diff --git a/app/api/salary/runs/[id]/payment/pain001/route.ts b/app/api/salary/runs/[id]/payment/pain001/route.ts
index 96eb20bc..f0ef2019 100644
--- a/app/api/salary/runs/[id]/payment/pain001/route.ts
+++ b/app/api/salary/runs/[id]/payment/pain001/route.ts
@@ -3,6 +3,7 @@ import { ensureInitialized } from '@/lib/init'
 import { withRouteContext } from '@/lib/api/with-route-context'
 import { generatePain001 } from '@/lib/salary/payment/pain001-generator'
 import { effectiveNetPayout } from '@/lib/salary/payment/effective-net'
+import { normalizeBankNumber, lookupBicByClearing, lookupBicByBankName } from '@/lib/salary/payment/bank-account'
 import { getBranding } from '@/lib/branding/service'
 import type { Pain001CompanyData, Pain001Employee } from '@/lib/salary/payment/pain001-generator'
 
@@ -47,7 +48,7 @@ export const GET = withRouteContext<{ params: Promise<{ id: string }> }>(
 
     const { data: settings } = await supabase
       .from('company_settings')
-      .select('company_name, iban, bic')
+      .select('company_name, iban, bic, clearing_number, bank_name')
       .eq('company_id', companyId)
       .single()
 
@@ -55,8 +56,31 @@ export const GET = withRouteContext<{ params: Promise<{ id: string }> }>(
       return NextResponse.json({ error: 'Företag hittades inte' }, { status: 404 })
     }
 
-    if (!settings?.iban || !settings?.bic) {
-      return NextResponse.json({ error: 'IBAN och BIC krävs i företagsinställningar för betalfil' }, { status: 400 })
+    if (!settings) {
+      return NextResponse.json({ error: 'Företagsinställningar saknas' }, { status: 400 })
+    }
+
+    // Debtor (company) account: the company's own IBAN, the canonical payer form
+    // every Swedish bank accepts. Set under Inställningar → Fakturering.
+    const senderIban = (settings.iban ?? '').replace(/\s/g, '').toUpperCase()
+    if (!senderIban) {
+      return NextResponse.json(
+        { error: 'Företagets IBAN saknas i företagsinställningar. Fyll i det under Inställningar → Fakturering för att skapa betalfil (ISO 20022).' },
+        { status: 400 },
+      )
+    }
+
+    // Debtor bank BIC: use the saved BIC, otherwise derive it from the clearing
+    // number (or bank name) the company already entered, so most users only need
+    // to fill in the IBAN. Required by the receiving bank.
+    const senderBic = settings.bic?.trim()
+      || lookupBicByClearing(normalizeBankNumber(settings.clearing_number))
+      || lookupBicByBankName(settings.bank_name)
+    if (!senderBic) {
+      return NextResponse.json(
+        { error: 'Företagsbankens BIC saknas och kunde inte härledas. Fyll i BIC under Inställningar → Fakturering för att skapa betalfil.' },
+        { status: 400 },
+      )
     }
 
     // Load employees
@@ -89,8 +113,8 @@ export const GET = withRouteContext<{ params: Promise<{ id: string }> }>(
       // not the frozen onboarding companies.name.
       name: settings.company_name || company.name,
       orgNumber: company.org_number || '',
-      iban: settings.iban,
-      bic: settings.bic,
+      iban: senderIban,
+      bic: senderBic,
     }
 
     const employees: Pain001Employee[] = runEmployees
diff --git a/components/settings/BankDetailsForm.tsx b/components/settings/BankDetailsForm.tsx
index 5c8f6a89..840537c9 100644
--- a/components/settings/BankDetailsForm.tsx
+++ b/components/settings/BankDetailsForm.tsx
@@ -21,6 +21,8 @@ export function BankDetailsForm({ settings }: BankDetailsFormProps) {
   const [clearingError, setClearingError] = useState<string | null>(null)
   const [accountNumberError, setAccountNumberError] = useState<string | null>(null)
   const [swishError, setSwishError] = useState<string | null>(null)
+  const [ibanError, setIbanError] = useState<string | null>(null)
+  const [bicError, setBicError] = useState<string | null>(null)
   const hasBankingExtension = ENABLED_EXTENSION_IDS.has('enable-banking')
 
   return (
@@ -146,6 +148,45 @@ export function BankDetailsForm({ settings }: BankDetailsFormProps) {
           {swishError && <p className="text-xs text-destructive">{swishError}</p>}
         </div>
       </div>
+
+      <div className="grid grid-cols-1 sm:grid-cols-3 gap-4">
+        <div className="space-y-2 sm:col-span-2">
+          <Label htmlFor="iban">{t('iban_label')}</Label>
+          <Input
+            id="iban"
+            name="iban"
+            placeholder="SE00 0000 0000 0000 0000 0000"
+            defaultValue={settings.iban || ''}
+            onBlur={(e) => {
+              const val = e.target.value.replace(/\s/g, '').toUpperCase()
+              if (!val) { setIbanError(null); e.target.value = ''; return }
+              e.target.value = val
+              setIbanError(/^SE\d{22}$/.test(val) ? null : t('iban_error'))
+            }}
+          />
+          {ibanError
+            ? <p className="text-xs text-destructive">{ibanError}</p>
+            : <p className="text-xs text-muted-foreground">{t('iban_hint')}</p>}
+        </div>
+
+        <div className="space-y-2">
+          <Label htmlFor="bic">{t('bic_label')}</Label>
+          <Input
+            id="bic"
+            name="bic"
+            placeholder={t('bic_placeholder')}
+            maxLength={11}
+            defaultValue={settings.bic || ''}
+            onBlur={(e) => {
+              const val = e.target.value.replace(/\s/g, '').toUpperCase()
+              if (!val) { setBicError(null); e.target.value = ''; return }
+              e.target.value = val
+              setBicError(/^[A-Z]{6}[A-Z0-9]{2}([A-Z0-9]{3})?$/.test(val) ? null : t('bic_error'))
+            }}
+          />
+          {bicError && <p className="text-xs text-destructive">{bicError}</p>}
+        </div>
+      </div>
     </section>
   )
 }
@@ -158,6 +199,8 @@ export function validateBankFields(formData: FormData): { field: string; message
   const bankgiro = (formData.get('bankgiro') as string || '').trim()
   const plusgiro = (formData.get('plusgiro') as string || '').trim()
   const swish = normaliseSwish(formData.get('swish') as string)
+  const iban = (formData.get('iban') as string || '').replace(/\s/g, '').toUpperCase()
+  const bic = (formData.get('bic') as string || '').replace(/\s/g, '').toUpperCase()
 
   if (clearing && !/^\d{4,5}$/.test(clearing)) {
     errors.push({ field: 'clearing_number', message: 'Clearingnummer måste vara 4-5 siffror' })
@@ -174,5 +217,11 @@ export function validateBankFields(formData: FormData): { field: string; message
   if (swish && !isValidSwish(swish)) {
     errors.push({ field: 'swish', message: 'Ogiltigt Swish-nummer (företagsnummer 123XXXXXXX eller mobilnummer 07XXXXXXXX)' })
   }
+  if (iban && !/^SE\d{22}$/.test(iban)) {
+    errors.push({ field: 'iban', message: 'Ogiltigt IBAN (SE följt av 22 siffror)' })
+  }
+  if (bic && !/^[A-Z]{6}[A-Z0-9]{2}([A-Z0-9]{3})?$/.test(bic)) {
+    errors.push({ field: 'bic', message: 'Ogiltig BIC/SWIFT (8 eller 11 tecken)' })
+  }
   return errors
 }
diff --git a/components/settings/sections/InvoicingSettingsContent.tsx b/components/settings/sections/InvoicingSettingsContent.tsx
index 77d0d3be..71bc777a 100644
--- a/components/settings/sections/InvoicingSettingsContent.tsx
+++ b/components/settings/sections/InvoicingSettingsContent.tsx
@@ -43,6 +43,8 @@ export function InvoicingSettingsContent() {
         ? formatPlusgiroNumber((formData.get('plusgiro') as string).trim())
         : null,
       swish: normaliseSwish(formData.get('swish') as string) || null,
+      iban: (formData.get('iban') as string || '').replace(/\s/g, '').toUpperCase() || null,
+      bic: (formData.get('bic') as string || '').replace(/\s/g, '').toUpperCase() || null,
       invoice_prefix: (formData.get('invoice_prefix') as string) || null,
       next_invoice_number: parseInt(formData.get('next_invoice_number') as string) || 1,
       next_arrival_number: parseInt(formData.get('next_arrival_number') as string) || 1,
diff --git a/lib/api/schemas.ts b/lib/api/schemas.ts
index c5ad6748..b6e587ca 100644
--- a/lib/api/schemas.ts
+++ b/lib/api/schemas.ts
@@ -1363,8 +1363,8 @@ export const UpdateSettingsSchema = z.object({
     )
     .nullable()
     .optional(),
-  iban: z.string().optional(),
-  bic: z.string().optional(),
+  iban: z.string().regex(/^SE\d{22}$/, 'Ogiltigt IBAN (SE följt av 22 siffror)').nullable().optional().or(z.literal('')),
+  bic: z.string().regex(/^[A-Z]{6}[A-Z0-9]{2}([A-Z0-9]{3})?$/, 'Ogiltig BIC/SWIFT (8 eller 11 tecken)').nullable().optional().or(z.literal('')),
   accounting_method: AccountingMethodSchema.optional(),
   invoice_prefix: z.string().nullable().optional(),
   next_invoice_number: z.number().int().positive().optional(),
diff --git a/lib/errors/__tests__/get-error-message.test.ts b/lib/errors/__tests__/get-error-message.test.ts
index e23d05c1..639111d0 100644
--- a/lib/errors/__tests__/get-error-message.test.ts
+++ b/lib/errors/__tests__/get-error-message.test.ts
@@ -147,6 +147,38 @@ describe('getErrorMessage: accumulated validation details', () => {
   })
 })
 
+describe('getErrorMessage: payment-file route messages surface (issue #945)', () => {
+  // These specific { error: '...' } strings previously collapsed to the generic
+  // HTTP-400 message because isSwedishUserMessage did not recognize "krävs" /
+  // "saknar", so the user learned nothing about why the betalfil failed.
+  it('surfaces a "saknar bankkontouppgifter" message instead of the generic 400', () => {
+    const msg = getErrorMessage(
+      { error: '2 anställd(a) saknar bankkontouppgifter' },
+      { context: 'salary', statusCode: 400 },
+    )
+    expect(msg).toBe('2 anställd(a) saknar bankkontouppgifter')
+    expect(msg).not.toBe('Förfrågan innehåller ogiltiga uppgifter.')
+  })
+
+  it('surfaces a "... krävs ..." message instead of the generic 400', () => {
+    const msg = getErrorMessage(
+      { error: 'Momsregistreringsnummer krävs när företaget är momsregistrerat (ML 11 kap. 8§)' },
+      { context: 'settings', statusCode: 400 },
+    )
+    expect(msg).toContain('krävs')
+    expect(msg).not.toBe('Förfrågan innehåller ogiltiga uppgifter.')
+  })
+
+  it('surfaces the missing company bank-account message', () => {
+    const msg = getErrorMessage(
+      { error: 'Företagets bankkonto (clearingnummer och kontonummer) saknas i företagsinställningar. Fyll i det under Inställningar → Fakturering för att skapa betalfil.' },
+      { context: 'salary', statusCode: 400 },
+    )
+    expect(msg).toContain('Företagets bankkonto')
+    expect(msg).not.toBe('Förfrågan innehåller ogiltiga uppgifter.')
+  })
+})
+
 describe('getErrorMessage: existing patterns still work', () => {
   it('regex match for "Entry date ... outside fiscal period" on plain string', () => {
     const msg = getErrorMessage('Entry date 2024-06-15 is outside fiscal period "FY 2025"')
diff --git a/lib/errors/get-error-message.ts b/lib/errors/get-error-message.ts
index 85a25b3a..62491e6f 100644
--- a/lib/errors/get-error-message.ts
+++ b/lib/errors/get-error-message.ts
@@ -166,6 +166,8 @@ function isSwedishUserMessage(message: string): boolean {
     /försök igen/i,
     /ogiltigt?/i,
     /saknas/i,
+    /saknar/i,
+    /krävs/i,
     /måste/i,
     /redan finns/i,
     /gick fel/i,
diff --git a/lib/salary/__tests__/pain001.test.ts b/lib/salary/__tests__/pain001.test.ts
index 9c04f897..ebe01172 100644
--- a/lib/salary/__tests__/pain001.test.ts
+++ b/lib/salary/__tests__/pain001.test.ts
@@ -40,10 +40,18 @@ describe('generatePain001', () => {
     const xml = generatePain001(company, employees, options)
 
     expect(xml).toContain('<Nm>Test AB</Nm>')
-    expect(xml).toContain('SE1234567890123456789012')
     expect(xml).toContain('ESSESESS')
   })
 
+  it('identifies the debtor (company) by its own IBAN', () => {
+    const xml = generatePain001(company, employees, options)
+
+    // The payer is the company's IBAN, inside DbtrAcct.
+    expect(xml).toContain('<IBAN>SE1234567890123456789012</IBAN>')
+    // Employees are still domestic BBAN (clearing+account), never IBAN.
+    expect(xml).toContain('<Othr><Id>56781234567890</Id></Othr>')
+  })
+
   it('includes SALA category purpose for salary', () => {
     const xml = generatePain001(company, employees, options)
     expect(xml).toContain('<Cd>SALA</Cd>')
diff --git a/lib/salary/payment/__tests__/bank-account.test.ts b/lib/salary/payment/__tests__/bank-account.test.ts
index b6b3604e..5a0bb308 100644
--- a/lib/salary/payment/__tests__/bank-account.test.ts
+++ b/lib/salary/payment/__tests__/bank-account.test.ts
@@ -5,6 +5,8 @@ import {
   isValidAccount,
   validateEmployeeBankAccount,
   lookupBankByClearing,
+  lookupBicByClearing,
+  lookupBicByBankName,
 } from '@/lib/salary/payment/bank-account'
 
 describe('normalizeBankNumber', () => {
@@ -100,3 +102,37 @@ describe('lookupBankByClearing', () => {
     expect(lookupBankByClearing('')).toBeNull()
   })
 })
+
+describe('lookupBicByClearing', () => {
+  it('maps clearing numbers to the bank BIC', () => {
+    expect(lookupBicByClearing('5000')).toBe('ESSESESS')  // SEB
+    expect(lookupBicByClearing('6789')).toBe('HANDSESS')  // Handelsbanken
+    expect(lookupBicByClearing('7123')).toBe('SWEDSESS')  // Swedbank
+    expect(lookupBicByClearing('3000')).toBe('NDEASESS')  // Nordea
+    expect(lookupBicByClearing('1234')).toBe('DABASESX')  // Danske Bank
+  })
+  it('maps a 5-digit Swedbank clearing via its 8xxx prefix', () => {
+    expect(lookupBicByClearing('83279')).toBe('SWEDSESS')
+  })
+  it('returns null for unknown ranges rather than guessing a BIC', () => {
+    expect(lookupBicByClearing('9999')).toBeNull()
+    expect(lookupBicByClearing('123')).toBeNull()
+    expect(lookupBicByClearing('')).toBeNull()
+  })
+})
+
+describe('lookupBicByBankName', () => {
+  it('resolves banks outside the clearing table by name', () => {
+    expect(lookupBicByBankName('Länsförsäkringar')).toBe('ELLFSESS')
+    expect(lookupBicByBankName('Skandiabanken')).toBe('SKIASESS')
+  })
+  it('matches on a normalized substring', () => {
+    expect(lookupBicByBankName('Danske Bank Sverige')).toBe('DABASESX')
+    expect(lookupBicByBankName('  SEB  ')).toBe('ESSESESS')
+  })
+  it('returns null for unknown or empty names', () => {
+    expect(lookupBicByBankName('Min Lokala Bank')).toBeNull()
+    expect(lookupBicByBankName('')).toBeNull()
+    expect(lookupBicByBankName(null)).toBeNull()
+  })
+})
diff --git a/lib/salary/payment/bank-account.ts b/lib/salary/payment/bank-account.ts
index e50fd899..bf1f34ed 100644
--- a/lib/salary/payment/bank-account.ts
+++ b/lib/salary/payment/bank-account.ts
@@ -130,18 +130,18 @@ export function validateEmployeeBankAccount(
  * Ranges are matched on the leading 4 digits, so a 5-digit Swedbank clearing
  * (8xxxx) maps via its 8xxx prefix.
  */
-const BANK_CLEARING_RANGES: ReadonlyArray<{ min: number; max: number; bank: string }> = [
-  { min: 1100, max: 1199, bank: 'Nordea' },
-  { min: 1200, max: 1399, bank: 'Danske Bank' },
-  { min: 1400, max: 2099, bank: 'Nordea' },
-  { min: 2400, max: 2499, bank: 'Danske Bank' },
-  { min: 3000, max: 3399, bank: 'Nordea' },
-  { min: 5000, max: 5999, bank: 'SEB' },
-  { min: 6000, max: 6999, bank: 'Handelsbanken' },
-  { min: 7000, max: 7999, bank: 'Swedbank' },
-  { min: 8000, max: 8999, bank: 'Swedbank/Sparbanken' },
-  { min: 9500, max: 9549, bank: 'Nordea (Plusgirot)' },
-  { min: 9960, max: 9969, bank: 'Nordea (Plusgirot)' },
+const BANK_CLEARING_RANGES: ReadonlyArray<{ min: number; max: number; bank: string; bic: string }> = [
+  { min: 1100, max: 1199, bank: 'Nordea', bic: 'NDEASESS' },
+  { min: 1200, max: 1399, bank: 'Danske Bank', bic: 'DABASESX' },
+  { min: 1400, max: 2099, bank: 'Nordea', bic: 'NDEASESS' },
+  { min: 2400, max: 2499, bank: 'Danske Bank', bic: 'DABASESX' },
+  { min: 3000, max: 3399, bank: 'Nordea', bic: 'NDEASESS' },
+  { min: 5000, max: 5999, bank: 'SEB', bic: 'ESSESESS' },
+  { min: 6000, max: 6999, bank: 'Handelsbanken', bic: 'HANDSESS' },
+  { min: 7000, max: 7999, bank: 'Swedbank', bic: 'SWEDSESS' },
+  { min: 8000, max: 8999, bank: 'Swedbank/Sparbanken', bic: 'SWEDSESS' },
+  { min: 9500, max: 9549, bank: 'Nordea (Plusgirot)', bic: 'NDEASESS' },
+  { min: 9960, max: 9969, bank: 'Nordea (Plusgirot)', bic: 'NDEASESS' },
 ]
 
 /** Bank name for a (partial) clearing number, or null when not confidently known. */
@@ -153,3 +153,47 @@ export function lookupBankByClearing(clearingRaw: string | null | undefined): st
   const hit = BANK_CLEARING_RANGES.find((r) => first4 >= r.min && first4 <= r.max)
   return hit ? hit.bank : null
 }
+
+/**
+ * Bank BIC (SWIFT) for a clearing number, or null when the clearing is not in
+ * the table above. Used to fill the debtor agent (DbtrAgt) in the pain.001
+ * salary payment file without asking the company to type its BIC by hand: the
+ * clearing number it already entered for the debtor account deterministically
+ * identifies the bank. Only confidently-known, long-stable ranges are covered;
+ * an unknown clearing returns null so the caller can fall back or fail loudly
+ * rather than emit a guessed BIC into a real payment instruction.
+ */
+export function lookupBicByClearing(clearingRaw: string | null | undefined): string | null {
+  const clearing = normalizeBankNumber(clearingRaw)
+  if (clearing.length < 4) return null
+  const first4 = Number.parseInt(clearing.slice(0, 4), 10)
+  if (Number.isNaN(first4)) return null
+  const hit = BANK_CLEARING_RANGES.find((r) => first4 >= r.min && first4 <= r.max)
+  return hit ? hit.bic : null
+}
+
+/**
+ * Fallback BIC lookup by the free-text bank name saved in company settings, for
+ * the (rare) banks not covered by the clearing ranges above (e.g.
+ * Länsförsäkringar, Skandiabanken). Matched on a normalized substring so
+ * "Danske Bank Sverige" still resolves. Only BICs we are confident about are
+ * listed; anything else returns null. Never guess a BIC for a real payment.
+ */
+const BANK_NAME_BIC: ReadonlyArray<{ match: string; bic: string }> = [
+  { match: 'handelsbanken', bic: 'HANDSESS' },
+  { match: 'länsförsäkringar', bic: 'ELLFSESS' },
+  { match: 'lansforsakringar', bic: 'ELLFSESS' },
+  { match: 'skandia', bic: 'SKIASESS' },
+  { match: 'swedbank', bic: 'SWEDSESS' },
+  { match: 'sparbank', bic: 'SWEDSESS' },
+  { match: 'danske', bic: 'DABASESX' },
+  { match: 'nordea', bic: 'NDEASESS' },
+  { match: 'seb', bic: 'ESSESESS' },
+]
+
+export function lookupBicByBankName(nameRaw: string | null | undefined): string | null {
+  const name = (nameRaw ?? '').trim().toLowerCase()
+  if (!name) return null
+  const hit = BANK_NAME_BIC.find((b) => name.includes(b.match))
+  return hit ? hit.bic : null
+}
diff --git a/lib/salary/payment/pain001-generator.ts b/lib/salary/payment/pain001-generator.ts
index f3efc8fe..d2c2b415 100644
--- a/lib/salary/payment/pain001-generator.ts
+++ b/lib/salary/payment/pain001-generator.ts
@@ -10,8 +10,8 @@
 export interface Pain001CompanyData {
   name: string
   orgNumber: string       // NNNNNN-NNNN
-  iban: string            // SE + 22 digits
-  bic: string             // SWIFT/BIC code
+  iban: string            // SE + 22 digits (the company's own account)
+  bic: string             // debtor bank SWIFT/BIC
 }
 
 export interface Pain001Employee {
@@ -87,6 +87,9 @@ export function generatePain001(
   lines.push('      </Dbtr>')
   lines.push('      <DbtrAcct>')
   lines.push('        <Id>')
+  // The company (debtor) is identified by its own IBAN: the canonical form every
+  // Swedish bank accepts for the payer. Employees (creditors) stay on domestic
+  // clearing+account below, which is what Swedish payroll actually collects.
   lines.push(`          <IBAN>${escapeXml(company.iban)}</IBAN>`)
   lines.push('        </Id>')
   lines.push('        <Ccy>SEK</Ccy>')
diff --git a/messages/en.json b/messages/en.json
index 6f230cd0..3d9b9505 100644
--- a/messages/en.json
+++ b/messages/en.json
@@ -1330,7 +1330,13 @@
     "plusgiro_error": "Invalid plusgiro number",
     "swish_label": "Swish",
     "swish_placeholder": "123 XXX XX XX or 07X XXX XX XX",
-    "swish_error": "Invalid Swish number (business number 123XXXXXXX or mobile number 07XXXXXXXX)"
+    "swish_error": "Invalid Swish number (business number 123XXXXXXX or mobile number 07XXXXXXXX)",
+    "iban_label": "IBAN",
+    "iban_error": "Invalid IBAN (SE followed by 22 digits)",
+    "iban_hint": "Required for the payment file (ISO 20022) when paying salaries",
+    "bic_label": "BIC/SWIFT",
+    "bic_placeholder": "Filled in automatically",
+    "bic_error": "Invalid BIC/SWIFT (8 or 11 characters)"
   },
   "settings_invoice_form": {
     "default_our_reference_label": "Default \"Our reference\"",
diff --git a/messages/sv.json b/messages/sv.json
index 3bf843fd..cac13a5e 100644
--- a/messages/sv.json
+++ b/messages/sv.json
@@ -1330,7 +1330,13 @@
     "plusgiro_error": "Ogiltigt plusgironummer",
     "swish_label": "Swish",
     "swish_placeholder": "123 XXX XX XX eller 07X XXX XX XX",
-    "swish_error": "Ogiltigt Swish-nummer (företagsnummer 123XXXXXXX eller mobilnummer 07XXXXXXXX)"
+    "swish_error": "Ogiltigt Swish-nummer (företagsnummer 123XXXXXXX eller mobilnummer 07XXXXXXXX)",
+    "iban_label": "IBAN",
+    "iban_error": "Ogiltigt IBAN (SE följt av 22 siffror)",
+    "iban_hint": "Krävs för betalfil (ISO 20022) vid löneutbetalning",
+    "bic_label": "BIC/SWIFT",
+    "bic_placeholder": "Fylls i automatiskt",
+    "bic_error": "Ogiltig BIC/SWIFT (8 eller 11 tecken)"
   },
   "settings_invoice_form": {
     "default_our_reference_label": "Standard för Vår referens",