How is the CUIT check digit calculated?

Multiply the first 10 digits by the fixed weights 5,4,3,2,7,6,5,4,3,2, sum them, take the sum modulo 11, then subtract from 11. A result of 11 becomes 0 and a result of 10 becomes 9.

How accurate is this validator?

The modulo-11 check digit is exact, so an invalid digit is caught reliably. A valid check digit only means the number is well-formed — it does not prove the CUIT is registered with AFIP, which this tool never contacts.

Is my CUIT sent anywhere?

No. The decoder is privacy-first — all processing happens locally in your browser and the number never leaves your device.

Argentina CUIT / CUIL Decoder

Argentina CUIT / CUIL decoder

Decode and validate an Argentine CUIT (tax ID) or CUIL (labour ID). The 11-digit number is structured as a 2-digit type prefix, an 8-digit DNI (for individuals) or company serial, and a final modulo-11 check digit. This tool verifies the check digit, identifies the prefix (male, female, or company), and reads the DNI.

It is privacy-first: nothing leaves your browser. The decoder only verifies the structure and check digit — it never checks the number against any AFIP database.