This guide is for importers, exporters, customs brokers and U.S. companies with goods in Mexico that have received a fine or a tax assessment (crédito fiscal) from Mexican customs or the SAT (Mexican tax authority). The short answer: you have thirty business days, counted from the date service takes effect, to pay or to challenge it through one of two routes: an administrative appeal (recurso de revocación) filed with the authority itself, or an annulment suit (juicio de nulidad) before the Federal Court of Administrative Justice. Filing a challenge does not stop collection on its own: the amount must also be secured with a guarantee. If the goods are still seized, start with the guide on the PAMA and customs seizure.
Where a foreign trade assessment comes from
It usually comes from a PAMA resolution, from a notice of facts or omissions (Article 152, Mexican Customs Law), from a post-clearance review of value, origin, tariff classification or permits, or from a fine for errors in the customs entry (pedimento) or its documents.
The thirty-day deadline: when it starts to run
Service takes effect on the business day after it is made (Article 135, Federal Tax Code). In the buzón tributario (the SAT electronic tax mailbox), a document that is not opened within three days is deemed served on the fourth (Article 134): the clock runs even if nobody opened it. Saturdays, Sundays and statutory non-business days are not counted.
The Customs Law reduces the fine by 20% if it is paid within thirty days after service (Article 199, section II), though not in every case. Whether to pay or to challenge is best decided with the documents reviewed: the first step is to have counsel look at the full resolution and the record of service.
Administrative appeal or annulment suit
- Administrative appeal (recurso de revocación): filed with the tax authority within thirty days after service takes effect (Article 121, Federal Tax Code). The authority must decide within three months; if it does not, the act is deemed confirmed (Article 131).
- Annulment suit (juicio contencioso administrativo): filed with the Federal Court of Administrative Justice (Tribunal Federal de Justicia Administrativa), also within thirty days after service takes effect (Article 13, Federal Law of Contentious Administrative Procedure).
Does a challenge stop collection? Securing the tax interest (garantía del interés fiscal)
Not on its own. The assessment must be paid or secured within thirty days after service takes effect (Article 65), and during that period the authority cannot start collection (Article 144). If by the end of it the challenge and the guarantee have not been shown, the authority may open the administrative enforcement procedure, which includes attaching assets and bank accounts.
The 2026 change: filing an administrative appeal no longer excuses a company from posting a guarantee. For appeals filed on or after January 1, 2026, the 2026 Federal Revenue Law allows the guarantee to be posted within six months after the appeal is filed.
What happens if the deadline passes
A filing made one day late is dismissed and the assessment becomes final. What is at stake is the amount of the assessment and, if collection begins, the company's assets and bank accounts. That is why the legal review is done at the start of the period, not at the end.
How we help
Mariela Cárdenas, LL.M., attorney admitted in Mexico, practices from the Nuevo Laredo, Mexico office and personally handles the administrative appeal and the suit before the Federal Court of Administrative Justice. Companies with recurring operations can rely on the legal department in Mexico.
Frequently asked questions
How long do we have to challenge a Mexican customs fine?
Thirty business days, counted from the day after service takes effect, for both the administrative appeal and the annulment suit.
Is the administrative appeal required before going to court?
No. It is optional (Article 203, Customs Law). The choice depends on the type of argument, the evidence available and the cost of keeping the guarantee in place for as long as each route takes.
Does filing a challenge stop collection?
Not on its own. Collection is suspended when the tax interest is also secured. For an administrative appeal filed in 2026 there is a six-month period to post the guarantee.
What happens if we neither pay nor challenge within thirty days?
The assessment becomes final and the authority can collect it through the administrative enforcement procedure, with surcharges and enforcement costs.
General information, updated October 2026. It does not replace legal advice for a specific case.
Request a first review
Send us the resolution and the record of service so we can review the case and the time you have left: Schedule a consultation, mariela@cardenaslegal.mx or +52 (867) 187 0075.