The sale of real estate in Mexico — its enajenación — may generate income tax (ISR) on the gain: broadly, the difference between the documented acquisition value, adjusted as the law allows, and the sale price, due at the time of sale.
By the time of the sale, the outcome is mostly already set.
What Shapes the Result
Four factors do most of the work: the seller’s tax-residency status, the acquisition value actually documented in the original deed, improvements documented as they were made, and any exemption for which the seller may qualify.
The Primary-Home Exemption
Mexican income tax law exempts the sale of a primary home when the conditions are met — tax residency among them. For a foreign national, residency is proved, not declared, and never assumed; the law sets a strict evidentiary standard. The exemption is not automatic.
Why Records Decide It
Acquisition values, improvement invoices (CFDI), and residency evidence are built over years, not produced at the closing table. The reductions and exemptions the law allows reach only the seller whose file already exists when the property is sold — never the one who goes looking for it afterward.
A disposition planned in advance protects the gain; one improvised at the notary’s desk rarely does.