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RFC number FAQs

1. What is an RFC number?

RFC stands for “Registro Federal de Contribuyentes” (Federal Taxpayers Registry) and it is Mexico’s federal tax identification number.

2. What is the structure of RFC numbers?

Individuals’ RFC numbers are 13 letters long: four letters for the name, six numbers for the birthdate, and three extra alphanumeric digits called “homoclave” which make the RFC number unique— as the rest of the structure could be shared by more than one taxpayer— and are generated through an algorithm based on the 10 first digits.

The four letters are: the first letter in the paternal last name, the first vowel in the paternal last name or second vowel if the first letter is a vowel, first letter in the maternal last name and the first letter in the first name. In the case of foreigners with no maternal last name, the last two letters in the RFC are the first two letters in their fist name. The six numbers for the birthdate follow the YYMMDD structure.

Corporate RFC numbers are 12 digits long: three letters that stand for the entity’s name, six numbers for the date the company was created, and three extra alphanumeric digits called “homoclave” which make the RFC number unique and are generate through an algorithm based on the 9 first digits. If the company’s name has three or more words on it, the letters on the RFC number are the first letter in the first three words; if they have two words, then the three letters are the first letter in the first word and the first two letters in the second word while if the name is made up of only one word, the first three letters on it are used. The six numbers for the incorporation date follow the YYMMDD structure.

3. How are RFC and CURP numbers different?

The following chart explains differences and similarities between both numbers:




Registro Federal de Contribuyentes (Federal Taxpayers Registry)

Clave Única del Registro de Población

(Unique Population Registry Number)

Issued by

SAT (Servicio de Administración Tributaria, the government agency in charge of Mexico’s internal revenue, appointed by Secretaría de Hacienda, Mexico’s Treasury Department)

RENAPO (Registro Nacional de Población, the national population registry that is part of Secretaría de Gobernación, Mexico’s Ministry of Interior)

Mexican nationals get theirs through the civil registry when their birth is registered. Foreigners—either temporary or permanent residents—are given one by the National Migration Institute when they get residency status.


13 digits for individuals, 12 digits for entities.

18 digits. As it is a population registry, it is only applicable to individuals.


Four letters for the name (as explained above), six numbers for the birthdate in YYMMDD format, and three unique digits generated by SAT’s algorithm in the case of individuals. Three letters for the name, six numbers for the incorporation date in YYMMDD format and three unique digits generated by SAT’s algorithm in the case of entities.

Four digits for the name (in the case of foreigners with no maternal last name, there is an X in the third position), six numbers for the birthdate in YYMMDD format, an H or an M depending on whether you are a man or a woman, two letters for the state you were born in (NE, meaning “Nacido en el Extranjero” for foreigners), the first inner consonant in your paternal last name, the first inner consonant in your maternal last name, the first inner consonant in your first name, a verifying digit (0-9 for people born up to 1999 and A-Z for the ones born as of year 2000.


An RFC number identifies a taxpayer and so it is the number under which taxes are filed.

A CURP number identifies Mexico’s population, whether you are a citizen or a temporary or permanent resident.

Information included in the registry

The Federal Taxpayers Registry, through the RFC number, includes each taxpayer’s: • Name • CURP number in the case of individuals • Fiscal address and branches • Country of tax residency • Fiscal characteristics • Tax obligations • A record of any changes to each taxpayer’s fiscal status

The Population Registry keeps the following information: • Name • Birthdate • Place of birth • Birth certificate number for Mexicans and Immigration document number for foreigners • Parents’ information when minors get their CURP number. • Pictures, fingerprints, and iris scans started being added in 2009.

4. How are they connected?

The CURP number has become a linking number for all the other ones we have; it is linked to our Social Security Number, voter’s number, RFC number, passport number, education databases, driver’s licenses, etc. This is because the CURP number states your legal identity and so linking everything else to it ensures identity protection.

5. Who needs an RFC number?

The 2022 tax reform included a change to Article 27 in the Federal Fiscal Code where they added a paragraph stating that all individuals of legal age (legal age in Mexico is 18 years old) are to get an RFC number regardless of whether they are employed or have a business activity. The reason behind this, as well as the reason behind the change that made it so that RFCs could no longer be issued online but now require an in-person appointment, is that over the years, fiscal identity theft was very common and very easy to accomplish. This is because CURP numbers are basically public: if you know a person’s full name and date and place of birth, you can very easily get their CURP number. This type of identity theft has been mainly used by money laundering and illegal outsourcing and factura selling organizations. This is also why SAT changed the process for obtaining a password to be able to access their online services a few years ago so that they can make sure it is the taxpayer the one who applies for and sets the password.

This went into effect on January 1st, 2022; on January 3rd, SAT issued a press release which can be found here stating that there would be no penalties for individuals who were unemployed or had no business activities and who did not register for an RFC number. This is partly due to the fact that, given the current in-person only RFC registration system, it will take some time for SAT to be able to physically register everyone; on the other hand; the president also spoke on the matter making it clear that the intention behind this reform was not to penalize people but to come up with a better, complete database, and to protect individuals’ from fiscal identity theft.

Based on the above, if you are a temporary or permanent resident, you will eventually need to get registered for an RFC number. If you are also going to have any type of Mexico-sourced income, you must register so you can comply with your Mexican tax obligations.


6. How do I get an RFC number?

RFC numbers are issued by SAT and by appointment only—with the exception of people who are 60+ years old, people with disabilities, and pregnant and lactating women with infants—so you need to make an appointment through their appointment system and bring the required paperwork, as listed below. The registration process itself takes a few minutes that can turn into a few hours depending on how busy the SAT office is.

7. How do I get an appointment?

SAT appointments are made online through an automated system that displays availability at the chosen office or, if there is no availability, gives taxpayers the option of getting in a virtual queue. You can get an appointment here.

8. Are there virtual appointments?

No, the queue is virtual while all appointments are in-person only.

9. Can I get registered through SAT’s virtual office?

No, the only way to get registered is in person at a physical SAT office.

10. What documents do I to get registered for an RFC number?

  • A printout of your CURP number which can be downloaded at here.

  • A pre-registration notice which is filed here.

  • Proof of address which does not have to be in your name. If you are not a Mexican national, it should match the address given to Immigration; otherwise, Immigration will have to be informed of the change of address.

  • Your resident card as official ID if you are foreigner; passport, INE, cédula professional or INAPAM card for Mexican nationals.

11. Is there any way I can file Mexican taxes without an RFC number?

No, all tax returns are filed under each taxpayer’s RFC number and cannot be filed without it.

12. There are websites where you enter your CURP number and they calculate an RFC number, can I use that RFC number?

Those websites mimic SAT’s algorithm for what the homoclave could be so they get it right sometimes and sometimes they do not. RFC numbers are only issued by SAT, so running your CURP number through one of those websites does not mean you are registered on the Federal Taxpayer Registry as that is an official database only SAT can make changes to.

13. How can I know what my RFC number is if the appointment system states that my CURP number is already linked to one?

You can recover your RFC number using your CURP number here. If you don't have all the information needed for the online recovery process, you can go to any SAT office with your official ID (resident card only in the case of foreigners), with no need for an appointment and request an RFC certificate (Constancia de situación fiscal).

If it turns out you already have an RFC number and you cannot recover it online, bank statements and deeds are places to look for. If you find one there and want to validate it, you can do so here.

The reason it is possible to unknowingly have one is that in the past, banks and notaries had the ability to register taxpayers so, if you opened a bank account or bought property, it is possible that you got registered then. Also, up until the point where this became an in-person process only, you could have gotten registered by anyone as it was a simple online process.

14. How can I know for a fact whether I have an RFC number or not?

Since the RFC recovery process requires more information than just the CURP number, the easiest and fastest way of knowing whether you already have one or not is trying to sign up for a registration appointment as, if your CURP number is already linked to an RFC number, you will get an error message stating that.

15. If I have more than one business activity or location, do I need more than one RFC number?

No, RFC numbers are linked to the taxpayer as opposed to individual businesses. A taxpayer can do more than one type of business in more than one location and all income gets filed under the same RFC number.

We hope you found this RFC number FAQs helpful. If you want to get registered for an RFC number, we can assist you with the appointment and pre-registration notice anywhere in Mexico. In Puerto Vallarta and Mexico City we also offer a facilitator who can come to the SAT office with you. You can contact us here and, if you need further assistance, you can book a call here.

Paula Blanco, CPA

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