Japan Qualified Invoice (インボイス) Compliance Checker

Check whether Japanese invoices actually meet the Qualified Invoice System (適格請求書等保存方式) requirements before you claim input consumption tax credit (仕入税額控除) — in bulk, deterministically, with no AI guesses.

Other tools only tell you whether a T-number is registered. This Actor checks the invoice itself:

Check	What it catches
Required fields	Missing issuer name, registration number, transaction date, line descriptions, recipient (standard invoices)
Registration number	Not T + 13 digits (full-width / hyphens are normalized first), corporate-number check-digit mismatch (typo detection, offline)
Reduced-rate marking	8% items not marked as reduced-rate (e.g. ※)
Per-rate totals	Missing 10% / 8% totals, totals that don't match the line items, invalid tax rates
Tax rounding rule	Tax must be rounded once per tax rate per invoice. Detects per-line rounding and wrong tax amounts; accepts floor, round-half-up and ceiling
Grand total	Grand total that doesn't add up (warning)

Supports standard qualified invoices (適格請求書) and simplified ones (適格簡易請求書, recipient optional, tax amount or rate), and tax-exclusive or tax-inclusive pricing.

Pure computation: no scraping, no API keys, no data leaves the run.

Input

{
  "strict": false,
  "invoices": [
    {
      "id": "INV-0001",
      "invoiceType": "standard",
      "issuerName": "株式会社サンプル商事",
      "registrationNumber": "T1180301018771",
      "recipientName": "株式会社テスト",
      "transactionDate": "2026-10-01",
      "priceBasis": "exclusive",
      "reducedRateIndicated": true,
      "lineItems": [
        { "description": "コピー用紙", "amount": 5000, "taxRate": 10 },
        { "description": "お茶", "amount": 1980, "taxRate": 8, "reducedRateMark": true }
      ],
      "rateSummaries": [
        { "taxRate": 10, "amount": 5000, "taxAmount": 500 },
        { "taxRate": 8, "amount": 1980, "taxAmount": 158 }
      ],
      "grandTotal": 7638
    }
  ]
}

Field	Notes
invoiceType	standard (default) or simplified
priceBasis	exclusive (default) or inclusive
lineItems[].taxRate	10, 8, 0 (non-taxable), also "10%" or 0.1
lineItems[].taxAmount	Optional. If given, used to detect per-line rounding
reducedRateIndicated	true if the invoice has a legend such as "※は軽減税率対象"
strict	Treat warnings as failures

Amounts may be numbers or strings like "１,９８０円".

Output

One dataset item per invoice:

{
  "id": "INV-0002",
  "status": "FAIL",
  "compliant": false,
  "errorCount": 1,
  "errors": [
    {
      "code": "LINE_LEVEL_ROUNDING",
      "severity": "error",
      "field": "rateSummaries[8%].taxAmount",
      "message": "8% tax 78 equals the sum of per-line rounded taxes. Rounding must be done once per tax rate per invoice.",
      "messageJa": "8%の消費税額78が明細ごとの端数処理の合計になっています。…"
    }
  ],
  "warnings": [],
  "taxBreakdown": [
    { "taxRate": 8, "lineItemTotal": 999, "expectedTax": { "floor": 79, "roundHalfUp": 80, "ceil": 80 },
      "reportedAmount": 999, "reportedTax": 78, "roundingMethodDetected": null }
  ]
}

status is PASS, WARN or FAIL. A run summary is saved to the key-value store as SUMMARY.

Typical pipeline

OCR / invoice-extraction tool → this Actor → accounts-payable approval. Pair it with a T-number registry lookup Actor to also confirm the issuer was registered on the invoice date.

Limitations

• Does not query the NTA registry; it checks format and check digit only.
• Check-digit mismatch is a warning, because the algorithm is defined for corporate numbers.
• Whether an item legally qualifies for the 8% rate is not judged; only that 8% items are marked.
• This is a validation aid, not tax advice.

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日本語概要

請求書データ(JSON)が適格請求書の記載要件を満たしているかを一括で検証します。チェック対象は、登録番号の形式とチェックデジット、必須項目の漏れ、軽減税率対象の表示、税率ごとの合計、そして「1請求書につき税率ごとに1回」の端数処理ルールです。適格簡易請求書と税込・税抜の両方に対応しています。外部通信はなく、計算のみで判定します。

詳しい解説記事（Qiita）: インボイスの「端数処理ミス」と源泉徴収の「10%計算ミス」をPythonで一括検出する