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.

What is the difference between a CUIT and a CUIL?

A CUIT (Clave Única de Identificación Tributaria) is the tax ID used by businesses and the self-employed, while a CUIL (Clave Única de Identificación Laboral) identifies employees for social-security purposes. They share the same 11-digit structure and check-digit algorithm.

What does the prefix 20, 27 or 30 mean?

The two-digit prefix indicates the holder's type. 20 is a male individual, 27 a female individual, 23 and 24 are ambiguous-DNI individuals, and 30, 33 and 34 are companies (personas jurídicas).

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

The Argentina CUIT / CUIL Decoder reads and validates the 11-digit identification numbers used in Argentina: the CUIT (tax ID for businesses and the self-employed) and the CUIL (labour ID for employees). It tells you whether the check digit is correct, what type of holder the prefix indicates, and the DNI or company serial embedded in the middle.

How it works

A CUIT/CUIL is structured as TT-DDDDDDDD-C: a 2-digit type prefix, an 8-digit DNI (for individuals) or company serial, and a final modulo-11 check digit. The check digit is computed by multiplying the first 10 digits by the fixed weights 5, 4, 3, 2, 7, 6, 5, 4, 3, 2, summing the products, taking the sum modulo 11, and subtracting that from 11. A result of 11 becomes 0; a result of 10 means the prefix is bumped (to 23). The prefix is then mapped to a holder type.

Prefix	Meaning
20	Male individual
27	Female individual
23 / 24	Individual (gender resolved by check digit)
30 / 33 / 34	Company (persona jurídica)

Example

Take 20-12345678-6. The first 10 digits weighted and summed give a modulo-11 result whose check digit is 6, matching the last digit — so the number is valid, the prefix 20 marks a male individual, and the embedded DNI is 12345678.

It is privacy-first: the decoder only verifies the structure and check digit and never contacts any AFIP database. Nothing leaves your browser.