How to verify a Japanese supplier's invoice registration

SOROBAN DATA WORKS — GUIDES

If you buy from Japanese suppliers, the registration number printed on an invoice — the "T number" — decides whether you can claim the consumption tax on that purchase as an input credit. But a printed number is only a claim by the supplier. Registrations are granted on application, they can be cancelled later, and a number can simply be copied or mistyped. This guide is the practical procedure for checking a supplier properly, before the invoice reaches your books.

Why this matters more now

When Japan's qualified invoice system started in October 2023, a transitional measure softened the blow: for purchases from suppliers who were not registered, buyers could still claim 80% of the tax amount as a deemed credit. That relief dropped to 70% in October 2026, on a revised phase-down schedule — 50% from October 2028, 30% from October 2030, and nothing after September 2031. The less the transitional measure covers, the more an unregistered supplier costs you — which makes verification a routine accounting control, not a formality.

What to collect from the supplier

The registration number itself: the letter "T" followed by 13 digits, as it appears on their invoices or quotes.
The supplier's legal name, exactly as registered — not a trade name or a brand.
For a corporation, its corporate number. For corporations the 13 digits of the T number are the corporate number, so the two should match digit for digit.

The check, step by step

1. Format first. A registration number is "T" plus 13 digits. Anything else — wrong length, missing "T", digits that do not match the corporate number the supplier gave you — is a reason to ask before you pay, not after.

2. Look the number up in the invoice register. The National Tax Agency publishes the qualified invoice issuer data on its official site, where anyone can search a single registration number for free. Confirm three things: the registered name matches your supplier, the registration date is on or before the invoice date, and there is no cancellation (deregistration) date — or, if there is one, that it falls after the invoice date.

3. Cross-check the company register. Look the same 13 digits up in the NTA's corporate number data. The company should exist there, under the same legal name, at a plausible address. A T number whose digits belong to a different company is the classic sign of a copied number or a master-data mix-up.

4. Record the date of the data. Registers change. Note when you checked and what the register said, so a later question — from an auditor or from your own accounting team — can be answered with the state of the register at the time, not from memory.

5. Re-check on a cycle. A supplier who was registered at onboarding can be deregistered later. For suppliers you pay every month, a periodic re-check of the whole vendor master — not just new names — is what catches that.

In short: a T number is reliable only when three things line up — the number is in the invoice register, the registration covers the invoice date, and the digits belong to the company you are actually paying.

Pitfalls

Sole proprietors are different. Their T number is not a corporate number — they do not have one — so step 3 works differently: there is no company-register entry to cross-check against, and the name in the register is the individual's name, which may not match the shop or trade name on the invoice.
Name mismatches are common and usually innocent. Old company names, kanji variants and renamed companies all produce mismatches against invoices printed from older master data. A mismatch is a prompt to confirm, not automatic proof of a problem.
"Registered" is a date range, not a state. Registration starts on its registration date and can end on a cancellation date. An invoice dated outside that range is not a qualified invoice, even if the supplier is registered today.

Doing this by hand vs. by system

For a handful of suppliers, the official sites above are enough — the lookups are free and public. The manual route stops scaling when the vendor master has hundreds of names, when checks need to happen inside an invoice-processing workflow, or when the whole register needs re-checking every month. That is the point where the same two public datasets are better queried together over an API: one request with a corporate number or T number returns the company record, the registration status and its dates, and the date of the underlying data.

Japan Corporate & Invoice Check API on RapidAPI

Data sources: National Tax Agency corporate number publication data and qualified invoice issuer publication data, used under the Public Data License (v1.0). Results are based on published data and are not an official certification of registration.