diff --git a/app/(dashboard)/reports/page.tsx b/app/(dashboard)/reports/page.tsx
index 1d679972..cd8438a8 100644
--- a/app/(dashboard)/reports/page.tsx
+++ b/app/(dashboard)/reports/page.tsx
@@ -1243,7 +1243,7 @@ function VatDeclarationView() {
                 {/* Utgående moms */}
                 <div>
                   <h4 className="font-semibold mb-3">Utgående moms (försäljning)</h4>
-                  <div className="overflow-x-auto -mx-2 px-2"><table className="w-full text-sm min-w-[400px]">
+                  <div><table className="w-full text-sm">
                     <tbody>
                       {data.rutor.ruta05 > 0 && (
                         <tr className="border-b">
@@ -1305,7 +1305,7 @@ function VatDeclarationView() {
                     data.rutor.ruta30 > 0 || data.rutor.ruta31 > 0 || data.rutor.ruta32 > 0) && (
                     <>
                       <h4 className="font-semibold mb-3 mt-6">Omvänd skattskyldighet (inköp)</h4>
-                      <div className="overflow-x-auto -mx-2 px-2"><table className="w-full text-sm min-w-[400px]">
+                      <div><table className="w-full text-sm">
                         <tbody>
                           <VatRutaRow ruta="20" label="Inköp av varor från annat EU-land" amount={0} baseAmount={data.rutor.ruta20} noVat />
                           <VatRutaRow ruta="21" label="Inköp av tjänster från annat EU-land" amount={0} baseAmount={data.rutor.ruta21} noVat />
@@ -1324,7 +1324,7 @@ function VatDeclarationView() {
                 {/* Ingående moms */}
                 <div>
                   <h4 className="font-semibold mb-3">Ingående moms (avdragsgill)</h4>
-                  <div className="overflow-x-auto -mx-2 px-2"><table className="w-full text-sm min-w-[400px]">
+                  <div><table className="w-full text-sm">
                     <tbody>
                       <tr className="border-b">
                         <td className="py-2">
diff --git a/components/reports/SkatteverketPanel.tsx b/components/reports/SkatteverketPanel.tsx
index f948ae75..df26116e 100644
--- a/components/reports/SkatteverketPanel.tsx
+++ b/components/reports/SkatteverketPanel.tsx
@@ -36,6 +36,22 @@ interface SkatteverketStatus {
   expiresAt?: string
 }
 
+/**
+ * Codes from /lib/api-client.ts's SkatteverketAuthError that mean "the user
+ * needs to reconnect with BankID before this action can succeed". When the API
+ * returns one of these codes we flip the local status.expired flag so the
+ * "Session utgången" badge + "Förnya session" button surface, even if the
+ * upstream /status endpoint hasn't reflected the change yet.
+ */
+const AUTH_RECONNECT_CODES = new Set([
+  'NOT_CONNECTED',
+  'SESSION_EXPIRED',
+  'REFRESH_EXHAUSTED',
+  'TOKEN_REVOKED',
+  'TOKEN_CORRUPTED',
+  'MISSING_SCOPE',
+])
+
 // Shape per Skatteverket Momsdeklaration v1.0.24 RAML
 // (kontrollResultat.resultat[].{kod, status, beskrivning})
 interface KontrollResult {
@@ -90,6 +106,21 @@ function SkatteverketPanelInner({ periodType, year, period, hasData, rutor }: Sk
   const localErrors = localChecks.filter((c) => c.status === 'ERROR')
   const localBlocked = localErrors.length > 0
 
+  /**
+   * Apply an API JSON error result. When the error indicates the SKV session
+   * has expired/been revoked/lost scope, immediately reflect that in the
+   * local status so the "Förnya session" CTA appears next to the message —
+   * the user shouldn't have to wait for /status to catch up.
+   */
+  const applyApiError = useCallback((result: { error?: string; code?: string } | null) => {
+    if (!result?.error) return false
+    setError(result.error)
+    if (result.code && AUTH_RECONNECT_CODES.has(result.code)) {
+      setStatus((prev) => prev ? { ...prev, expired: true } : prev)
+    }
+    return true
+  }, [])
+
   const fetchStatus = useCallback(async () => {
     try {
       const res = await fetch('/api/extensions/ext/skatteverket/status')
@@ -169,8 +200,8 @@ function SkatteverketPanelInner({ periodType, year, period, hasData, rutor }: Sk
         body: JSON.stringify({ periodType, year, period }),
       })
       const result = await res.json()
-      if (result.error) {
-        setError(result.error)
+      if (applyApiError(result)) {
+        // surfaced + status updated; nothing more to do
       } else {
         const controls: KontrollResult[] = result.data?.kontrollResultat?.resultat || []
         setKontroller(controls)
@@ -215,8 +246,8 @@ function SkatteverketPanelInner({ periodType, year, period, hasData, rutor }: Sk
         body: JSON.stringify({ periodType, year, period }),
       })
       const result = await res.json()
-      if (result.error) {
-        setError(result.error)
+      if (applyApiError(result)) {
+        // surfaced + status updated; nothing more to do
       } else {
         const controls: KontrollResult[] = result.data?.kontrollResultat?.resultat || []
         setKontroller(controls)
@@ -245,8 +276,8 @@ function SkatteverketPanelInner({ periodType, year, period, hasData, rutor }: Sk
         { method: 'PUT' }
       )
       const result = await res.json()
-      if (result.error) {
-        setError(result.error)
+      if (applyApiError(result)) {
+        // surfaced + status updated; nothing more to do
       } else if (result.data?.signeringsLank) {
         setSigneringslank(result.data.signeringsLank)
         setSuccess('Utkastet är låst. Öppna signeringslänken för att signera med BankID.')
@@ -269,8 +300,8 @@ function SkatteverketPanelInner({ periodType, year, period, hasData, rutor }: Sk
         { method: 'DELETE' }
       )
       const result = await res.json()
-      if (result.error) {
-        setError(result.error)
+      if (applyApiError(result)) {
+        // surfaced + status updated; nothing more to do
       } else {
         setSigneringslank(null)
         setSuccess('Utkastet har låsts upp')
@@ -292,8 +323,8 @@ function SkatteverketPanelInner({ periodType, year, period, hasData, rutor }: Sk
         )}&redovisningsperiod=${getRedovisningsperiod()}`
       )
       const result = await res.json()
-      if (result.error) {
-        setError(result.error)
+      if (applyApiError(result)) {
+        // surfaced + status updated; nothing more to do
       } else if (result.data) {
         setSubmitted(result.data)
         setSuccess('Deklarationen har lämnats in')
@@ -323,7 +354,9 @@ function SkatteverketPanelInner({ periodType, year, period, hasData, rutor }: Sk
         setSuccess('Utkastet har raderats från Eget utrymme')
       } else {
         const result = await res.json().catch(() => ({}))
-        setError(result.error || `Kunde inte radera utkast (${res.status})`)
+        if (!applyApiError(result)) {
+          setError(`Kunde inte radera utkast (${res.status})`)
+        }
       }
     } catch {
       setError('Kunde inte radera utkast')
@@ -342,8 +375,8 @@ function SkatteverketPanelInner({ periodType, year, period, hasData, rutor }: Sk
         )}&redovisningsperiod=${getRedovisningsperiod()}`
       )
       const result = await res.json()
-      if (result.error) {
-        setError(result.error)
+      if (applyApiError(result)) {
+        // surfaced + status updated; nothing more to do
       } else if (!result.data) {
         setSuccess('Inget sparat utkast hittades för perioden')
       } else {
@@ -369,8 +402,8 @@ function SkatteverketPanelInner({ periodType, year, period, hasData, rutor }: Sk
         )}&redovisningsperiod=${getRedovisningsperiod()}`
       )
       const result = await res.json()
-      if (result.error) {
-        setError(result.error)
+      if (applyApiError(result)) {
+        // surfaced + status updated; nothing more to do
       } else if (!result.data) {
         setSuccess('Inget beslut hittades för perioden')
       } else {
@@ -455,10 +488,21 @@ function SkatteverketPanelInner({ periodType, year, period, hasData, rutor }: Sk
               Ansluten
             </Badge>
             {status.expired && (
-              <Badge variant="destructive" className="gap-1">
-                <AlertCircle className="h-3 w-3" />
-                Session utgången
-              </Badge>
+              <>
+                <Badge variant="destructive" className="gap-1">
+                  <AlertCircle className="h-3 w-3" />
+                  Session utgången
+                </Badge>
+                <Button
+                  size="sm"
+                  variant="outline"
+                  onClick={handleConnect}
+                  className="gap-1.5 h-7"
+                >
+                  <Link2 className="h-3.5 w-3.5" />
+                  Förnya session
+                </Button>
+              </>
             )}
           </div>
         </div>
diff --git a/components/transactions/JournalEntryPreview.tsx b/components/transactions/JournalEntryPreview.tsx
index 99cd8e53..94ba055b 100644
--- a/components/transactions/JournalEntryPreview.tsx
+++ b/components/transactions/JournalEntryPreview.tsx
@@ -24,6 +24,8 @@ interface JournalEntryPreviewProps {
   templateDebitAccount?: string
   templateCreditAccount?: string
   templateVatRate?: number
+  templateVatTreatment?: VatTreatment | null
+  templateSupplierType?: 'eu_business' | 'non_eu_business' | 'swedish_business'
   /** For multi-line counterparty template bookings */
   linePattern?: LinePatternEntry[]
   settlementAccount?: string
@@ -39,6 +41,8 @@ export default function JournalEntryPreview({
   templateDebitAccount,
   templateCreditAccount,
   templateVatRate,
+  templateVatTreatment,
+  templateSupplierType,
   linePattern,
   settlementAccount = '1930',
 }: JournalEntryPreviewProps) {
@@ -91,6 +95,7 @@ export default function JournalEntryPreview({
       const vatAmt = extractVatAmount(absAmount, vatRate)
       const netAmt = extractNetAmount(absAmount, vatRate)
       const isIncome = amount > 0
+      const isReverseCharge = templateVatTreatment === 'reverse_charge' && !isIncome
 
       if (isIncome) {
         // Income: debit bank gross, credit revenue net, credit output VAT
@@ -101,6 +106,32 @@ export default function JournalEntryPreview({
           const outputVatAccount = vatRate === 0.06 ? '2631' : vatRate === 0.12 ? '2621' : '2611'
           result.push({ side: 'kredit', account: outputVatAccount, amount: vatAmt })
         }
+      } else if (isReverseCharge) {
+        // Expense with reverse charge: full reverse-charge verifikation
+        // (must match engine output in buildMappingResultFromTemplate).
+        const rcRate = 0.25
+        const rcVatAmt = Math.round(absAmount * rcRate * 100) / 100
+        const supplierType = templateSupplierType ?? 'eu_business'
+        const isDomestic = supplierType === 'swedish_business'
+
+        // Expense gross + bank
+        result.push({ side: 'debet', account: templateDebitAccount, amount: absAmount })
+        result.push({ side: 'kredit', account: templateCreditAccount, amount: absAmount })
+
+        // Fiktiv moms pair: 2645 (or 2647 domestic) / 2614
+        result.push({ side: 'debet', account: isDomestic ? '2647' : '2645', amount: rcVatAmt })
+        result.push({ side: 'kredit', account: '2614', amount: rcVatAmt })
+
+        // Basbelopp pair: 44xx|45xx / 4598 — populates rutor 20–24.
+        // Skip if the debit account is already a basis account.
+        if (!/^4[45]\d{2}$/.test(templateDebitAccount)) {
+          const basisAccount =
+            supplierType === 'eu_business' ? '4535'
+            : supplierType === 'non_eu_business' ? '4531'
+            : '4425'
+          result.push({ side: 'debet', account: basisAccount, amount: absAmount })
+          result.push({ side: 'kredit', account: '4598', amount: absAmount })
+        }
       } else {
         // Expense: debit expense net + input VAT, credit bank gross
         result.push({ side: 'debet', account: templateDebitAccount, amount: netAmt })
@@ -150,7 +181,7 @@ export default function JournalEntryPreview({
     }
 
     return result
-  }, [amount, category, vatTreatment, accountOverride, entityType, templateDebitAccount, templateCreditAccount, templateVatRate, linePattern, settlementAccount])
+  }, [amount, category, vatTreatment, accountOverride, entityType, templateDebitAccount, templateCreditAccount, templateVatRate, templateVatTreatment, templateSupplierType, linePattern, settlementAccount])
 
   if (lines.length === 0) return null
 
diff --git a/components/transactions/QuickReviewDialog.tsx b/components/transactions/QuickReviewDialog.tsx
index e6bb0241..032e8ea2 100644
--- a/components/transactions/QuickReviewDialog.tsx
+++ b/components/transactions/QuickReviewDialog.tsx
@@ -172,7 +172,7 @@ export default function QuickReviewDialog({
       }
       onOpenChange(o)
     }}>
-      <DialogContent className="max-w-md max-h-[85vh] overflow-y-auto">
+      <DialogContent className="max-w-md sm:max-w-lg max-h-[85vh] overflow-y-auto">
         <DialogHeader>
           <DialogTitle>Granska bokföring</DialogTitle>
           <DialogDescription>
@@ -264,7 +264,13 @@ export default function QuickReviewDialog({
           {...(isCounterpartyTemplate
             ? { linePattern: counterpartyLinePattern ?? undefined }
             : templateId && template
-              ? { templateDebitAccount: template.debit_account, templateCreditAccount: template.credit_account, templateVatRate: template.vat_rate }
+              ? {
+                  templateDebitAccount: template.debit_account,
+                  templateCreditAccount: template.credit_account,
+                  templateVatRate: template.vat_rate,
+                  templateVatTreatment: template.vat_treatment,
+                  templateSupplierType: template.reverse_charge_supplier_type,
+                }
               : { category, vatTreatment: isLiabilityAccount ? 'none' : vatTreatment, accountOverride, entityType }
           )}
         />
diff --git a/lib/bookkeeping/__tests__/booking-templates.test.ts b/lib/bookkeeping/__tests__/booking-templates.test.ts
index 391be003..e18c8cd3 100644
--- a/lib/bookkeeping/__tests__/booking-templates.test.ts
+++ b/lib/bookkeeping/__tests__/booking-templates.test.ts
@@ -316,18 +316,80 @@ describe('buildMappingResultFromTemplate', () => {
     expect(result.vat_lines[0].debit_amount).toBe(30) // 530 * 0.06 / 1.06 = 30
   })
 
-  it('produces reverse charge lines for EU purchases', () => {
+  it('produces reverse charge lines for EU purchases (fiktiv moms + basbelopp)', () => {
     const template = getTemplate('it_saas_eu')
     const tx = makeTransaction({ amount: -1000 })
     const result = buildMappingResultFromTemplate(template, tx, 'enskild_firma')
 
-    expect(result.vat_lines).toHaveLength(2)
-    // Fiktiv ingående moms
+    // Four lines: fiktiv-moms pair + basbelopp pair. Without the basbelopp
+    // pair the deklaration is rejected with FK004 (ruta 30-32 without 20-24).
+    expect(result.vat_lines).toHaveLength(4)
+    // Fiktiv ingående moms (EU: 2645)
     expect(result.vat_lines[0].account_number).toBe('2645')
     expect(result.vat_lines[0].debit_amount).toBe(250)
-    // Fiktiv utgående moms
+    // Fiktiv utgående moms (25%: 2614)
     expect(result.vat_lines[1].account_number).toBe('2614')
     expect(result.vat_lines[1].credit_amount).toBe(250)
+    // Basbelopp EU services 25% → ruta 21
+    expect(result.vat_lines[2].account_number).toBe('4535')
+    expect(result.vat_lines[2].debit_amount).toBe(1000)
+    // Motkonto basbelopp
+    expect(result.vat_lines[3].account_number).toBe('4598')
+    expect(result.vat_lines[3].credit_amount).toBe(1000)
+  })
+
+  it('defaults to eu_business supplier type when not set on template', () => {
+    // it_cloud_hosting has no explicit reverse_charge_supplier_type
+    const template = getTemplate('it_cloud_hosting')
+    const tx = makeTransaction({ amount: -800 })
+    const result = buildMappingResultFromTemplate(template, tx, 'enskild_firma')
+
+    expect(result.vat_lines).toHaveLength(4)
+    // Defaults to EU services → 4535
+    expect(result.vat_lines[2].account_number).toBe('4535')
+    expect(result.vat_lines[2].debit_amount).toBe(800)
+  })
+
+  it('uses 4531 basbelopp for non-EU supplier type', () => {
+    const template: BookingTemplate = {
+      ...getTemplate('it_cloud_hosting'),
+      reverse_charge_supplier_type: 'non_eu_business',
+    }
+    const tx = makeTransaction({ amount: -1000 })
+    const result = buildMappingResultFromTemplate(template, tx, 'enskild_firma')
+
+    expect(result.vat_lines).toHaveLength(4)
+    expect(result.vat_lines[0].account_number).toBe('2645') // non-EU still uses 2645
+    expect(result.vat_lines[2].account_number).toBe('4531') // non-EU services → ruta 22
+  })
+
+  it('uses 4425 basbelopp and 2647 for domestic (swedish) reverse charge', () => {
+    const template: BookingTemplate = {
+      ...getTemplate('it_cloud_hosting'),
+      reverse_charge_supplier_type: 'swedish_business',
+    }
+    const tx = makeTransaction({ amount: -1000 })
+    const result = buildMappingResultFromTemplate(template, tx, 'enskild_firma')
+
+    expect(result.vat_lines).toHaveLength(4)
+    // Domestic RC uses 2647 (ML 16 kap) for the input pair
+    expect(result.vat_lines[0].account_number).toBe('2647')
+    // Domestic services (byggtjänster) → 4425, ruta 24
+    expect(result.vat_lines[2].account_number).toBe('4425')
+  })
+
+  it('skips basbelopp emission when template already debits a basis account', () => {
+    const template: BookingTemplate = {
+      ...getTemplate('it_cloud_hosting'),
+      debit_account: '4535', // user-customized template that books directly to basis
+    }
+    const tx = makeTransaction({ amount: -1000 })
+    const result = buildMappingResultFromTemplate(template, tx, 'enskild_firma')
+
+    // Only the fiktiv-moms pair — basbelopp would double-count.
+    expect(result.vat_lines).toHaveLength(2)
+    expect(result.vat_lines[0].account_number).toBe('2645')
+    expect(result.vat_lines[1].account_number).toBe('2614')
   })
 
   it('produces no VAT lines for exempt expenses', () => {
diff --git a/lib/bookkeeping/__tests__/mapping-engine.test.ts b/lib/bookkeeping/__tests__/mapping-engine.test.ts
index 1e6863e1..bf992172 100644
--- a/lib/bookkeeping/__tests__/mapping-engine.test.ts
+++ b/lib/bookkeeping/__tests__/mapping-engine.test.ts
@@ -341,5 +341,114 @@ describe('mapping-engine', () => {
       expect(result.credit_account).toBe('1930')
       expect(result.confidence).toBe(0.95)
     })
+
+    it('emits both fiktiv-moms and basbelopp lines for reverse_charge rules', async () => {
+      const { evaluateMappingRules } = await import('../mapping-engine')
+
+      const tx = makeTransaction({
+        amount: -1000,
+        merchant_name: 'AWS',
+        description: 'AWS EU-WEST-1',
+      })
+
+      mockResult({
+        data: [
+          {
+            id: 'rule-rc',
+            user_id: 'user-1',
+            rule_name: 'AWS reverse charge',
+            rule_type: 'merchant_name',
+            priority: 10,
+            mcc_codes: null,
+            merchant_pattern: 'AWS',
+            description_pattern: null,
+            amount_min: null,
+            amount_max: null,
+            debit_account: '5421',
+            credit_account: '1930',
+            vat_treatment: 'reverse_charge',
+            vat_debit_account: null,
+            vat_credit_account: null,
+            risk_level: 'LOW',
+            default_private: false,
+            requires_review: false,
+            confidence_score: 0.9,
+            capitalization_threshold: null,
+            capitalized_debit_account: null,
+            is_active: true,
+            source: 'system',
+            user_description: null,
+            template_id: null,
+            created_at: '2024-01-01',
+            updated_at: '2024-01-01',
+          },
+        ],
+        error: null,
+      })
+
+      const result = await evaluateMappingRules(mockSupabase as never, 'user-1', tx)
+
+      // Fiktiv-moms pair + basbelopp pair = 4 lines (FK004 guard)
+      expect(result.vat_lines).toHaveLength(4)
+      expect(result.vat_lines[0].account_number).toBe('2645')
+      expect(result.vat_lines[0].debit_amount).toBe(250)
+      expect(result.vat_lines[1].account_number).toBe('2614')
+      expect(result.vat_lines[1].credit_amount).toBe(250)
+      expect(result.vat_lines[2].account_number).toBe('4535')
+      expect(result.vat_lines[2].debit_amount).toBe(1000)
+      expect(result.vat_lines[3].account_number).toBe('4598')
+      expect(result.vat_lines[3].credit_amount).toBe(1000)
+    })
+
+    it('skips basbelopp emission when rule already debits a basis account', async () => {
+      const { evaluateMappingRules } = await import('../mapping-engine')
+
+      const tx = makeTransaction({
+        amount: -1000,
+        merchant_name: 'AWS',
+      })
+
+      mockResult({
+        data: [
+          {
+            id: 'rule-rc-basis',
+            user_id: 'user-1',
+            rule_name: 'AWS RC to basis',
+            rule_type: 'merchant_name',
+            priority: 10,
+            mcc_codes: null,
+            merchant_pattern: 'AWS',
+            description_pattern: null,
+            amount_min: null,
+            amount_max: null,
+            debit_account: '4535',
+            credit_account: '1930',
+            vat_treatment: 'reverse_charge',
+            vat_debit_account: null,
+            vat_credit_account: null,
+            risk_level: 'LOW',
+            default_private: false,
+            requires_review: false,
+            confidence_score: 0.9,
+            capitalization_threshold: null,
+            capitalized_debit_account: null,
+            is_active: true,
+            source: 'system',
+            user_description: null,
+            template_id: null,
+            created_at: '2024-01-01',
+            updated_at: '2024-01-01',
+          },
+        ],
+        error: null,
+      })
+
+      const result = await evaluateMappingRules(mockSupabase as never, 'user-1', tx)
+
+      // Only fiktiv-moms pair — basbelopp already covered by the expense line
+      expect(result.vat_lines).toHaveLength(2)
+      expect(result.vat_lines[0].account_number).toBe('2645')
+      expect(result.vat_lines[1].account_number).toBe('2614')
+    })
   })
 })
diff --git a/lib/bookkeeping/booking-templates.ts b/lib/bookkeeping/booking-templates.ts
index fbf94b62..0f5c881d 100644
--- a/lib/bookkeeping/booking-templates.ts
+++ b/lib/bookkeeping/booking-templates.ts
@@ -7,7 +7,12 @@ import type {
   VatTreatment,
   RiskLevel,
 } from '@/types'
-import { getVatRate, generateReverseChargeLines, generateInputVatLine } from './vat-entries'
+import {
+  getVatRate,
+  generateReverseChargeLines,
+  generateReverseChargeBasisLines,
+  generateInputVatLine,
+} from './vat-entries'
 
 // ============================================================
 // Types
@@ -59,6 +64,13 @@ export interface BookingTemplate {
   description_sv: string
   common: boolean
   requires_vat_registration_data?: boolean
+  /**
+   * Supplier-type hint for reverse-charge bookings. Determines which 44xx/45xx
+   * basbelopp account is emitted alongside the 2645/2614 fiktiv-moms pair so
+   * Skatteverket's momsdeklaration rutor 20–24 line up with rutor 30–32
+   * (felkod FK004 if absent). Default 'eu_business' when unset.
+   */
+  reverse_charge_supplier_type?: 'eu_business' | 'non_eu_business' | 'swedish_business'
 }
 
 export interface TemplateGroupInfo {
@@ -1536,6 +1548,15 @@ export function findMatchingTemplates(
     .slice(0, 10)
 }
 
+/**
+ * Whether an account number sits in the reverse-charge basbelopp range
+ * (44xx/45xx series — ruta 20–24 inputs). Used to skip redundant basis
+ * emission when the template already books to such an account.
+ */
+function isBasisAccount(account: string): boolean {
+  return /^4[45]\d{2}$/.test(account)
+}
+
 /**
  * Convert a booking template into a MappingResult.
  * Follows the same pattern as buildMappingResultFromCategory in category-mapping.ts.
@@ -1562,9 +1583,17 @@ export function buildMappingResultFromTemplate(
     const vatRate = getVatRate(template.vat_treatment)
 
     if (template.vat_treatment === 'reverse_charge' && isExpense) {
-      // EU reverse charge: fiktiv moms (offsetting entries)
+      // EU/non-EU/domestic reverse charge: emit BOTH the fiktiv-moms pair
+      // (2645|2647 / 2614) AND the basbelopp pair (44xx|45xx / 4598). The
+      // basbelopp pair populates momsdeklaration rutor 20–24; without it
+      // Skatteverket rejects with FK004 ("ruta 30-32 utan motsvarande
+      // basbelopp i 20-24" — ML 13 kap kräver båda sidor).
       const absAmount = Math.abs(transaction.amount)
-      const rcLines = generateReverseChargeLines(absAmount)
+      const supplierType = template.reverse_charge_supplier_type ?? 'eu_business'
+      const isDomestic = supplierType === 'swedish_business'
+      const rcRate = 0.25 // fiktiv moms rate; current templates are 25%
+
+      const rcLines = generateReverseChargeLines(absAmount, rcRate, isDomestic)
       for (const rcl of rcLines) {
         vatLines.push({
           account_number: rcl.account_number,
@@ -1573,6 +1602,20 @@ export function buildMappingResultFromTemplate(
           description: rcl.line_description || '',
         })
       }
+
+      // Skip basbelopp emission if the template already books the expense
+      // directly to a basis account (44xx/45xx series) — would double-count.
+      if (!isBasisAccount(debitAccount)) {
+        const basisLines = generateReverseChargeBasisLines(absAmount, rcRate, supplierType)
+        for (const bl of basisLines) {
+          vatLines.push({
+            account_number: bl.account_number,
+            debit_amount: bl.debit_amount,
+            credit_amount: bl.credit_amount,
+            description: bl.line_description || '',
+          })
+        }
+      }
     } else if (vatRate > 0 && isExpense) {
       // Input VAT deduction
       const absAmount = Math.abs(transaction.amount)
diff --git a/lib/bookkeeping/mapping-engine.ts b/lib/bookkeeping/mapping-engine.ts
index 3d4860a2..270499a8 100644
--- a/lib/bookkeeping/mapping-engine.ts
+++ b/lib/bookkeeping/mapping-engine.ts
@@ -2,6 +2,7 @@ import type { SupabaseClient } from '@supabase/supabase-js'
 import {
   generateInputVatLine,
   generateReverseChargeLines,
+  generateReverseChargeBasisLines,
 } from './vat-entries'
 import { findMatchingTemplates, buildMappingResultFromTemplate } from './booking-templates'
 import {
@@ -221,8 +222,13 @@ function buildResult(rule: MappingRule, transaction: Transaction, entityType?: E
   const vatLines: VatJournalLine[] = []
   if (isExpense && !rule.default_private && rule.vat_treatment) {
     if (rule.vat_treatment === 'reverse_charge') {
-      // EU reverse charge: fiktiv moms (offsetting entries)
-      const rcLines = generateReverseChargeLines(absAmount)
+      // Reverse charge: emit BOTH the fiktiv-moms pair (2645/2614) AND the
+      // basbelopp pair (44xx|45xx / 4598). The basbelopp pair populates
+      // momsdeklaration rutor 20–24; without it Skatteverket rejects with
+      // FK004. Mapping rules don't carry supplier-country today, so we
+      // default to EU services — the most common reverse-charge scenario.
+      const rcRate = 0.25
+      const rcLines = generateReverseChargeLines(absAmount, rcRate, false)
       for (const rcl of rcLines) {
         vatLines.push({
           account_number: rcl.account_number,
@@ -231,6 +237,19 @@ function buildResult(rule: MappingRule, transaction: Transaction, entityType?: E
           description: rcl.line_description || '',
         })
       }
+
+      // Skip basbelopp emission if the rule already books to a basis account.
+      if (!/^4[45]\d{2}$/.test(debitAccount)) {
+        const basisLines = generateReverseChargeBasisLines(absAmount, rcRate, 'eu_business')
+        for (const bl of basisLines) {
+          vatLines.push({
+            account_number: bl.account_number,
+            debit_amount: bl.debit_amount,
+            credit_amount: bl.credit_amount,
+            description: bl.line_description || '',
+          })
+        }
+      }
     } else if (rule.vat_treatment === 'standard_25' || rule.vat_treatment === 'reduced_12' || rule.vat_treatment === 'reduced_6') {
       const vatRate =
         rule.vat_treatment === 'standard_25' ? 0.25
diff --git a/lib/reports/__tests__/vat-declaration-checks.test.ts b/lib/reports/__tests__/vat-declaration-checks.test.ts
index 96649d1f..43e05a51 100644
--- a/lib/reports/__tests__/vat-declaration-checks.test.ts
+++ b/lib/reports/__tests__/vat-declaration-checks.test.ts
@@ -101,4 +101,107 @@ describe('runVatDeclarationChecks', () => {
     const findings = runVatDeclarationChecks(rutor)
     expect(findings.find((f) => f.code === 'SUMMA_MOMS_DRIFT')).toBeUndefined()
   })
+
+  // SKV §4.1.1.4 rule 1 — taxable sales base without output VAT.
+  it('flags ERROR when taxable sales (ruta 05) booked without output VAT', () => {
+    const rutor: VatDeclarationRutor = {
+      ...emptyRutor,
+      ruta05: 10000,
+      // ruta 10/11/12 all zero — SKV rule 1 violation
+      ruta49: 0,
+    }
+    const findings = runVatDeclarationChecks(rutor)
+    const finding = findings.find((f) => f.code === 'TAXABLE_SALES_WITHOUT_OUTPUT')
+    expect(finding?.status).toBe('ERROR')
+    expect(finding?.message).toMatch(/försäljning/)
+    expect(finding?.message).toMatch(/utgående moms/)
+  })
+
+  it('flags ERROR for ruta 06 (uttag) without output VAT', () => {
+    const rutor: VatDeclarationRutor = {
+      ...emptyRutor,
+      ruta06: 5000,
+      ruta49: 0,
+    }
+    const findings = runVatDeclarationChecks(rutor)
+    expect(findings.find((f) => f.code === 'TAXABLE_SALES_WITHOUT_OUTPUT')?.status).toBe('ERROR')
+  })
+
+  it('does not flag taxable sales without output VAT when output VAT is present', () => {
+    const rutor: VatDeclarationRutor = {
+      ...emptyRutor,
+      ruta05: 10000,
+      ruta10: 2500,
+      ruta49: 2500,
+    }
+    const findings = runVatDeclarationChecks(rutor)
+    expect(findings.find((f) => f.code === 'TAXABLE_SALES_WITHOUT_OUTPUT')).toBeUndefined()
+  })
+
+  // Mirror: output VAT without taxable sales base.
+  it('flags ERROR when output VAT booked without taxable sales base', () => {
+    const rutor: VatDeclarationRutor = {
+      ...emptyRutor,
+      // No ruta 05/06/07/08
+      ruta10: 2500,
+      ruta49: 2500,
+    }
+    const findings = runVatDeclarationChecks(rutor)
+    expect(findings.find((f) => f.code === 'OUTPUT_VAT_WITHOUT_SALES_BASE')?.status).toBe('ERROR')
+  })
+
+  // SKV §4.1.1.4 rule 5 — import base without import output VAT.
+  it('flags ERROR when import base (ruta 50) without import output VAT', () => {
+    const rutor: VatDeclarationRutor = {
+      ...emptyRutor,
+      ruta50: 10000,
+      // ruta 60/61/62 all zero
+      ruta48: 0,
+      ruta49: 0,
+    }
+    const findings = runVatDeclarationChecks(rutor)
+    expect(findings.find((f) => f.code === 'IMPORT_BASE_WITHOUT_OUTPUT')?.status).toBe('ERROR')
+  })
+
+  // SKV §4.1.1.4 rule 6 — import output VAT without import base.
+  it('flags ERROR when import output VAT (ruta 60) without ruta 50', () => {
+    const rutor: VatDeclarationRutor = {
+      ...emptyRutor,
+      ruta60: 2500,
+      ruta48: 2500,
+      ruta49: 0,
+    }
+    const findings = runVatDeclarationChecks(rutor)
+    expect(findings.find((f) => f.code === 'IMPORT_OUTPUT_WITHOUT_BASE')?.status).toBe('ERROR')
+  })
+
+  it('does not flag import checks when both base and output VAT are present', () => {
+    const rutor: VatDeclarationRutor = {
+      ...emptyRutor,
+      ruta50: 10000,
+      ruta60: 2500,
+      ruta48: 2500,
+      ruta49: 0,
+    }
+    const findings = runVatDeclarationChecks(rutor)
+    expect(findings.find((f) => f.code === 'IMPORT_BASE_WITHOUT_OUTPUT')).toBeUndefined()
+    expect(findings.find((f) => f.code === 'IMPORT_OUTPUT_WITHOUT_BASE')).toBeUndefined()
+  })
+
+  // Multiple findings should surface together so the user sees the whole picture.
+  it('reports multiple distinct findings for a deeply broken declaration', () => {
+    const rutor: VatDeclarationRutor = {
+      ...emptyRutor,
+      ruta05: 10000,    // taxable sales but no output VAT
+      ruta30: 2500,     // RC output but no RC basis
+      ruta50: 5000,     // import base but no import output
+      ruta48: 0,
+      ruta49: 2500,
+    }
+    const findings = runVatDeclarationChecks(rutor)
+    const codes = findings.map((f) => f.code).sort()
+    expect(codes).toContain('TAXABLE_SALES_WITHOUT_OUTPUT')
+    expect(codes).toContain('RC_BASIS_MISSING')
+    expect(codes).toContain('IMPORT_BASE_WITHOUT_OUTPUT')
+  })
 })
diff --git a/lib/reports/vat-declaration-checks.ts b/lib/reports/vat-declaration-checks.ts
index b0829d6d..afb4b8fd 100644
--- a/lib/reports/vat-declaration-checks.ts
+++ b/lib/reports/vat-declaration-checks.ts
@@ -43,6 +43,10 @@ export interface VatDeclarationCheck {
     | 'RC_OUTPUT_MISSING'
     | 'RC_INPUT_VAT_MISMATCH'
     | 'SUMMA_MOMS_DRIFT'
+    | 'TAXABLE_SALES_WITHOUT_OUTPUT'
+    | 'IMPORT_BASE_WITHOUT_OUTPUT'
+    | 'IMPORT_OUTPUT_WITHOUT_BASE'
+    | 'OUTPUT_VAT_WITHOUT_SALES_BASE'
   status: VatDeclarationCheckStatus
   /** Swedish user-facing message; safe to render directly in the UI. */
   message: string
@@ -116,6 +120,71 @@ export function runVatDeclarationChecks(rutor: VatDeclarationRutor): VatDeclarat
     })
   }
 
+  // SKV §4.1.1.4 rule 1 — taxable sales base requires output VAT.
+  // If user has booked revenue (3001-3003, uttag, VMB, frivillig uthyrning)
+  // without any output VAT (2611-2638), the declaration will be rejected.
+  // Common cause: revenue posted but VAT line forgotten, or revenue on a
+  // zero-rated account that should have been ruta 35/36/39/40.
+  const taxableSalesBase = rutor.ruta05 + rutor.ruta06 + rutor.ruta07 + rutor.ruta08
+  const taxableSalesOutput = rutor.ruta10 + rutor.ruta11 + rutor.ruta12
+  if (taxableSalesBase > eps && taxableSalesOutput <= eps) {
+    findings.push({
+      code: 'TAXABLE_SALES_WITHOUT_OUTPUT',
+      status: 'ERROR',
+      message:
+        'Du har redovisat momspliktig försäljning (ruta 05-08) men ingen ' +
+        'utgående moms (ruta 10-12). Skatteverket kräver att momspliktig ' +
+        'försäljning kombineras med utgående moms. Kontrollera att VAT-rader ' +
+        'är bokförda på 2611/2621/2631 — eller flytta intäkterna till rätt ' +
+        'momsfri ruta (35/36/39/40) om de inte är momspliktiga.',
+      rutor: ['ruta05', 'ruta06', 'ruta07', 'ruta08', 'ruta10', 'ruta11', 'ruta12'],
+    })
+  }
+
+  // Mirror — output VAT without taxable sales base. Output VAT booked
+  // standalone (e.g. manual correction without matching revenue posting)
+  // would also fail SKV's contract.
+  if (taxableSalesOutput > eps && taxableSalesBase <= eps) {
+    findings.push({
+      code: 'OUTPUT_VAT_WITHOUT_SALES_BASE',
+      status: 'ERROR',
+      message:
+        'Du har redovisat utgående moms (ruta 10-12) men ingen momspliktig ' +
+        'försäljning (ruta 05-08). Skatteverket kräver att utgående moms ' +
+        'matchas med ett försäljningsunderlag. Kontrollera att intäktskonton ' +
+        '(3001/3002/3003) är bokförda för varje VAT-rad.',
+      rutor: ['ruta05', 'ruta06', 'ruta07', 'ruta08', 'ruta10', 'ruta11', 'ruta12'],
+    })
+  }
+
+  // SKV §4.1.1.4 rule 5 — import base requires import output VAT.
+  const importOutput = rutor.ruta60 + rutor.ruta61 + rutor.ruta62
+  if (rutor.ruta50 > eps && importOutput <= eps) {
+    findings.push({
+      code: 'IMPORT_BASE_WITHOUT_OUTPUT',
+      status: 'ERROR',
+      message:
+        'Du har redovisat importunderlag (ruta 50) men ingen utgående ' +
+        'importmoms (ruta 60-62). Skatteverket kräver båda. Kontrollera ' +
+        'att importmoms är bokförd på 2615/2625/2635.',
+      rutor: ['ruta50', 'ruta60', 'ruta61', 'ruta62'],
+    })
+  }
+
+  // SKV §4.1.1.4 rule 6 — import output VAT requires import base.
+  // This was the canary that the Phase 1b ruta50 wiring fixed.
+  if (importOutput > eps && rutor.ruta50 <= eps) {
+    findings.push({
+      code: 'IMPORT_OUTPUT_WITHOUT_BASE',
+      status: 'ERROR',
+      message:
+        'Du har redovisat utgående importmoms (ruta 60-62) men inget ' +
+        'importunderlag (ruta 50). Skatteverket kräver att importmoms ' +
+        'kombineras med tullvärdesunderlag på 4545/4546/4547.',
+      rutor: ['ruta50', 'ruta60', 'ruta61', 'ruta62'],
+    })
+  }
+
   // SummaMoms drift — sanity check that our local ruta49 matches what the
   // mapper will send. If this fires, the calculator and mapper disagree
   // and we'd hit SKV's FK009.
diff --git a/lib/reports/vat-declaration.ts b/lib/reports/vat-declaration.ts
index 12a90a1e..c9a17a65 100644
--- a/lib/reports/vat-declaration.ts
+++ b/lib/reports/vat-declaration.ts
@@ -47,7 +47,7 @@ import type {
  *   4425/4426/4427 (domestic services reverse charge) → ruta 24
  *   4545/4546/4547 (import) → ruta 50
  */
-const ACCOUNT_RUTA: Record<string, { box: keyof VatDeclarationRutor; side: 'credit' | 'debit' }> = {
+export const ACCOUNT_RUTA: Record<string, { box: keyof VatDeclarationRutor; side: 'credit' | 'debit' }> = {
   // Output VAT 25% → ruta 10
   '2610': { box: 'ruta10', side: 'credit' },  // Utgående moms 25% (summary/parent)
   '2611': { box: 'ruta10', side: 'credit' },  // Försäljning inom Sverige
diff --git a/lib/vat/__tests__/moms-box-mapping.test.ts b/lib/vat/__tests__/moms-box-mapping.test.ts
new file mode 100644
index 00000000..db7472b1
--- /dev/null
+++ b/lib/vat/__tests__/moms-box-mapping.test.ts
@@ -0,0 +1,155 @@
+import { describe, it, expect } from 'vitest'
+import {
+  ACCOUNT_TO_BOX,
+  BOX_LABELS,
+  getBoxForAccount,
+  getBoxLabel,
+  type MomsBox,
+} from '../moms-box-mapping'
+import { ACCOUNT_RUTA } from '@/lib/reports/vat-declaration'
+
+describe('ACCOUNT_TO_BOX', () => {
+  it('has a label for every box ID used in the map', () => {
+    const usedBoxes = new Set(Object.values(ACCOUNT_TO_BOX))
+    for (const box of usedBoxes) {
+      expect(BOX_LABELS[box]).toBeTruthy()
+    }
+  })
+
+  it('maps all known revenue accounts to a sales box', () => {
+    expect(ACCOUNT_TO_BOX['3001']).toBe('05')
+    expect(ACCOUNT_TO_BOX['3002']).toBe('05')
+    expect(ACCOUNT_TO_BOX['3003']).toBe('05')
+    expect(ACCOUNT_TO_BOX['3108']).toBe('35')
+    expect(ACCOUNT_TO_BOX['3308']).toBe('39')
+    expect(ACCOUNT_TO_BOX['3105']).toBe('36')
+    expect(ACCOUNT_TO_BOX['3305']).toBe('40')
+  })
+
+  it('maps all output VAT accounts including parent/summary and vilande', () => {
+    expect(ACCOUNT_TO_BOX['2610']).toBe('10')
+    expect(ACCOUNT_TO_BOX['2611']).toBe('10')
+    expect(ACCOUNT_TO_BOX['2618']).toBe('10')
+    expect(ACCOUNT_TO_BOX['2620']).toBe('11')
+    expect(ACCOUNT_TO_BOX['2630']).toBe('12')
+    expect(ACCOUNT_TO_BOX['2614']).toBe('30')
+    expect(ACCOUNT_TO_BOX['2624']).toBe('31')
+    expect(ACCOUNT_TO_BOX['2634']).toBe('32')
+  })
+
+  it('maps all input VAT accounts including parent and domestic RC', () => {
+    expect(ACCOUNT_TO_BOX['2640']).toBe('48')
+    expect(ACCOUNT_TO_BOX['2641']).toBe('48')
+    expect(ACCOUNT_TO_BOX['2645']).toBe('48')
+    expect(ACCOUNT_TO_BOX['2647']).toBe('48')
+    expect(ACCOUNT_TO_BOX['2649']).toBe('48')
+  })
+
+  it('maps reverse-charge basis accounts to the correct ruta', () => {
+    // EU goods → ruta 20
+    expect(ACCOUNT_TO_BOX['4515']).toBe('20')
+    expect(ACCOUNT_TO_BOX['4516']).toBe('20')
+    expect(ACCOUNT_TO_BOX['4517']).toBe('20')
+    // EU services → ruta 21
+    expect(ACCOUNT_TO_BOX['4535']).toBe('21')
+    expect(ACCOUNT_TO_BOX['4536']).toBe('21')
+    expect(ACCOUNT_TO_BOX['4537']).toBe('21')
+    // Non-EU services → ruta 22
+    expect(ACCOUNT_TO_BOX['4531']).toBe('22')
+    expect(ACCOUNT_TO_BOX['4532']).toBe('22')
+    expect(ACCOUNT_TO_BOX['4533']).toBe('22')
+    // Domestic goods RC → ruta 23
+    expect(ACCOUNT_TO_BOX['4415']).toBe('23')
+    expect(ACCOUNT_TO_BOX['4416']).toBe('23')
+    expect(ACCOUNT_TO_BOX['4417']).toBe('23')
+    // Domestic services RC → ruta 24
+    expect(ACCOUNT_TO_BOX['4425']).toBe('24')
+    expect(ACCOUNT_TO_BOX['4426']).toBe('24')
+    expect(ACCOUNT_TO_BOX['4427']).toBe('24')
+  })
+
+  it('maps import beskattningsunderlag accounts to ruta 50', () => {
+    expect(ACCOUNT_TO_BOX['4545']).toBe('50')
+    expect(ACCOUNT_TO_BOX['4546']).toBe('50')
+    expect(ACCOUNT_TO_BOX['4547']).toBe('50')
+  })
+
+  it('maps import output VAT accounts to ruta 60/61/62', () => {
+    expect(ACCOUNT_TO_BOX['2615']).toBe('60')
+    expect(ACCOUNT_TO_BOX['2625']).toBe('61')
+    expect(ACCOUNT_TO_BOX['2635']).toBe('62')
+  })
+
+  it('maps momspliktiga uttag accounts to ruta 06', () => {
+    expect(ACCOUNT_TO_BOX['3401']).toBe('06')
+    expect(ACCOUNT_TO_BOX['3402']).toBe('06')
+    expect(ACCOUNT_TO_BOX['3403']).toBe('06')
+  })
+})
+
+describe('getBoxForAccount', () => {
+  it('returns the box for known accounts', () => {
+    expect(getBoxForAccount('2611')).toBe('10')
+    expect(getBoxForAccount('4535')).toBe('21')
+  })
+
+  it('returns undefined for unknown accounts', () => {
+    expect(getBoxForAccount('9999')).toBeUndefined()
+    expect(getBoxForAccount('1930')).toBeUndefined() // bank account, not VAT-related
+  })
+})
+
+describe('getBoxLabel', () => {
+  it('returns Swedish labels for every box', () => {
+    expect(getBoxLabel('10')).toMatch(/Utgående moms 25%/)
+    expect(getBoxLabel('30')).toMatch(/inköp 25%/)
+    expect(getBoxLabel('48')).toMatch(/Ingående moms/)
+    expect(getBoxLabel('49')).toMatch(/Moms att betala/)
+  })
+})
+
+// Regression guard: ACCOUNT_TO_BOX must stay aligned with the source-of-truth
+// mapping in vat-declaration.ts. If a new account is added to one map without
+// the other, the calculation and the cross-validation labels drift apart.
+describe('ACCOUNT_TO_BOX ↔ ACCOUNT_RUTA alignment', () => {
+  const RUTA_TO_BOX: Record<string, MomsBox> = {
+    ruta05: '05', ruta06: '06', ruta07: '07', ruta08: '08',
+    ruta10: '10', ruta11: '11', ruta12: '12',
+    ruta20: '20', ruta21: '21', ruta22: '22', ruta23: '23', ruta24: '24',
+    ruta30: '30', ruta31: '31', ruta32: '32',
+    ruta35: '35', ruta36: '36', ruta37: '37', ruta38: '38',
+    ruta39: '39', ruta40: '40', ruta41: '41', ruta42: '42',
+    ruta48: '48', ruta49: '49',
+    ruta50: '50', ruta60: '60', ruta61: '61', ruta62: '62',
+  }
+
+  it('every account in ACCOUNT_RUTA exists in ACCOUNT_TO_BOX with the matching box', () => {
+    const drift: string[] = []
+    for (const [account, mapping] of Object.entries(ACCOUNT_RUTA)) {
+      const expectedBox = RUTA_TO_BOX[mapping.box]
+      const actualBox = ACCOUNT_TO_BOX[account]
+      if (!actualBox) {
+        drift.push(`missing in ACCOUNT_TO_BOX: ${account} (should be box ${expectedBox})`)
+      } else if (actualBox !== expectedBox) {
+        drift.push(`mismatched box for ${account}: ACCOUNT_TO_BOX=${actualBox}, ACCOUNT_RUTA=${expectedBox}`)
+      }
+    }
+    expect(drift).toEqual([])
+  })
+
+  it('every account in ACCOUNT_TO_BOX exists in ACCOUNT_RUTA (or is an extra cross-validation hint)', () => {
+    // Allowed extras: accounts in ACCOUNT_TO_BOX that don't feed the declaration
+    // but are useful for the Export VAT Monitor / EU Sales List. Currently these
+    // are the frakter accounts that follow goods treatment.
+    const allowedExtras = new Set<string>(['3521', '3522', '3109'])
+
+    const drift: string[] = []
+    for (const account of Object.keys(ACCOUNT_TO_BOX)) {
+      if (allowedExtras.has(account)) continue
+      if (!ACCOUNT_RUTA[account]) {
+        drift.push(`extra in ACCOUNT_TO_BOX: ${account} (not in ACCOUNT_RUTA — consider adding to declaration mapping or to allowedExtras)`)
+      }
+    }
+    expect(drift).toEqual([])
+  })
+})
diff --git a/lib/vat/moms-box-mapping.ts b/lib/vat/moms-box-mapping.ts
index c031d8cd..5d092b19 100644
--- a/lib/vat/moms-box-mapping.ts
+++ b/lib/vat/moms-box-mapping.ts
@@ -42,13 +42,28 @@ export type MomsBox =
   | '61'  // Importmoms 12%
   | '62'  // Importmoms 6%
 
-/** Map BAS account to momsdeklaration box */
+/**
+ * Map BAS account to momsdeklaration box.
+ *
+ * Source of truth for "which moms box does this BAS account contribute to?"
+ * Used for cross-validation (Export VAT Monitor, EU Sales List) and any
+ * UI that needs to label a journal line by its declaration ruta.
+ *
+ * Must stay aligned with `ACCOUNT_RUTA` in `lib/reports/vat-declaration.ts`
+ * — a regression test asserts that every account mapped here points at the
+ * matching ruta and vice versa.
+ */
 export const ACCOUNT_TO_BOX: Record<string, MomsBox> = {
   // Domestic revenue (taxable) → Box 05
   '3001': '05',  // Försäljning varor/tjänster 25%
   '3002': '05',  // Försäljning varor/tjänster 12%
   '3003': '05',  // Försäljning varor/tjänster 6%
 
+  // Momspliktiga uttag → Box 06
+  '3401': '06',
+  '3402': '06',
+  '3403': '06',
+
   // EU goods (reverse charge, VAT-free) → Box 35
   '3108': '35',  // Försäljning varor till annat EU-land
   '3521': '35',  // Fakturerade frakter EU (follows goods treatment)
@@ -69,22 +84,31 @@ export const ACCOUNT_TO_BOX: Record<string, MomsBox> = {
   // VAT-exempt sales → Box 42
   '3004': '42',  // Momsfri försäljning (AB)
   '3100': '42',  // Momsfria intäkter (EF)
+  '3404': '42',  // Momsfria uttag
+  '3980': '42',  // Erhållna offentliga stöd m.m.
+  '3994': '42',  // Övriga rörelseintäkter momsfria
 
   // Output VAT 25% → Box 10
+  '2610': '10',  // Utgående moms 25% (summary/parent)
   '2611': '10',  // Försäljning inom Sverige
   '2612': '10',  // Egna uttag
   '2613': '10',  // Uthyrning (frivillig skattskyldighet)
   '2616': '10',  // Vinstmarginalbeskattning
+  '2618': '10',  // Vilande utgående moms 25%
   // Output VAT 12% → Box 11
+  '2620': '11',  // Utgående moms 12% (summary/parent)
   '2621': '11',
   '2622': '11',  // Egna uttag
   '2623': '11',  // Uthyrning
   '2626': '11',  // VMB
+  '2628': '11',  // Vilande utgående moms 12%
   // Output VAT 6% → Box 12
+  '2630': '12',  // Utgående moms 6% (summary/parent)
   '2631': '12',
   '2632': '12',  // Egna uttag
   '2633': '12',  // Uthyrning
   '2636': '12',  // VMB
+  '2638': '12',  // Vilande utgående moms 6%
 
   // Reverse charge output VAT → Boxes 30, 31, 32
   '2614': '30',
@@ -97,12 +121,35 @@ export const ACCOUNT_TO_BOX: Record<string, MomsBox> = {
   '2635': '62',  // Import 6%
 
   // Input VAT → Box 48
+  '2640': '48',  // Ingående moms (summary/parent)
   '2641': '48',  // Debiterad ingående moms
   '2642': '48',  // Frivillig skattskyldighet
   '2645': '48',  // Beräknad ingående moms (EU/non-EU förvärv)
   '2646': '48',  // Uthyrning
   '2647': '48',  // Omvänd skattskyldighet i Sverige
   '2649': '48',  // Blandad verksamhet
+
+  // Reverse-charge purchase bases (debit on cost accounts) → Boxes 20-24
+  '4515': '20',  // Inköp varor EU 25%
+  '4516': '20',  // Inköp varor EU 12%
+  '4517': '20',  // Inköp varor EU 6%
+  '4535': '21',  // Inköp tjänster EU 25% (huvudregeln)
+  '4536': '21',  // Inköp tjänster EU 12%
+  '4537': '21',  // Inköp tjänster EU 6%
+  '4531': '22',  // Inköp tjänster utanför EU 25%
+  '4532': '22',  // Inköp tjänster utanför EU 12%
+  '4533': '22',  // Inköp tjänster utanför EU 6%
+  '4415': '23',  // Inköp varor SE omvänd skattskyldighet 25%
+  '4416': '23',  // Inköp varor SE omvänd skattskyldighet 12%
+  '4417': '23',  // Inköp varor SE omvänd skattskyldighet 6%
+  '4425': '24',  // Inköp tjänster SE omvänd skattskyldighet 25%
+  '4426': '24',  // Inköp tjänster SE omvänd skattskyldighet 12%
+  '4427': '24',  // Inköp tjänster SE omvänd skattskyldighet 6%
+
+  // Import beskattningsunderlag → Box 50
+  '4545': '50',  // Import 25%
+  '4546': '50',  // Import 12%
+  '4547': '50',  // Import 6%
 }
 
 /** Swedish labels for each momsdeklaration box */