My Number & Corporate Number Check Digit Validator
Check whether the check digit of a Japanese My Number (individual number) or Corporate Number is correct. Use it to catch typos, or to confirm that test numbers you generate for software development are well formed. Invoice registration numbers (T + corporate number) can be pasted in as they are. The number never leaves your device. For random identifiers, see the UUID Generator.
🔒 Runs in your browser · Your data is never sent to a server
Enter 12 digits to validate. Enter 11 digits to calculate the 12th digit (the check digit).
Result
Notes
- This tool only checks that the check digit is consistent. It cannot tell whether the number exists, who it belongs to, or whether it is currently valid. To confirm that a corporate number exists, use the National Tax Agency’s Corporate Number Publication Site.
- Numbers are calculated only inside your browser. Nothing is sent, stored or logged.
- A correct check digit does not mean the number was officially issued. Collecting or entering other people’s My Numbers is strictly restricted by Japanese law.
- An invoice registration number is "T" plus the 13-digit corporate number. Sole proprietors’ registration numbers are a separate 13-digit number whose check digit may not follow the corporate number rule, so they are out of scope.
Glossary
Check digit
A digit calculated from the rest of the number to catch entry errors. In a My Number it is the last digit, and in a Corporate Number it is the first. It detects almost all single-digit typos and swaps of neighboring digits.
My Number and Corporate Number
The My Number is a 12-digit number assigned to each resident of Japan and used for tax, social security and disaster-response procedures. The Corporate Number is a 13-digit number assigned to corporations by the National Tax Agency, and anyone can look it up on the public site.
FAQ
Is the My Number I enter sent to a server?
No. The check digit is calculated entirely in your browser. Nothing is sent or stored, and the input is not kept after a reload.
If it says "correct", does the number exist?
No. It only confirms that the check digit is consistent, not that the number exists or is valid. Use the National Tax Agency’s Corporate Number Publication Site to confirm that a corporate number exists.
Can it validate an invoice registration number (T + 13 digits)?
Choose "Corporate Number" and enter the number starting with T. For corporations the registration number is "T" plus the corporate number, so the T is removed before validating. Sole proprietors’ numbers are not covered.
What if I enter one digit fewer?
Enter 11 digits for a My Number or 12 for a Corporate Number and the tool calculates the check digit and shows the complete number. Any other length shows a length error.
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