What is an RFC in Mexico?

The RFC (Registro Federal de Contribuyentes) is Mexico's federal taxpayer registry identifier issued by the SAT. Individuals have a 13-character RFC and companies have a 12-character RFC. It is required on CFDI electronic invoices and most tax filings.

How is the RFC structured?

A persona física RFC is four name letters, a six-digit birth date (YYMMDD), and a three-character homoclave. A persona moral RFC is three name letters, a six-digit incorporation date, and a three-character homoclave. The last character of the homoclave is a check digit.

How is the RFC check digit calculated?

The SAT maps each of the first 12 (or 11) characters to a value, multiplies each by a descending position weight, sums the products modulo 11, and subtracts from 11. A result of 11 maps to 0 and 10 maps to the letter A. This verifier digit is the final character of the RFC.

Does a valid RFC mean the taxpayer is registered?

No. This tool checks the structure and check digit only. It cannot confirm the RFC is actually registered and active with the SAT — for that you must use the SAT's official validation service. A structurally valid RFC can still be unassigned.

Is my RFC sent anywhere?

No. The full structural and check-digit validation runs in your browser. Nothing you enter is transmitted or stored.

Mexico RFC Validator

The RFC (Registro Federal de Contribuyentes) is Mexico’s taxpayer ID, issued by the SAT and required on every CFDI electronic invoice. This validator checks both the structure and the official check digit for individuals (persona física, 13 characters) and companies (persona moral, 12 characters) — entirely in your browser.

How it works

Structure. A valid RFC follows a strict pattern:

Persona física (13 chars): 4 letters from the person’s names, a 6-digit date YYMMDD, then a 3-character homoclave (2 alphanumeric + 1 check digit).
Persona moral (12 chars): 3 letters from the company name, a 6-digit date, then a 3-character homoclave.

The tool validates the letter block, that the date digits form a plausible MMDD, and the alphanumeric homoclave.

Check digit. The final character is a verifier computed by the SAT’s modulus-11 algorithm:

Pad the RFC to 12 positions (persona moral RFCs are left-padded with a space, value 0).
Map each character to a value via the SAT table 0-9, A-Z, Ñ and a blank.
Multiply each character’s value by its position weight (13 down to 2).
Sum the products, take sum mod 11, then the digit is 11 − (sum mod 11); if that is 11 use 0, and if it is 10 use A.

If this computed digit equals the RFC’s final character, the check digit is valid.

Example

For the well-known sample HEGG560427MVZRRL04-style RFCs, the validator confirms the four name letters, parses the 560427 birth date, and recomputes the trailing verifier digit. A mismatch in any block — a wrong date or a transposed homoclave — fails the check.

Notes

A structurally valid RFC with a correct check digit is still not proof of registration. Only the SAT’s official service confirms an RFC is assigned and active. This tool is for client-side pre-validation before you submit a CFDI or store a taxpayer record — and your data never leaves the browser.