US Citizens Buying in Mexico: FIRPTA, Tax Treaties, and What to Declare

What FIRPTA is - and what it is not

FIRPTA is one of the most misunderstood US tax concepts in the context of Mexico real estate purchases. Here is the precise definition: FIRPTA (Foreign Investment in Real Property Tax Act) is a US law that requires a buyer who purchases US real estate FROM a foreign seller to withhold a percentage of the purchase price and remit it to the IRS. The withholding rate is typically 15% of the gross sales price for residential properties over $300,000.

FIRPTA has NO application whatsoever when a US citizen buys Mexican real estate. You are not a foreign seller; you are an American buyer purchasing property outside the US. The Mexican transaction is outside US jurisdictional reach under FIRPTA entirely.

Where FIRPTA does become relevant: if a US citizen eventually sells their Mexican property to a US buyer through a US-registered entity. This is an unusual structure; most Riviera Maya transactions involve Mexican-domiciled trusts (fideicomisos) and are not subject to FIRPTA on sale.

How the purchase is treated on your US taxes

Buying Mexican real estate does not itself trigger a US tax event. The purchase price is your cost basis for future US capital-gains reporting. Keep all closing documents (escritura, Notario invoice, ISAI receipt, any improvement costs) meticulously - they establish your adjusted cost basis when you eventually sell.

If you pay in USD from a US account, no currency-conversion issues arise at purchase. If you hold Mexican pesos in a Mexican account and transfer from a peso account, the FX conversion is handled at the exchange rate on the date of each payment. Record every wire and its exchange rate.

The fideicomiso trust itself does not create a US tax obligation at formation. However, if the bank trust is classified as a grantor trust (which it typically is under US tax principles), you own the beneficial interest directly and report income and gains as if you own the property outright - as you would with any other real estate you hold. There is no separate trust-entity tax return in most cases, but verify this with your CPA.

The US-Mexico Tax Treaty: what it covers

The United States and Mexico have had an active income tax treaty since 1992 (updated by protocol over the years). The treaty's key benefit for property buyers:

• Elimination of double taxation: capital gains on Mexican property sold by a US resident are taxed in Mexico at source; the US taxes the same gain but credits the Mexican tax paid. You do not pay both countries the full rate - the treaty ensures a credit mechanism.
• Rental income: rental income from Mexican property is taxable in Mexico. You also report it on your US return, but claim a foreign tax credit for Mexican taxes paid. Effective double taxation of the same rental income is prevented under Article 6 and Article 22 of the treaty.
• Estate tax: the US-Mexico estate tax treaty (a separate treaty from the income treaty) provides relief from double taxation of inherited Mexican real estate for US citizens. Estate planning with cross-border real estate requires a specialized estate-planning attorney - this is not a DIY area.
• The treaty does NOT eliminate Mexican withholding on Mexican-source income. When you sell Mexican property through a fideicomiso, the Notario withholds Mexican ISR (Impuesto Sobre la Renta) on the capital gain. You receive a certificate of that withholding, which is your documentation for the US foreign tax credit.

Rental income: how both countries tax it

If you rent your Mexican property (Airbnb, VRBO, or long-term), both countries have a claim on that income. Here is how it works in practice:

• Mexico taxes Mexican-source rental income. As a non-resident of Mexico (which most US buyer-owners are), you pay Mexican ISR on net rental income from Mexican property. The rate for non-residents on rental income is generally 25% on gross or 35% on net, via annual filing with SAT (Mexico's tax authority) through a Mexican tax representative (representante fiscal).
• You must file Mexican tax returns if you have Mexican-source income. This requires a RFC (Registro Federal de Contribuyentes) - a Mexican tax ID. Many foreign buyers operating Airbnb-style rentals skip this; it creates tax exposure. A Mexican accountant (contador público) can handle this filing for $300-600 USD/year for a straightforward short-term rental.
• The rental income is also reportable on your US Form 1040, Schedule E. You claim a foreign tax credit (Form 1116) for Mexican ISR paid. The net effect is that you pay the higher of the two countries' rates on the rental income - not both rates stacked.
• Airbnb and VRBO collect and remit Mexican IVA (16% VAT) and ISR withholding automatically for Mexican properties since 2020 under Mexico's platform-economy tax rules. You still owe the annual SAT filing and potentially additional ISR; platform withholding is not a full-settlement.

Capital gains when you sell

When you sell your Mexican property, two events occur simultaneously: Mexico withholds capital-gains tax (ISR) through the Notario at closing, and you have a US capital-gains obligation that you report on your federal return.

Mexican capital-gains calculation: based on the difference between the indexed acquisition cost (original price + closing costs + improvements, indexed for inflation via INPC) and the sale price. The Notario applies the statutory formula. Non-residents typically face a withholding of either 25% on the gross sale price or 35% on the net gain - whichever is lower. You may elect the net-gain method by presenting your RFC and documented deductible costs.

US capital-gains calculation: your US basis is your original acquisition cost plus improvement costs (NOT inflation-indexed - the US does not allow inflation indexing). The gain = sale proceeds minus US basis. Long-term capital gains rates (0%, 15%, or 20% depending on income) apply if you held the property over one year. Net Investment Income Tax (NIIT) of 3.8% may also apply if income exceeds thresholds.

Foreign tax credit: the Mexican ISR withheld and remitted reduces your US tax dollar-for-dollar (up to your US tax liability on that income). In most scenarios with equal-rate countries, you end up paying the higher rate effectively, not both.

FBAR and FATCA: when you need to file

Two additional US reporting requirements apply if you hold financial assets in Mexico:

• FBAR (FinCEN Form 114): required if you hold, at any point in the year, an aggregate of $10,000 or more in foreign financial accounts (including Mexican bank accounts used for property management, rental income collection, or trust-related payments). Filed annually via FinCEN; deadline April 15, auto-extended to October 15. The penalty for willful non-filing can be the greater of $100,000 or 50% of the account balance per violation.
• Form 8938 (FATCA): required if you hold specified foreign financial assets above certain thresholds (single filer: $50,000 year-end or $75,000 at any point; married filing jointly: $100,000/$150,000). A fideicomiso (bank trust) may qualify as a specified foreign financial asset depending on its structure; your CPA must evaluate. Filed with your Form 1040.
• The fideicomiso trust account itself: the trust-holding bank account (held by the Mexican bank as trustee) may or may not be YOUR foreign financial account for FBAR purposes. IRS Notice 2010-23 and subsequent guidance address this - it depends on whether you have signatory authority or a financial interest. This is a specialist area; do not self-diagnose.
• Failure to file FBAR is not a criminal conviction by itself, but civil penalties are severe. Most US buyers with Mexican property and a Mexican bank account have FBAR exposure they are unaware of. A CPA consultation before your first purchase costs far less than a penalty.

The pre-purchase checklist: US tax actions

Before completing a Riviera Maya purchase, every US buyer should take these steps:

• Consult a US CPA with cross-border expertise. The intersection of FIRPTA, FBAR, FATCA, the US-Mexico treaty, and state-level tax (some US states tax foreign-source income) requires a specialist. Cost: $500-2,000 for a pre-purchase consultation and strategy.
• Obtain a RFC (Mexican tax ID) before or immediately after purchase. Required for any tax filings in Mexico. Your Mexican closing attorney or a Mexican contador can help you obtain this - the process takes 2-4 weeks.
• Document your cost basis precisely at closing: purchase price, closing costs (Notario fees, ISAI transfer tax, trust setup fees), and any immediately incurred capital improvements. These are not recoverable later if not documented at time of transaction.
• Set up a separate Mexican bank account for property-related income/expense if you will be renting. Makes FBAR reporting straightforward and separates your rental accounting from personal funds.
• Create a folder (digital + paper) for: escritura (deed), fideicomiso trust agreement, Notario receipt, closing cost breakdown, all wire transfer confirmations, improvement invoices. This is your US cost-basis documentation. Keep it for as long as you own the property plus the US statute of limitations period.