SCJN upholds SAT penalties for late tax filings: what changes for your defense (2026)

On March 2, 2026, the Supreme Court of Justice of the Nation (SCJN) ruled on a constitutional challenge that questioned the constitutionality of SAT penalties for filing tax returns late or not filing them electronically. The ruling is clear: these tax penalties are constitutional, definitively closing the debate on their legality.

This ruling strengthens the SAT's legal authority to penalize late filing of returns. There is no longer any doubt about the general validity of these penalties; therefore, the focus of legal defense must shift to how they are calculated and substantiated.

What did the SCJN say? Penalties with a range, not fixed amounts

The Court analyzed the design of the tax penalty system in legislation. According to Article 82, section I, subsection d) of the Federal Tax Code (CFF), it concluded that they do not violate fundamental rights because the law does not set a single penalty, but rather establishes a range (a minimum and a maximum). To apply the exact amount, the authority must evaluate:

• The severity of the non-compliance.
• The taxpayer's history and conduct (recidivism).
• The economic capacity of the offender.

For the SCJN, this flexible scheme is valid because it adapts to particular circumstances. However, this does not mean that every penalty applied by the SAT is correct.

How to challenge an SAT penalty after the Court's ruling

The Court clarified that the SAT has an undeniable obligation to justify and substantiate each penalty. It is no longer enough to simply state that a deadline "has expired" and issue the penalty; the authority must legally specify why it chose a particular amount within the legal range.

In practice, it is very common for the SAT to omit explaining how it determined the penalty. If this occurs, a court can annul the penalty due to lack of substantiation and justification.

With this ruling, tax compliance now gains greater relevance, and legal defense will focus on challenging its improper application under the following grounds:

• Lack of justification: The SAT does not clearly explain why it imposed a specific amount and not another.
• Special circumstances: Verifiable failures in the SAT's system, force majeure events, or natural disasters.
• First non-compliance: Argue that, in the absence of repeat offenses, the minimum penalty applies.
• Disproportionality: Demonstrate that the fine represents an excessive percentage relative to income.

However, these arguments are no longer based on the fine being unconstitutional — they are based on the fact that the fine was improperly applied.

Why the SAT detects non-compliance almost immediately

This ruling gains greater relevance in the current tax environment. Given that it's a virtually digitized ecosystem, the SAT's automated systems detect non-compliance and issue penalties for late filings almost immediately. In this model, timely and proper compliance is mandatory; there are no legal excuses for delays.

Consequences of not filing on time: beyond the fine

According to articles 81 and 82 of the Federal Tax Code (CFF), penalties for not filing returns range from $2,000 to $25,000 pesos for each undeclared obligation. If a prior demand is issued, the range increases from $2,000 to $50,000 pesos, and for not using electronic means, it ranges from $20,000 to $42,000 pesos.

However, the cost of non-compliance goes beyond the monetary penalty:

• Accrual of surcharges and interest.
• Loss of benefits: Possible revocation of installment payment authorizations.
• Restriction of Digital Seals (CSD): According to Art. 17-H Bis of the CFF, non-compliance can lead to the temporary restriction of issuing invoices (CFDI), paralyzing the company's commercial operations.
• Negative Compliance Opinion (Art. 32-D CFF): Affects the company's ability to enter into contracts with clients, participate in tenders, obtain bank financing, subsidies, or incentives, and carry out any tax procedure.

How to avoid SAT fines: voluntary disclosure (Art. 73 CFF)

If there is a delay, it is vital to file the declaration voluntarily as soon as possible. In accordance with Article 73 of the Federal Tax Code, no penalties will be imposed when tax obligations are met voluntarily, provided that:

• Before the non-compliance is discovered by the tax authorities.
• Before the authorities have issued an audit order or request.
• Within 10 days following the submission of the financial statement audit report to the SAT.

Prodecon reinforced this stance in 2026: the SAT cannot impose a fine if the taxpayer complies before being notified. Acting before any tax action is the most effective strategy.

Given the Supreme Court's support for the SAT, the best defense is prevention: establishing rigorous internal controls to ensure declarations are filed within legal deadlines and to avoid operational and financial contingencies. Nevertheless, if penalized, it remains vital to seek tax and legal advice to examine the validity and proper determination of the penalty, as well as the available means of defense.