Mexican ID Numbers Explained - CURP, RFC, and More

CURP is your Mexican population ID (like a US SSN), you get it automatically with your resident visa. RFC is your tax ID, required for banking, property, and earning income. Both are essential for expat life in Mexico. Here's how to get and use them in Puerto Morelos and throughout Mexico.

CURP - Your Unique Population Registry Code

What is it?

The CURP (Clave Única de Registro de Población) functions similarly to a U.S. Social Security Number or Canadian SIN. It's your unique identifier in Mexico's population registry system.

How do you get it?

Good news - you don't have to do anything special. Immigration automatically issues your CURP when you receive your temporary or permanent resident card. Your CURP number is usually printed on the front of your resident visa.

How to access your CURP

Need to look up or print your CURP? The government provides an online portal at gob.mx/curp where you can:

• Enter your CURP number if you know it (select "Clave Única de Registro de Población")
• Look it up using your personal data if you don't know the number (select "Datos Personales" and enter your names, birth date, and birthplace - select "NACIDO EN EL EXTRANJERO" if born outside Mexico)

The New Biometric CURP (As of October 2025)

Mexico began issuing biometric CURP cards in October 2025. This new version serves as a more strong official identification document.

What it includes:

• Digital photograph
• Fingerprints
• Iris scan
• Digital signature
• Birth date, sex, birthplace, and nationality

Who needs it: The biometric CURP is required for school enrollment (mandatory since November 2025), government social programs, banking, education, and public healthcare access.

Requirements for residents: Temporary and Permanent residents need a birth certificate with an apostille.

RFC - Your Tax ID Number

What is it?

The RFC (Registro Federal de Contribuyentes) is your personal tax identification number, similar to a U.S. ITIN. The federal government now requires every resident of Mexico age 18 and older to register with SAT (the tax authority) and obtain an RFC, regardless of income or tax status.

When do you need an RFC?

You'll need your RFC for many common activities:

• Opening a bank account
• Earning income paid in Mexico
• Collecting rent as a landlord
• Selling property
• Getting Starlink satellite internet
• Purchasing a vehicle
• Signing up for utilities
• Receiving courier items and Amazon purchases from outside Mexico

Important: Tourists cannot obtain an RFC, which limits their ability to complete many of these transactions.

RFC Structure

Your RFC is a 13-character code made up of:

• Four letters derived from your paternal surname, maternal surname, and given name
• Six-digit birth date (YYMMDD format)
• Three-digit checksum assigned by SAT

How to Get Your RFC

1. Request an appointment online through SAT's website (sat.gob.mx)
2. You'll receive an email weeks later - you must reply within 24 hours or the appointment cancels
3. Go to your local SAT office with:
   • USB drive
   • Resident card
   • Printed CURP
   • Proof of address

RFC Validity and Renewal

The RFC itself doesn't expire, but the electronic signature expires after 4 years and requires renewal at a SAT office.

The Constancia Requirement

Temporary and Permanent Residents and citizens over 18 must also obtain a Constancia - a document that contains key information about taxpayers and includes a QR code proving current tax status. This validates your economic activity.

International Parcel Requirements

Here's something that catches many expats off guard: to receive packages from outside Mexico, you must provide either a CURP or RFC. Without one of these numbers, your item may not clear Customs (Aduana).

Quick Reference

Tips for Success

• Keep copies of all your ID numbers in a safe place
• Book your SAT appointment early - wait times can be long
• Respond to SAT emails within 24 hours or lose your appointment
• Bring a USB drive to SAT appointments
• Get your apostilled birth certificate before applying for the biometric CURP
• Remember that your RFC electronic signature expires every 4 years

Final Thoughts

Mexico's ID number system might seem complicated at first, but once you understand what each number is for, it makes sense. Get your CURP and RFC sorted early in your residency - you'll need them for almost everything official you do in Mexico.

Questions about Mexican ID numbers? Drop them in the comments!

Related Mexico Expat Guides

• Benefits of Mexican Residency
• Buying Property in Mexico
• Legal Services in Puerto Morelos

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