Customs Law Reform: Changes to Precautionary Seizure and Undervaluation

On October 23, 2026 the Official Gazette of the Federation (DOF) published the Decree amending and adding various provisions of the Customs Law with the goal of strengthening foreign trade enforcement.

The reform changes key rules on precautionary seizure the substitution of guarantees and the presumptions of infringement related to undervaluation of goods. Below are the main changes.

Ex officio audit powers (Article 144)

A second paragraph is added to section XII of Article 144 that empowers the customs authority to start its audit powers ex officio when the value declared in the customs entry is lower than the transaction value of identical or similar goods, determined under Articles 72 and 73 of the Customs Law.

Precautionary seizure without the 50% threshold (Article 151)

Section VII of Article 151 is amended: the authority will proceed with a precautionary seizure when the value declared in the customs entry is lower than the transaction value of identical or similar goods regardless of the difference.

Before the reform, seizure applied only when the declared value was lower by 50% or more unless the guarantee under Article 86-A had been provided. Now, the applicable percentages will be set in the rules issued by the authority under the transitional articles.

Return of goods and release of guarantees (Article 153)

The return procedure remains in place when the interested party proves the legal stay or possession of the goods, refutes the grounds for seizure or shows that the declared value was determined under the valuation methods. In those cases, the authority will resolve immediately, without penalties and returning the goods involved.

As a new feature, the authority will also release the guarantee or return the cash deposit provided under Article 154, according to the rules issued by the customs authorities.

Substitution of precautionary seizure (Article 154)

Within ten business days after notice of the start of the proceeding, interested parties may request substitution of the seizure in the cases of Article 151, section VII, provided the goods are not subject to estimated prices:

• Difference below 20%: cash deposit or deposit in customs guarantee accounts.
• Difference of 20% or more: cash deposit only.

Presumption of infringement for undervaluation (Article 177)

The undervaluation threshold to presume a customs infringement is reduced from 50% to 20% under the new rules. It applies when, during an audit, the authority finds that goods imported under a regime that allows duties to be determined without paying them were declared at a value 20% or more below that of identical or similar goods, and that their definitive importation would have resulted in unpaid foreign trade taxes and, where applicable, countervailing duties.

Fines for hydrocarbons and petroleum products (Article 185)

A second paragraph is added to sections I, II and III of Article 185. When infringements related to the transmission and submission of information, documentation and declarations under Article 184 involve hydrocarbons and petroleum products a fine of 50% to 100% of the commercial value of the goods will apply.

Effective date

The reform will take effect on January 1, 2027 under its transitional provisions. In addition, the authority must publish, no later than December 31, 2026 the rules establishing the goods subject to precautionary seizure under Article 151, section VII, and the applicable procedure. For other goods, those rules may set the value difference percentages that will determine whether seizure applies.

Recommendations

In light of these changes, we recommend:

• Review customs valuation methodologies to ensure that declared values are properly supported.
• Strengthen foreign trade files by verifying that customs entry information is consistent with supporting documentation.
• Identify transactions with potential undervaluation risks to prevent contingencies and reduce exposure to customs penalties.

At Baker Tilly Mexico, we are ready to support you in meeting your foreign trade obligations and reviewing your customs valuation processes.