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Overview

Japanese Invoice Registration Number Validator

Batch-validate Japanese qualified invoice registration numbers (T-numbers) for the 2023 Invoice System. Checks syntax, digit count, and mod-11 checksum locally.

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#japanese-invoice-system #t-number-validator #invoice-compliance #nta-registration #consumption-tax-japan

インボイス登録番号（T番号）一括バリデーター

適格請求書発行事業者の登録番号（T番号）をまとめて検証。Tプレフィックス・13桁・チェックデジット（mod-11）をブラウザ内でローカルに確認できます。

このツールはT番号の書式とチェックデジットをローカルで検証します。実際の登録状況の確認は、各有効番号に表示される国税庁照会リンクからご確認ください。

確認するT番号

T番号フォーマットガイド

構成

T + 13桁の数字

合計14文字

例

T1000020483583

国税庁公式サンプル

チェックデジット

13桁の先頭1桁

mod-11方式で検証

受付可能な入力形式: T1234567890123 · T-123-4567-8901-23 · T 1234567890123 · Ｔ１２３４５６７８９０１２３

ハイフン・スペース・全角文字は検証前に自動的に正規化されます。

What you can solve

How do I validate a Japanese qualified invoice registration number (T-number)?

A valid T-number is exactly 14 characters: the letter T followed by 13 digits. The first digit of the 13-digit body is a check digit computed with a mod-11 algorithm. Paste the number into this tool to check both the format and the checksum in one step.

What does a check digit mismatch mean for a T-number?

A mismatch means at least one digit in the number is wrong. Common causes are OCR misread characters (0 vs O, 1 vs l, 8 vs B), missing or extra digits when copying from a PDF, and hyphen positions shifting digit groupings. Compare the number against the original source document to find the error.

How do I validate a batch of Japanese T-numbers at once?

Paste all numbers into the textarea, one per line or comma-separated. The tool validates all of them simultaneously and shows a per-number result. You can then copy only the valid numbers as a clean list, saving the manual work of checking each one individually on the NTA portal.

My T-number has full-width digits from an OCR scan. Will this tool handle them?

Yes. Full-width T (Ｔ) and full-width digits (０-９) are automatically converted to half-width before validation. Hyphens and spaces used for readability grouping are also stripped. The normalized form is shown alongside the original so you can verify the conversion was correct.

How do I confirm a T-number is actually registered with the NTA?

After running validation, each number that passes the checksum check gets a link to the NTA's public invoice registration portal (invoice-kohyo.nta.go.jp). That page shows the business name, registration date, and whether the entity is an active qualified invoice issuer. Checksum validation here is a fast first filter — the NTA portal is the authoritative source.

Typical workflow

CSV ↔ JSON ConverterJapanese Invoice Registration Number ValidatorJapanese Bank Account Batch Formatter

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What is

What is Japanese Invoice Registration Number Validator?

Japan's 2023 qualified invoice system (適格請求書等保存方式) requires businesses to verify supplier T-numbers before claiming consumption tax deductions. Manually checking each T+13-digit number on the National Tax Agency portal works for a handful of invoices, but becomes impractical when auditing monthly batches of 50 or 100 suppliers.

This tool validates the syntax and mod-11 checksum of T-numbers locally in the browser, making it fast to triage a list and identify likely typos or OCR errors before committing to individual NTA lookups.

How to use

How to use Japanese Invoice Registration Number Validator

Paste T-numbers one per line or comma-separated. Full-width characters and hyphens are normalized automatically. Click Validate to see per-number results. Valid numbers include a direct link to the NTA public information portal for official registration verification. Use Copy valid to extract only the passing numbers for your records.

Example

Input batch:
T1000020483583
T1234567890123
T 3-1234-5678-9012

Results:
✓ T1000020483583 — Valid (checksum matches)
✗ T1234567890123 — Invalid (check digit mismatch)
✓ T3123456789012 — Valid (normalized from hyphenated format)

Common use cases

1. Auditing invoice batches to catch OCR errors before submitting tax filings.

2. Pre-validating vendor T-numbers collected in spreadsheets before importing to accounting software.

3. Quick triage of a list of new supplier numbers without opening the NTA portal for each one.

4. Identifying registration number formatting issues in legacy procurement systems.

Frequently asked questions

Does 'Valid' here confirm the business is actually registered?v

No. This tool only checks the format and checksum of the number. A number can pass the checksum check and still not be registered with the NTA. For official registration status, follow the NTA verification link provided for each valid number.

What is the mod-11 checksum and why does it matter?v

The first digit after the T prefix is a check digit calculated from the remaining 12 digits using a mod-11 algorithm defined by the NTA. It can catch single-digit transcription errors. If the check digit does not match, the number almost certainly has a typo somewhere.

Is it safe to paste invoice or vendor data here?v

Yes. All validation runs in your browser. No data is transmitted to any server. Your vendor lists, T-numbers, and invoice data stay entirely on your machine.