You sold your Puerto Vallarta condo for a healthy profit — congratulations. Now the notario hands you a closing statement with a line called ISR that quietly takes a five- or even six-figure bite out of your proceeds. That line is Mexico's capital gains tax, and how much you pay is decided long before closing day. Understanding it early is the difference between keeping your gain and handing a chunk of it to the tax authority.
What ISR on a property sale actually is
When you sell real estate in Mexico, the seller pays Impuesto Sobre la Renta (ISR) — income tax on the gain. It is not a flat number. It is calculated on the difference between your legally documented acquisition value and your sale value, minus certain deductible costs, and it is withheld and paid by the notario público at closing. That last point matters: the tax is settled at the notary's office as part of the deed, so there is no "sorting it out later." Whatever the calculation says on closing day is what comes out of your money.
How the gain is calculated — and why your paperwork decides it
The taxable gain is roughly your sale price minus your indexed acquisition cost minus documented improvements and allowable expenses. Two words in there do most of the damage: documented and indexed.
"Documented" means the tax authority only recognizes what you can prove with proper facturas (official invoices) and a deed that states the real purchase price. If your original purchase deed under-declared the price to save on acquisition tax — a common and dangerous shortcut — your paper cost is now artificially low, and your taxable gain is artificially high. Buyers who saved a little on the way in often pay for it many times over on the way out.
"Indexed" is the one piece of good news: your acquisition cost is adjusted for inflation over the years you owned the property, which legitimately lowers the gain. Renovations, the notary and acquisition costs you paid when buying, and real-estate commissions can also be deducted — but only when they are backed by facturas issued to you. Keeping those invoices from the day you buy is the single most valuable tax habit a foreign owner can build.
The primary-residence exemption — the big one, with strict conditions
Mexican law offers a generous exemption when you sell your principal residence, which can eliminate the ISR entirely up to a substantial cap. It sounds simple, but foreigners are the most likely to lose it on a technicality, because it requires you to prove the property was your home. That usually means residency status plus utility bills, bank statements or official ID showing the property's address in your name, generally for the required period before the sale.
Tourists who own a rental and drop in a few weeks a year rarely qualify — and assuming you do, without checking the proof beforehand, is how sellers get an unwelcome surprise at the notary's desk. The exemption can also only be used once within a set window, so timing a second sale matters. This is exactly the kind of thing to confirm with a professional tax advisor before you list, not after you have a buyer.
Fideicomiso, corporations and non-residents
How you hold the property changes the tax picture. If you own through a fideicomiso, the sale is still treated as your sale for ISR purposes — the trust is a holding structure, not a tax shelter. If you hold through a Mexican corporation, the gain is taxed at the corporate level under different rules, and the exemption for a principal residence generally does not apply. And if you are a non-resident for tax purposes, the notario may apply a withholding on the gross sale price instead of the net gain unless you provide the documentation to be taxed on the actual profit. Each path has a very different bottom line, which is why the structure you choose when buying deserves tax advice, not just real-estate advice.
How to protect your profit before you sell
By the time you are at the closing table, most of your tax outcome is already locked in. The moves that save real money happen earlier: buy with the full price properly declared on the deed, keep every factura for renovations and costs, confirm whether you qualify for the residence exemption while you still have time to meet its conditions, and get a written ISR estimate before you accept an offer so there are no surprises. A short consultation early can be worth many times its cost, and it pairs naturally with getting your closing handled properly so the whole sale runs clean.
Frequently Asked Questions
There is no flat rate — ISR is calculated on your gain (sale price minus your inflation-indexed, documented acquisition cost and allowable expenses), and the notario withholds it at closing. Because the number depends heavily on your paperwork, we recommend a written estimate before you accept an offer so there are no surprises on closing day.
You may qualify for a substantial exemption if the property was genuinely your principal residence and you can prove it with residency and address documentation for the required period. Foreigners lose it most often on a technicality, so confirm you meet the conditions before you list, not after you have a buyer.
ISR is based on the gain over your documented acquisition value. If your original deed under-declared the price to save on acquisition tax, your paper cost is artificially low and your taxable gain is artificially high — meaning you can pay far more now than you saved back then.
The trust is a holding structure, not a tax shelter — the sale is still treated as your sale for ISR. How you hold the property (trust, corporation, or as a non-resident) does change the calculation, however, which is why the structure deserves tax advice when you buy as well as when you sell.
Every factura (official invoice) for renovations, the notary and acquisition costs you paid when buying, and real-estate commissions — all issued in your name. These are deductible only when properly documented, so keeping them from the day you buy is the single most valuable tax habit a foreign owner can build.
Know your tax before you sell
Do not let the notary's ISR line be a surprise. We calculate your capital gains exposure in advance, confirm which exemptions and deductions you can legally claim, and structure your sale to keep more of your gain in your pocket.
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