How is the NIR control key calculated?

The key equals 97 minus (the 13-digit base number modulo 97). For Corsica, the department codes 2A and 2B are substituted before the modulo, so the base is converted to a number and offset per the INSEE rule. This tool implements that algorithm exactly, including the Corsica case.

Does a valid key mean the NIR is real?

No. A valid key means the number is internally consistent and free of common typos. It cannot confirm the NIR is issued or belongs to a specific person — only the social-security administration holds that record.

Is my NIR sent anywhere?

No. Validation is entirely client-side — the number never leaves your browser and there are no network requests at all.

France NIR / Numéro de Sécurité Sociale Validator

France NIR validator

Enter a French NIR (numéro d’inscription au répertoire, the numéro de sécurité sociale) and the tool decodes the sex, birth month and year, department, commune and order number, then verifies the two-digit control key.

The key is computed as 97 minus the 13-digit base modulo 97, with the special substitution for the Corsica department codes 2A and 2B handled correctly.

Privacy-first: your NIR is processed entirely in your browser — nothing is uploaded or sent anywhere. The tool validates the documented format only and does not query any government database.