Compute the check digit from the 12-digit body, or verify a full 13-digit number
A Japanese Corporate Number has 13 digits: one check digit followed by a 12-digit body. The check digit is derived mechanically from the body, so a 13-digit number can be verified on the spot. Conversely, if you only have the 12-digit body, this tool gives you the digit that belongs in front.
Number the 12 body digits from the least significant end. Sum the digits in odd positions and the digits in even positions. Add the odd sum to twice the even sum, take the remainder modulo 9, and subtract it from 9. Because the remainder is between 0 and 8, the check digit is always between 1 and 9.
The calculation only tells you whether the 13 digits are internally consistent. It does not tell you whether the number is assigned to a real company, whether it is still valid, or which company it belongs to. Use the National Tax Agency public site for that. This tool checks the format only.
The value you type is never sent to a server. The JavaScript loaded with the page does the calculation locally.
No. The formula subtracts a modulo 9 remainder from 9, and that remainder is between 0 and 8. The check digit is therefore always between 1 and 9. A 13-digit value starting with 0 is either not a Corporate Number or has been copied incorrectly.
No. The Individual Number has 12 digits and uses a different check digit formula with different weights. This tool is for Corporate Numbers only.
Start with transposed digits and misread characters. The tool also shows the correct check digit, so if only the first digit differs the error is in the leading digit, and otherwise it is in the body.
No. The calculation happens entirely in your browser and no request is made, so a business partner number stays on your machine.