How to Get an RFC (Mexican Tax ID) and e.firma as a Foreign Resident

The RFC is the number the SAT uses to identify every taxpayer in Mexico. For individuals it has 13 characters: 4 letters from your name, 6 digits for your date of birth, and a 3-character code (homoclave) the SAT assigns.

As a foreign resident, you will usually need an RFC if you:

• Work for a Mexican employer. Your employer needs your RFC to report your salary and issue payroll receipts. See work permits for residents.
• Earn self-employed or business income in Mexico, or invoice Mexican clients.
• Rent out property in Mexico.
• Buy or sell property. Notaries ask for it, and it matters for capital gains on a sale. See buying property.
• Open some bank or investment accounts. Many banks ask for it. See opening a bank account.

Having an RFC does not by itself mean you owe tax in Mexico. Whether you owe tax depends on your tax residency and income. See taxes for residents.

• Your CURP. The SAT uses it to pull your identity data. Residents usually find it on their residence card. See how to get a CURP.
• A valid residence card (temporary or permanent) and your passport.
• Proof of address in Mexico, such as a recent utility, internet or phone bill. Bring the original.
• An email address you check, and a Mexican mobile number if you have one.

Make sure your name is identical on your CURP, residence card and passport. Small differences cause problems later when employers, banks or notaries match your records.

There are two common ways:

Online with your CURP

The SAT portal lets individuals register in the RFC using their CURP. This often works for people who only need the number or who will be salaried employees. You receive your RFC and can print your constancia de situación fiscal once you have a SAT password.

In person at an SAT office

Book an appointment through the SAT appointment system (citas.sat.gob.mx). Appointments in large cities can be booked up weeks ahead, so check early and often. At the office, an SAT officer registers you, records your tax regime and address, and can issue your password (contraseña). Many foreigners prefer this route because they can ask questions and get the e.firma at the same visit if they book both services.

Choosing a tax regime

You will be asked about your economic activity. Your answer sets your filing duties:

The wrong regime can create monthly filing obligations you do not need, or leave you out of compliance. If you have business or rental income, talk to a Mexican accountant (contador) before you register.

The constancia de situación fiscal is a one or two page SAT document that shows your RFC, your name, your registered address and your tax regime. Employers, banks, landlords and clients often ask for it, especially when they must issue you an electronic invoice (CFDI).

You can download it from the SAT portal with your password or e.firma. Keep your address up to date with the SAT; the constancia shows what the SAT has on file.

The e.firma (formerly called FIEL) is an advanced electronic signature. It is a digital certificate and a private key, protected by a password you choose. With it you can file returns, update your tax data, and sign many official procedures online. Notaries often need it for property deals, and some banks ask for it.

To get it:

1. Book an e.firma appointment at citas.sat.gob.mx.
2. Bring your residence card, passport, CURP, proof of address, an email address, and a USB drive. The SAT website explains how to prepare the request file with its software before the appointment.
3. At the office, the SAT records your photo, fingerprints, iris scan and signature.
4. You leave with your certificate (.cer) and key (.key) files. Store them safely and do not share your password.

The e.firma is valid for 4 years. You can renew it online before it expires; if it lapses, you must go back in person.

• Activate the buzón tributario. This is your SAT online mailbox. The SAT sends official notices there, so register a working email and phone.
• Update the SAT when you move. Address changes must be reported.
• Know your deadlines. Employees whose employers withhold tax may still need to file an annual return in some cases. Self-employed people and landlords usually file monthly and annually.
• Keep your residency and RFC data consistent. When you renew or change your immigration status, check that the SAT still has your correct name and nationality.

For the bigger picture on what Mexico taxes, see taxes for residents. Remote workers should also read remote work rules.