How is the French VAT key computed?

The two-digit control key is (12 + 3 × (SIREN mod 97)) mod 97. The full VAT number is FR, then that two-digit key, then the 9-digit SIREN.

What format is a French VAT number?

FR followed by a 2-character key and the 9-digit SIREN — 13 characters total. The key is usually two digits, but for some older numbers it can contain a letter.

Why does the key sometimes contain a letter?

A small number of historic French VAT numbers use an alphanumeric (old-style) key rather than the modern numeric one. This validator handles the standard numeric key and flags non-numeric keys for manual checking.

Does a valid key mean the VAT registration is active?

No. A matching key only confirms the number is internally consistent with its SIREN. To confirm the registration is active across the EU, query the official VIES service.

Is the VAT number sent anywhere?

No. All computation runs in your browser. Nothing leaves your device and no VIES call is made.

France VAT Number Validator

A French numéro de TVA intracommunautaire is the VAT identification number used for EU cross-border trade. It is built from the company’s 9-digit SIREN plus a 2-digit control key, prefixed with the country code FR. Because the key is derived deterministically from the SIREN, you can validate the whole number offline. This free tool recomputes the key in your browser and checks it against what you entered.

How it works

The French VAT number has the structure FR + KK + SIREN, where KK is the 2-digit control key:

Strip spaces and confirm the number starts with FR and contains a 9-digit SIREN.
Compute key = (12 + 3 × (SIREN mod 97)) mod 97.
Compare that computed key to the two characters after FR.
The VAT number is consistent if they match (and, ideally, the SIREN itself passes its Luhn check).

This is the standard numeric-key formula. A minority of legacy numbers use an old alphanumeric key — those are flagged for manual verification rather than rejected outright.

Example

Take SIREN 732829320. Then 732829320 mod 97 = 43, so key = (12 + 3 × 43) mod 97 = 141 mod 97 = 44. The full VAT number is therefore FR44732829320 (worked here as an illustration of the formula).

Notes

A matching key proves internal consistency, not active registration. For genuine EU compliance you must confirm the number is live in VIES (the EU VAT Information Exchange System). Everything in this tool runs locally — the VAT number never leaves your browser.