The Chief Justice of the Supreme Court of Justice of the Nation (SCJN), Hugo Aguilar Ortiz, will propose confirming that the Property Acquisition Tax (ISAI) established in Mexico City is unconstitutional and will seek to have it declared invalid.
This is the same criterion that, since 2024, has favored Cardinal Norberto Rivera Carrera, allowing the Mexico City government to refund him more than 1.3 million pesos for ISAI payments and other registration fees (Proceso, April 29, 2025).
Aguilar Ortiz will present the case on April 6 to the full Court for the resolution of amparo appeal 298/2025, filed by a woman who argued that the ISAI violates the principles of proportionality and progressivity enshrined in the Constitution.
In his draft opinion, the minister plans to declare that the ISAI (Property Acquisition Tax) established in the Mexico City Tax Code is indeed unconstitutional because its calculation can result in people with less economic capacity paying more than those with higher incomes, making it disproportionate.
“The property acquisition tax is a direct tax that levies assets, as it taxes the ability to pay demonstrated by the acquisition of real estate, based on its economic value,” the draft opinion states.
“The application of the tax rate demonstrates that progressivity is distorted by multiplying the amount exceeding the lower limit by the application percentage and adding the fixed fee, which results in a disproportionate tax burden. (…) The challenged regulation causes taxpayers with less ability to pay to pay, compared to those with greater ability, to pay a higher tax, even though the purpose of the tax is that the higher the value of the property, the higher the tax paid.”
Therefore, he will propose granting the plaintiff an injunction so that the Mexico City government returns the money she overpaid.
However, unlike the Norberto Rivera case, Justice Aguilar Ortiz anticipates that the Court will declare that this does not mean Mexico City residents will stop paying the ISAI (Property Acquisition Tax), but that the method of calculating it must be modified.
Therefore, he expects to order the Mexico City authorities to recalculate the ISAI using different thresholds so that the plaintiff receives a refund for the overpayment.
“If the declaration of unconstitutionality of the tax in question is based solely on the fact that its rate demonstrates a distortion of progressivity by multiplying the variable consisting of the excess over the lower limit by the variable related to the application percentage and adding the fixed fee variable, resulting in a disproportionate contribution and, therefore, a violation of the principle of tax proportionality, this circumstance does not, in itself, exclude the obligation to pay, which in this case is represented by the tax determined for properties located at the upper limit of the range immediately preceding the one that originally corresponds to the taxpayers,” it clarifies.
“For the purposes of calculating the tax in question, the property value will be set at the immediately preceding range corresponding to the taxpayer’s maximum value (upper limit), subtracting the lower limit. The resulting excess will be multiplied by the application factor for the excess over the lower limit, and the respective fixed fee will be added to the resulting amount, yielding the final result of the property acquisition tax payable. Therefore, the appealed judgment should be modified as specified above, so that the responsible authority reimburses the plaintiff the amount resulting from the excess paid as a result of calculating the property acquisition tax according to the rate declared unconstitutional.”
For the article to be declared unconstitutional and invalid, the Chief Justice of the Court requires the votes of five additional justices in the plenary session.
Source: proceso
