México · SAT RFC
Mexico RFC Validator
Validate a Registro Federal de Contribuyentes (RFC) for format and check its status in the SAT taxpayer register before you issue a CFDI.
What is an RFC in Mexico?
The RFC (Registro Federal de Contribuyentes) is the tax ID the Servicio de Administración Tributaria (SAT) assigns to every taxpayer: 12 characters for companies and 13 for individuals, built from name letters, a six-digit date and a three-character homoclave — for example ABC010101AB1. Both parties’ RFCs are required on CFDI invoices.
Mexican RFC format
Name letters, a YYMMDD date and a three-character homoclave whose final character is 0–9 or A.
(3 company, 4 individual)
(incorporation / birth)
(final character 0–9 or A)
Format example only: ABC010101AB1 (persona moral). An individual adds a fourth letter, e.g. PELJ900515AB7.
- 12 or 13 characters: SAT’s CFDI schema defines persona moral RFCs as 3 letters and persona física RFCs as 4 letters, followed by a valid date and 3 characters. No spaces, hyphens or MX prefix.
- Allowed letters: A–Z plus & and Ñ in the name segment — many third-party validators wrongly reject them. Enter it in upper case.
- Final character: SAT’s schema allows only a digit 0–9 or the letter A in the last position. It is widely treated as a check character, but SAT does not publish a formula.
- Incomplete RFCs: A 10-character “RFC sin homoclave” is not a complete RFC, and an 18-character code is a CURP, not an RFC.
How to validate an RFC
- 1 Get the full RFC with homoclave from your customer’s Constancia de Situación Fiscal or a previous CFDI.
- 2 Enter it above. The checker validates the structure, then checks the RFC against the SAT taxpayer register and shows its status.
- 3 For CFDI 4.0, also confirm the customer’s exact name and fiscal postcode — they must match SAT’s records for the invoice to stamp (the postcode rule does not apply to generic RFCs).
- 4 Validating RFCs in bulk? The Lookuptax API checks each one against the SAT register and plugs into your billing system.
Frequently Asked Questions
How do I check if an RFC is valid? (¿Cómo validar un RFC en el SAT?)
Enter it in the checker on this page, which validates the format and checks the RFC against the SAT taxpayer register — no contraseña or e.firma needed. See our Mexico tax ID guide for more on the RFC.
How many characters is a Mexican RFC?
13 for individuals (personas físicas): four letters, a six-digit date and a three-character homoclave. 12 for companies (personas morales): three letters, the six-digit date of incorporation and the homoclave. The letters may include & and Ñ.
What are the generic RFCs XAXX010101000 and XEXX010101000?
They are SAT’s generic RFCs for CFDI invoices: XAXX010101000 for the general public (público en general) and XEXX010101000 for foreign residents, used with tax regime 616 and CFDI use S01. Neither belongs to a registered taxpayer, so a register check reports them as not registered.
Does an RFC check return the company name?
No. An RFC check confirms whether the RFC is valid in SAT’s taxpayer register; it does not return a name or address, and an RFC cannot be found by searching a company name — you need the RFC itself.
What is the difference between RFC and CURP?
The RFC is SAT’s tax ID — 12 characters for companies, 13 for individuals. The CURP is an 18-character population ID issued by RENAPO to individuals only. An individual’s RFC and CURP usually start with the same name letters and birth date.
Is the RFC required on CFDI 4.0 invoices?
Yes. CFDI 4.0 requires both the issuer’s and the receiver’s RFC, and the receiver’s RFC must be registered and not cancelled with SAT unless it is a generic RFC. Checking a customer’s RFC before stamping avoids rejected invoices.
Last reviewed: , against official sources.
Validate RFCs before every CFDI
Check Mexican RFCs against the SAT register in one API call — and tax IDs in 120+ other countries.