The RFC (Registro Federal de Contribuyentes) is Mexico’s tax identification number. Yes, you need one. Banks require it to open accounts. You need it to buy property, start a business, or sign certain contracts. Get it from SAT after you have your residency card and CURP.
What Is the RFC?
The RFC is a unique alphanumeric code that identifies you in Mexico’s tax system. SAT (Servicio de Administracion Tributaria), Mexico’s federal tax authority, issues it. Think of it as Mexico’s equivalent of a US Social Security number for tax purposes.
Your RFC contains 13 characters. The first four come from your name and birth date. SAT assigns the remaining characters. Once issued, your RFC stays with you permanently. It does not expire or change if you move within Mexico.
Who Needs an RFC?
Any foreign resident who does any of the following needs an RFC. Opening a Mexican bank account. Earning income in Mexico through employment, freelance work, rental, or business. Buying or selling real estate. Starting or owning a business. Issuing or receiving official invoices (facturas). Filing Mexican taxes.
If you moved to Baja and plan to do anything beyond existing as a tourist, you need an RFC. Even retirees who only receive foreign pension income often need one for banking.
Tourists and visitors on FMM permits cannot get an RFC. You must hold a temporary or permanent residency card.
What Do You Need Before Applying?
Your residency card comes first. INM issues your temporary or permanent residency card, and that card triggers your CURP assignment. You need both before SAT will process your RFC application.
Gather these documents before your SAT appointment. Bring the originals and two photocopies of each. SAT offices do not always have copiers available.
Your temporary or permanent residency card (original). Your CURP printout from gob.mx/curp. Your passport. Proof of address (comprobante de domicilio) dated within the last three months. CFE electricity bills, water bills, or internet bills in your name all work. A USB flash drive. SAT saves your e-firma digital signature files to your flash drive during the appointment.
How Do You Get the RFC?
Step 1: Complete the Pre-Capture Form Online
Before your appointment, visit the SAT portal at sat.gob.mx and complete the pre-capture form (forma precaptura). This online form collects your personal information, address, and the tax regime you plan to register under. Print the completed form and bring it to your appointment. Completing this form in advance saves significant time at the SAT office.
Step 2: Schedule a SAT Appointment
Book your appointment through citas.sat.gob.mx. Select your nearest SAT office and choose an available date. Appointments fill fast in cities like Tijuana and La Paz. If no slots show as available, join the waiting list. SAT emails you when a slot opens. Book as early as possible after receiving your residency card.
Step 3: Attend the Appointment
Arrive on time with all documents, photocopies, your printed pre-capture form, and your USB flash drive. The SAT officer verifies your identity, checks your documents against their system, and registers you. The process takes 30 minutes to one hour depending on the office.
During the same appointment, SAT creates your e-firma (firma electronica). This digital signature is a cryptographic file that serves as your legal electronic identity for all SAT interactions. The officer takes your photo, scans your fingerprints, and generates the e-firma files. SAT saves three files to your USB drive: your certificate (.cer), your private key (.key), and a password you create during the appointment. Guard these files. You need them to file taxes, update your tax profile, and access SAT’s online systems.
Step 4: Receive Your RFC
You receive your RFC number the same day. SAT prints a confirmation document (constancia de situacion fiscal) showing your RFC, registered address, and tax regime. Keep this document. Banks, employers, landlords, and notaries all request it.
What Is the E-Firma and Why Does It Matter?
The e-firma is your digital signature for interacting with SAT online. Without it, you cannot file tax returns electronically or update your address or tax regime. You also cannot respond to SAT notifications or access your Buzon Tributario (SAT’s official electronic mailbox).
Your e-firma expires every four years. Renew it before expiration at a SAT office or through the SAT portal if your current e-firma is still active. If it lapses, you must schedule another in-person appointment to reactivate it.
What Is the Buzon Tributario?
The Buzon Tributario is SAT’s official electronic mailbox. After registering your RFC, SAT requires you to activate your Buzon Tributario. This is where SAT sends official notifications, audit requests, and other communications.
Activate it through the SAT portal using your e-firma. Failing to activate it can trigger fines of $3,850 to $11,540 pesos. Many expats skip this step and discover the fine months later. Activate it the same week you get your RFC.
What Are Your Tax Obligations After Getting an RFC?
Having an RFC does not automatically mean you owe Mexican taxes. Your tax obligations depend on your tax regime and income sources.
If you register under the “sin obligaciones fiscales” (without tax obligations) regime, you have minimal filing requirements. This regime works for retirees and people who only receive foreign-source income. You still need the RFC for banking and property transactions, but SAT does not expect monthly or annual tax filings from you.
If you earn income in Mexico (salary, freelance, rental, or business), you must file monthly provisional tax returns and an annual tax return. Mexico taxes worldwide income for residents who spend more than 183 days per year in the country. Consult a Mexican tax accountant (contador) to determine your correct regime and obligations. Tax mistakes in Mexico generate fines quickly.
Common RFC Mistakes Expats Make
Registering under the wrong tax regime. The regime determines your filing obligations. If the SAT officer registers you as an active business when you are a retiree, you face monthly filing requirements you do not need. Tell the officer your situation clearly. Bring a translator if needed.
Forgetting to activate the Buzon Tributario. SAT sends fines electronically to your Buzon. If you never activated it, you never see the notification. The fine still accumulates.
Losing the e-firma files. The three files on your USB drive are your digital identity. If you lose them, you must schedule another SAT appointment to regenerate them. Back up the files to a secure cloud drive or a second USB immediately.
Not bringing photocopies. SAT offices reject applications when you lack copies of your documents. Some offices have no copier. The nearest copy shop may close before your appointment ends. Bring two copies of everything.
Ignoring annual filing deadlines. Even if you owe zero pesos in tax, some RFC regimes require you to file an annual declaration by April 30. Missing the deadline triggers automatic fines. A Mexican contador can file for you for $1,000 to $3,000 pesos per year.
Regulations and government processes change. This article reflects information current as of March 2026. For advice specific to your situation, consult a licensed immigration consultant or contact the relevant government office directly.