International · Mexico
Mexico RFC validator.
Validar RFC: check whether a Mexican RFC has the right shape (13 characters for an individual, 12 for a company), a real date, and a last character that matches the check-digit formula. It runs in your browser and does not look the RFC up.
How it works: an individual RFC is 4 letters, a YYMMDD date and a 3-character homoclave; a company RFC is 3 letters, the date and the homoclave. The last homoclave character is a check character: each of the first 12 characters (company RFCs padded with a leading space) is turned into a number, multiplied by 13, 12, … 2, summed, and the check is 11 − (sum mod 11), where 11 is written 0 and 10 is written A.
Inputs
Result
Enter a number and press Check.
How the check works
| Part | What happens |
|---|---|
| 1 | Map characters to values: 0-9 are 0-9, A-N are 10-23, & is 24, O-Z are 25-36, space is 37, Ñ is 38 |
| 2 | Pad a 12-character company RFC with one leading space, then take the first 12 characters |
| 3 | Multiply by 13, 12, 11 … 2 and add the products |
| 4 | Check = 11 − (sum mod 11); 11 becomes 0 and 10 becomes A |
Worked example GODE561231GR: values 16, 25, 13, 14, 5, 6, 1, 2, 3, 1, 16, 28 times 13 down to 2 add up to 1026; 1026 mod 11 = 3; 11 − 3 = 8. The full RFC is GODE561231GR8.
What this does not tell you
python-stdnum, the reference implementation used here, warns that a small share of RFCs in real use do not satisfy the formula, which is why a mismatch on a correctly shaped RFC is shown as a warning and not as proof of a typo. The SAT register is the only way to know whether an RFC is registered and active. This tool does not check the reserved-word substitutions applied to the first four letters.
Sources
python-stdnum, stdnum/mx/rfc.py; SAT, Consulta de RFC (official register). Retrieved 16 October 2026.
Official register: SAT, Consulta de RFC. Open it in a new tab and enter the number there; this page never sends the number anywhere.
Frequently asked questions
Does a valid result mean the RFC is registered with the SAT?
No. It only means the shape, the date and the check character are consistent. Use the SAT Consulta de RFC to confirm a registration.
Why does a real RFC sometimes fail the check?
The reference implementation notes that some RFCs in use do not satisfy the formula. When the shape is right but the check character differs, treat it as a prompt to confirm on the SAT site.
What is the homoclave?
The last three characters of the RFC. Two distinguish people or companies with the same name and date, and the last is the check character this tool tests.
Format and check digit only — not an official lookup
This tool works entirely in your browser. A passing result does not prove that a number was issued, is active, or belongs to anyone, and it is not verification by any government. Nothing you type is transmitted, stored or logged.