Validate a Japanese invoice registration number
Check a qualified invoice issuer registration number — “T” plus thirteen digits.
Type a number and it is checked as you go. The calculation runs in your browser; nothing is sent.
What the number is
Every qualified invoice issuer (適格請求書発行事業者) is issued a registration number: the letter T followed by thirteen digits. For a corporation those thirteen digits are its corporate number (法人番号). For a sole trader they are not, though they come from the same numbering scheme.
Sole traders are not exempt from the check digit
Measured over the whole register on 2026-09-05 — the full monthly file plus the newest daily diffs, 5,421,496 numbers — every one passes the check digit. Corporations, sole traders and unincorporated associations alike, with zero exceptions. A sole trader’s thirteen digits are not a corporate number (none of 50,000 sampled appear in the corporate register), but the check digit still holds. So the number alone cannot tell you which kind of entity it belongs to; only a lookup can.
Common questions
What format is a Japanese invoice registration number?
“T” followed by 13 digits. For a corporation those digits are the corporate number (法人番号).
Is a valid check digit enough to accept an invoice?
No. It shows the number is well-formed. Whether it is registered, and whether it was registered on the date of the invoice, both need the register.
Do sole traders’ numbers have a check digit?
Yes. Measured across the whole register, all 2,726,018 sole-trader registration numbers satisfy it.