RFC and CURP for the Foreign Buyer: Law vs. Practice

If you're a foreigner and about to buy a house in Mexico, almost everyone will tell you the same thing: get your RFC and CURP before you sign. It's good practical advice, but it's not what the law requires. The Federal Tax Code does not include the purchase of real estate among the cases that obligate the buyer to register with the RFC. The notary usually asks for it for other reasons. Distinguishing between the two saves you a wasted trip and decisions based on a deadline that doesn't exist.

Do you really need RFC to buy? Law against notarial practice

No. The law does not require you to have RFC simply because you are buying a property. Art. 27, Section A of the Federal Tax Code lists those obligated to register, and the property buyer is not listed there. The purchase and sale is not, by itself, grounds for registration.

The notary's duty to record the RFC in the deed is also limited. The Code itself limits it to one specific case: "Record in public deeds in which the constitutional acts or other meeting minutes are noted, the key in the federal taxpayer registry corresponding to each partner and shareholder or legal representatives". That covers corporate formations and meetings, not home purchases.

So why does the notary ask for it? Because it simplifies their informational report and reduces their risk. But that report, according to the same Code, should only contain "information necessary to identify the contracting parties" — it does not require the buyer's RFC as a requirement to deed.

There is an institutional asymmetry that confirms this. The SAT created form 42/CFF to register the seller through the notary. There is no equivalent form for the buyer. If the law obligated the buyer to register by buying, that channel would exist.

In summary: RFC as a requirement to deed is, in most cases, risk policy of the notary's office, not a direct legal mandate.

Cases where the law will actually require RFC from you (and not for buying)

The obligation to have RFC does not arise from buying; it arises from what you do around the purchase. And there are several scenarios that apply to almost every closing.

• Opening an account in the Mexican financial system. This does generate an obligation to register with the RFC, and it happens at almost every closing: to pay property tax, utilities and receive the property in an orderly manner, you end up needing a local account.
• Renting the property. If you are going to rent, you will need to issue a CFDI, and for that you need RFC.
• Buying well below the appraisal. According to Art. 125 of the Income Tax Law, "when the value of the appraisal exceeds by more than 10% the consideration agreed upon for the transfer, the total of the difference will be considered income of the buyer". That income makes you a taxpayer for acquisition of property.
• The day you sell. Then you will be the seller, and RFC becomes central to calculating withholding and exemptions.

A frequent case among foreigners: purchase in restricted zone is done when you buy via trust, which adds its own mechanics worth understanding before you sign.

Consequence: review what you will do with the property. If you will open an account or rent — the usual case — apply for the RFC anyway. Not because buying obligates you, but because what comes after does.

RFC without residency: what the SAT form actually asks for

The current form is 1/CFF from Annex 2 of the RMF 2026 (DOF 29-Dec-2025), "Application for RFC registration of individuals". Any guide citing "39/CFF" or "Annex 1-A" is outdated: those are dead references and serve precisely to detect old content. You can read the official requirements in the text of Annex 2 and on the procedure page for foreigners.

The central condition is the CURP. The form requires: "Have CURP or, if applicable, temporary CURP with valid photograph. In the case of foreigners who are in national territory, the CURP indicated on the residence cards issued by the competent authority may be considered for registration".

There is a free written statement for those without authorization for paid activity: "they must submit a free written statement in which they declare under penalty of perjury the purposes for which they require the RFC key". Two clarifications that almost no one makes: that statement does not replace the immigration document or CURP, and the form does not say "patrimonial purposes" — it allows you to declare the purposes, whatever they may be.

Here's the hard and honest fact: if you don't have an immigration document and don't have CURP, form 1/CFF does not provide any way to register you. It's not a difficult procedure, it's a bottleneck. Saying it upfront saves you the wasted trip caused by guides that promise otherwise.

The channel is in-person with mandatory appointment. The procedure is free, with immediate resolution, and the RFC has indefinite validity.

CURP: the prerequisite step to RFC

The CURP is assigned by the Ministry of Interior through RENAPO. For the foreigner in national territory, the SAT form accepts the CURP that appears on the residence card, as cited in the previous section.

It comes before RFC for an operational reason: CURP is a condition of procedure 1/CFF, and the SAT validates it against RENAPO during registration. Without a valid CURP, the RFC application does not move forward. You can check the procedure on the CURP portal and schedule on RENAPO appointments.

Consequence: order the procedures in sequence. First CURP — which depends on your migration status — then RFC.

Biometric CURP: what changed with the reform and what didn't

The biometric CURP is mandatory for acceptance, not mandatory for obtaining. The law does not obligate you to apply for it or set a deadline to do so.

The decree was published in the DOF on July 16, 2025 and entered into force on July 17, 2025. It adds 7 articles to the General Population Law — article 91 paragraph 2, and articles 91 Bis, Ter, Quater, Quinquies, Sexies and 114 Bis — and repeals none.

Art. 91 Bis defines CURP with fingerprints and photograph as "the mandatory national identification document, of universal and mandatory acceptance throughout national territory". But the same article clarifies: "The integration of biometric data will be carried out, with the prior consent of the titleholders". Prior consent, without age distinction — it's in the text, not in a memo.

What the key does obligate: Art. 91 Sexies says that "Every public or private entity will be obligated to request the Unique Population Registry Key for the provision of its procedures and services". That obligation is satisfied with the 18-character alphanumeric CURP, without biometrics.

On the supposed "February 2026 deadline": it has no regulatory basis. The deadlines set by the decree — 90 and 120 calendar days from July 17, 2025 — run against the authority to develop platforms and programs, not against the citizen to enroll. No provision sets a deadline for the person.

Does your traditional CURP still work? Yes, and there are two confirmations

Yes. Your traditional CURP remains valid. It starts with verified silence: no provision of the decree invalidates, replaces or sets expiration on non-biometric CURP, and the Regulations to the General Population Law remains unreformed since September 28, 2012.

To that silence are added two positive confirmations. For RFC, form 1/CFF asks for "CURP or temporary CURP with valid photograph", not biometric CURP. To deed, the Notary Law of Quintana Roo does not mention CURP or RFC anywhere in its text.

Consequence: don't pay for unnecessary procedures or rush to enroll by an invented deadline. Your current CURP works to register for RFC and to sign.

Can the notary deny you the deed if you don't have RFC?

The notary law of Quintana Roo asks for the appearing party's details and official ID with photograph, not RFC. There is no mention in its text of RFC or CURP as a requirement of the deed.

As a fact — not as law — a notary can condition the signature on your providing the RFC. It's the risk policy of the office, not a legal mandate that can be pointed to in an article. The SAT format allows generic keys for foreigners in the informational report, but requiring that the notary use them is a negotiation, not an enforceable right.

Before you sign,

verify the land regime before signing: that check is as important as the RFC check.

Practical recommendation: ask the notary's policy weeks before, not the day of signing. If their policy requires RFC, you have time to apply for it; if it appears on the day of the appointment, you stop the closing.

What RFC is useful for after you buy

The moment RFC matters most is not the purchase: it's the sale. That's where income tax withholding calculations come in, the possible exemption for primary residence and verification of acquisition cost to determine gain.

You also need it to rent the property and issue CFDIs, to open a local bank account and to manage property tax and utility payments. That is: RFC is the tool for your fiscal life around the property, not an entry ticket to buy it.

Consequence: even if you buy today for personal use and have no plans to rent, having the RFC ready simplifies the day you sell — which is when the number stops being optional.

Frequently asked questions

Can I be fined if I don't apply for biometric CURP?

Not for failing to apply for it. Art. 114 Bis of the General Population Law sets a fine of 10,000 to 20,000 times the daily value of the UMA for violating the obligations of Art. 91 Bis, but it falls on authorities and individuals obligated to the duties of that article, not on the citizen who doesn't enroll. The equivalent in pesos depends on the current value of the UMA.

Is biometric CURP mandatory for my minor children?

The decree does not establish that obtaining biometric CURP is mandatory for minors. The integration of biometric data requires prior consent of the holder, according to Art. 91 Bis, without age distinction. The decree deadlines involving minors run against the authority — to develop an integration program — not against families to enroll their children.

Do I need e.firma if I get RFC just to buy?

Form 1/CFF from Annex 2 of the RMF 2026 governs RFC registration, which is free and with immediate resolution. If your goal is solely to register, that is the procedure you resolve; e.firma is a different tool, linked to operations that require electronic signing. Consult with your advisor if your specific case will need it.

This information is of a general nature and does not replace the advice of a public accountant or tax specialist, with notarial validation at the point of deed execution. At Propyte we can help you organize your CURP and RFC procedures according to your migration status before signing: schedule with an advisor and reach closing without surprises.