_failed": "Kunde inte rensa kontoplanen",
    "bas_version_chip": "BAS 2026",
-    "footer_note": "Visar {shown} av {total} konton, grupperade per BAS-klass. SRU-koderna följer med till inkomstdeklarationen."
+    "footer_note": "Visar {shown} av {total} konton, grupperade per BAS-klass. SRU-koderna följer med till inkomstdeklarationen.",
+    "vat_treatment_label": "Momskod för momsdeklarationen",
+    "vat_treatment_none": "Använd BAS-standard",
+    "vat_treatment_help": "Styr vilken ruta kontots belopp hamnar i. En vald momskod går före BAS-standarden.",
+    "vat_treatment_not_applicable": "Momskod kan väljas för intäkts- och inköpskonton i klass 3-6.",
+    "vat_treatment_standard_25": "Försäljning Sverige, 25 % (ruta 05)",
+    "vat_treatment_reduced_12": "Försäljning Sverige, 12 % (ruta 05)",
+    "vat_treatment_reduced_6": "Försäljning Sverige, 6 % (ruta 05)",
+    "vat_treatment_exempt": "Momsfri försäljning (ruta 42)",
+    "vat_treatment_reverse_charge_domestic": "Omvänd skattskyldighet Sverige",
+    "vat_treatment_reverse_charge_eu_goods": "EU-varor",
+    "vat_treatment_reverse_charge_eu_services": "EU-tjänster",
+    "vat_treatment_export_goods": "Export eller import av varor",
+    "vat_treatment_export_services": "Tjänster utanför EU",
+    "vat_treatment_vmb": "Vinstmarginalbeskattning (ruta 07)",
+    "vat_treatment_rental_voluntary": "Frivillig moms på uthyrning (ruta 08)",
+    "vat_rate_label": "Momssats",
+    "vat_rate_none": "Ingen",
+    "vat_review_filter": "{count} momskoder att granska",
+    "vat_treatment_column": "Momskod",
+    "vat_treatment_confirm": "Bekräfta"
  },
  "dimensions": {
    "new_value": "Nytt värde",
@@ -6854,6 +6874,9 @@
    "reveal_bridge": "Historiken är på plats. Det som saknas är nuet: banken.",
    "reveal_cta_bank": "Koppla banken",
    "reveal_cta_open": "Öppna Accounted",
+    "vat_review_title": "{count, plural, one {# konto saknar momskod} other {# konton saknar momskod}}",
+    "vat_review_description": "Sätt momskod på importerade intäkts- och inköpskonton så att momsdeklarationen hamnar i rätt ruta.",
+    "vat_review_action": "Granska momskoder i kontoplanen",
    "export_title": "Exportera",
    "export_subtitle": "Ladda ner bokföringen som SIE-fil eller säkerhetskopia till Google Drive",
    "tab_import": "Importera",
@@ -0,0 +1,19 @@
+ALTER TABLE public.chart_of_accounts
+  ADD COLUMN IF NOT EXISTS default_vat_treatment text;
+
+ALTER TABLE public.chart_of_accounts
+  DROP CONSTRAINT IF EXISTS chart_of_accounts_default_vat_treatment_check;
+
+ALTER TABLE public.chart_of_accounts
+  ADD CONSTRAINT chart_of_accounts_default_vat_treatment_check
+  CHECK (default_vat_treatment IS NULL OR default_vat_treatment IN (
+    'standard_25', 'reduced_12', 'reduced_6', 'exempt',
+    'reverse_charge_domestic', 'reverse_charge_eu_goods',
+    'reverse_charge_eu_services', 'export_goods', 'export_services',
+    'vmb', 'rental_voluntary'
+  ));
+
+COMMENT ON COLUMN public.chart_of_accounts.default_vat_treatment IS
+  'Per-account momsdeklaration treatment. Explicit values override the built-in BAS account mapping.';
+
+NOTIFY pgrst, 'reload schema';
@@ -0,0 +1,47 @@
+import { describe, expect, it } from 'vitest'
+import { seedCompany } from '@/tests/pg/fixtures'
+import { getPool } from '@/tests/pg/setup'
+
+async function setTreatment(companyId: string, treatment: string | null) {
+  return getPool().query(
+    `UPDATE public.chart_of_accounts
+     SET default_vat_treatment = $2
+     WHERE company_id = $1 AND account_number = '3013'`,
+    [companyId, treatment],
+  )
+}
+
+async function insertAccount(companyId: string, userId: string) {
+  return getPool().query(
+    `INSERT INTO public.chart_of_accounts
+       (user_id, company_id, account_number, account_name, account_class,
+        account_group, account_type, normal_balance, plan_type,
+        is_system_account)
+     VALUES ($1, $2, '3013', 'Test account', 3, '30', 'revenue', 'credit',
+       'full_bas', false)
+     RETURNING account_number`,
+    [userId, companyId],
+  )
+}
+
+describe('chart_of_accounts.default_vat_treatment', () => {
+  it('accepts every supported treatment and NULL', async () => {
+    const { companyId, userId } = await seedCompany()
+    expect((await insertAccount(companyId, userId)).rowCount).toBe(1)
+    const treatments = [
+      'standard_25', 'reduced_12', 'reduced_6', 'exempt',
+      'reverse_charge_domestic', 'reverse_charge_eu_goods',
+      'reverse_charge_eu_services', 'export_goods', 'export_services',
+      'vmb', 'rental_voluntary', null,
+    ]
+    for (const treatment of treatments) {
+      await expect(setTreatment(companyId, treatment)).resolves.toMatchObject({ rowCount: 1 })
+    }
+  })
+
+  it('rejects unknown treatments', async () => {
+    const { companyId, userId } = await seedCompany()
+    expect((await insertAccount(companyId, userId)).rowCount).toBe(1)
+    await expect(setTreatment(companyId, 'unknown')).rejects.toThrow()
+  })
+})
@@ -1734,6 +1734,7 @@ export interface BASAccount {
  // Per-account default VAT rate for booking lines (0/0.06/0.12/0.25).
  // null = no default (line keeps its own rate). Öresavrundning (3740) = 0.
  default_vat_rate: number | null
+  default_vat_treatment: import('@/lib/vat/account-vat-treatment').AccountVatTreatment | null
  description: string | null
  sru_code: string | null
  k2_excluded: boolean