fix(tax): representation meal warning inverted the 2017 VAT rule (#313) (#1106)

The restaurant/lunch warning claimed 'Momsen är inte avdragsgill sedan
2017', which is legally backwards. The 2017 reform (Prop. 2016/17:1)
abolished the income-tax deduction for representation meals (IL 16 kap
2 §) but retained the VAT deduction on a base of up to 300 SEK per
person excl. VAT, now ML 2023:200 13 kap 24-25 §§. The old 'ML 8:9'
citation pointed at the repealed ML 1994:200.

Verified against the swedish-vat compliance skill before rewording.
Adds regression tests pinning the corrected message and legalBasis.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

lib/tax/__tests__/expense-warnings.test.ts

@@ -0,0 +1,40 @@
+import { describe, it, expect } from 'vitest'
+import { checkExpenseWarnings } from '../expense-warnings'
+
+describe('checkExpenseWarnings: representation meals', () => {
+  it('states that the VAT deduction is retained on a 300 kr/person base (2017 reform inverted this before, issue #313)', () => {
+    const warnings = checkExpenseWarnings('Lunch med kund på restaurang')
+    const representation = warnings.find((w) => w.category === 'Representation')
+
+    expect(representation).toBeDefined()
+    expect(representation!.warningLevel).toBe('warning')
+    expect(representation!.message).toBe(
+      'Måltider kan vara avdragsgilla som representation. Inkomstskatteavdraget togs bort 2017, men momsen är avdragsgill på upp till 300 kr/person (exkl. moms) enligt ML 13 kap 24-25 §§.'
+    )
+    expect(representation!.legalBasis).toBe('IL 16 kap 2 §, ML 13 kap 24-25 §§')
+  })
+
+  it('never claims the VAT deduction was abolished and never cites the repealed ML 1994:200 chapter', () => {
+    const warnings = checkExpenseWarnings('Middag på restaurang')
+    const representation = warnings.find((w) => w.category === 'Representation')
+
+    expect(representation).toBeDefined()
+    // The pre-fix text said 'Momsen är inte avdragsgill sedan 2017', which is
+    // legally inverted: Prop. 2016/17:1 abolished the income-tax deduction but
+    // retained the VAT deduction (now ML 2023:200, 13 kap 24-25 §§).
+    expect(representation!.message).not.toMatch(/momsen är inte avdragsgill/i)
+    expect(representation!.legalBasis).not.toMatch(/ML 8:9/)
+  })
+
+  it('triggers on restaurant, lunch, dinner, and fika descriptions', () => {
+    for (const description of ['Restaurang Prinsen', 'lunch', 'middag', 'fika med teamet']) {
+      const warnings = checkExpenseWarnings(description)
+      expect(warnings.some((w) => w.category === 'Representation')).toBe(true)
+    }
+  })
+
+  it('does not trigger the representation warning for unrelated descriptions', () => {
+    const warnings = checkExpenseWarnings('Adobe software subscription')
+    expect(warnings.some((w) => w.category === 'Representation')).toBe(false)
+  })
+})

lib/tax/expense-warnings.ts

@@ -54,8 +54,8 @@ const warningPatterns: {
     warning: {
       category: 'Representation',
       warningLevel: 'warning',
-      message: 'Måltider kan vara avdragsgilla som representation med max 300 kr per person (exkl. moms). Momsen är inte avdragsgill sedan 2017.',
-      legalBasis: 'IL 16 kap 2§, ML 8:9',
+      message: 'Måltider kan vara avdragsgilla som representation. Inkomstskatteavdraget togs bort 2017, men momsen är avdragsgill på upp till 300 kr/person (exkl. moms) enligt ML 13 kap 24-25 §§.',
+      legalBasis: 'IL 16 kap 2 §, ML 13 kap 24-25 §§',
     },
   },
   {