Mexico's Customs Law 2026: What importers, exporters, and customs brokers need to know

Effective January 1, 2026, Mexico’s Ley Aduanera (Customs Law) has dramatically increased documentation requirements for anyone importing or exporting through Mexico. If you move goods through Mexico, the increased documentation requirements can become a compliance risk if you’re not set up to both collect and verify the validity of documents.

The new reform introduced expanded electronic documentation, formalized Know Your Customer (KYC) requirements for customs brokers, and expanded shared liability between importers and their agents. For a single shipment, that can mean collecting and validating multiple supporting documents in addition to the customs declaration itself. Meanwhile, customs brokerages are now required to maintain current, verified identification files for every client. 

If you’re wondering how to handle these new requirements, this guide explains what the law requires, who is affected, what the penalties are, and what your team needs to do to comply.

Key translations to know for Mexico’s Customs Law in 2026

• El Servicio de Administración Tributaria (SAT): the Mexican Tax Administration Service 

• Agentes Aduanales: Customs broker

• Embargo precautorio: Precautionary seizure

• Pedimento: Customs declaration

• Agencia Nacional de Aduanas de México (ANAM): National Customs Agency of Mexico

• Código Fiscal de la Federación: Federal Fiscal Code

• Despacho aduanero: Customs clearance

• Responsabilidad solidaria: Jointly and severally liable

• Constancia de Situación Fiscal: Tax Status Certificate

• Acta Constitutiva: Articles of Incorporation

• Comprobante de Domicilio: Proof of Address

• Encargo Conferido: Letter of Authorization

• Comprobante Fiscal Digital por Internet (CFDI): Digital tax receipt

• Reglas Generales de Comercio Exterior: General Rules for Foreign Trade

What is Mexico's Customs Law 2026 (Ley Aduanera)?

Mexico's Ley Aduanera is the federal law governing all customs activity in Mexico. It covers the import and export of goods, customs clearance (despacho aduanero), and every party involved in Mexico’s international trade operations. 

Published in the Official Journal of the Federation (DOF/Diario Oficial de la Federación) on November 19, 2025, the law is administered by the Mexican Tax Administration Service (SAT/Servicio de Administración Tributaria) and the National Customs Agency of Mexico (ANAM/Agencia Nacional de Aduanas de México). 

Who does Mexico's 2026 customs reform impact?

The 2026 reform affects every party involved in moving goods into Mexico by expanding compliance responsibilities across the entire supply chain. 

Here’s a quick overview of who the law applies to and how it impacts them:

Four new changes to the Ley Aduanera 2026

It can be overwhelming to keep up with all the specific changes that apply to you, but there are four main changes to the 2026 reform that everyone in the Mexican trade industry should know:

1. Electronic documentation standards: An expansion of records you must collect, maintain, and produce

2. Client identity documentation: New KYC requirements for customs agencies or brokers to compile documentation verifying their clients’ identities

3. Expanded liability rules: Shared liability rules between importers and customs brokers 

4. Stronger penalties and enforcement: New triggers for administrative fines and criminal penalties 

We’ll discuss four of the most important changes to the law as they relate to expanded document requirements in greater detail.

1. Mandatory comprehensive electronic file (Expediente Electrónico) for every transaction

Every customs transaction (pedimento) must be backed by a documented electronic file called the Expediente Electrónico. It contains documentation that proves how you financed and executed each shipment transaction. 

This Expediente Electrónico isn’t a new filing for customs. The requirement to maintain and produce this electronic file on demand during an SAT or ANAM audit has existed since 2018. Companies were already required to retain key documents like the customs declaration (pedimento), compliance standard certificates (NOM/Norma Oficial Mexicana), and transport records.

What’s new is that the 2026 Ley Aduanera reform introduced eight new categories of documentation for the electronic file. We’ve mapped out specific documents your team must collect and maintain for each new category.

Who does the Expediente Electrónico apply to?

If you’re a broker, agency, importer, exporter, or a proxy, the new electronic file requirements apply to you. Under the General Rules of Foreign Trade (Reglas Generales De Comercio Exterior): 

• You must retain this electronic file for at least five years from the tax return filing date (or when it should have been filed)

• You’ll need to submit the file using electronic signature technology, or e.firma

As an example, let’s say your company supports 500 customs transactions annually. You’ll need to maintain 500 electronic files containing thousands of documents on an ongoing basis.

What are the CFDI and Carta Porte?

While not required for the Expediente Electrónico specifically, two additional documents are critical for compliance if you transport any goods within Mexico:

• CFDI (Comprobante Fiscal Digital por Internet) is Mexico's official electronic tax invoice. It serves as the legal proof of a transaction and must be transmitted in real time to the government.

• Carta Porte is a supplement added to the CFDI when goods are being transported. It shows legal proof that the goods in transport are properly documented.

The Carta Porte is separate from the electronic file requirement, but it’s used to prove that you’re properly documenting the authorization of transported goods within Mexico.

Even though it’s not formally a part of the Expediente Electrónico, you should retain the CFDI and Carta Porte for the same five-year period in your electronic file for audit and compliance purposes. 

2. Customs brokers must formally verify every client’s identity (Expediente de identificación del cliente)

If you’re a customs broker or a customs agency, you’re now legally required to fully identify (plenamente identificados) every client you work with. Before processing any customs operation, customs brokers and agencies must verify every clients’ identities, operational capacity, ties to taxpayer blacklists, and compliance history. 

Each client must have a documented identification file called the Expediente de identificación del Cliente, including:

• Current tax status certificate (Constancia de Situación Fiscal): Confirmation of the clients active registration with SAT and current on tax obligations

• Articles of incorporation (Acta Constitutiva): Documentation of the client's legal existence and corporate structure

• Proof of address (Comprobante de Domicilio): The physical business location

• Infrastructure documentation: Photographs, lease agreements, or property records demonstrating physical and operational capacity proportional to declared trade volume

• Legal representative (Representación Legal): Documentation confirming the person acting on behalf of the company is authorized to do so

• Letter of authorization (Encargo Conferido): A letter authorizing the customs broker to act on the client's behalf for customs operations

• Evidence of financial capacity: Bank statements or financial records showing the client can fund their declared operations

• Sworn client declaration: A statement made under oath confirming the truthfulness of all information provided

• SAT’s Article 69-B blacklist check: Confirmation that the client does not appear on SAT's blacklist list of taxpayers flagged for issuing invoices for non-existent operations, or a lack of assets, personnel, or infrastructure

For example, let’s say you oversee a brokerage managing 80 active accounts. Under Ley Aduanera’s new KYC rule, you now need to maintain individual client files for all 80 accounts. That includes tracking document validity, fiscal status, and blacklist standing continuously. If a client has a lapsed tax status or another client is on the taxpayer blacklist, both you and the client are responsible for catching that.

The stakes are pretty high, especially if you’re a customs broker. If you process a transaction using client data that turns out to be false or nonexistent, you might face permanent patent cancellation. This applies whether or not you knew the data was false or forgot to verify the client’s documents. 

That's why simply collecting documents isn't enough. You need to verify that the data in those documents is accurate, current, and matches what your client claims.

3. Shared liability between importers and customs brokers

One of the most important updates in the 2026 Mexico customs law reform is how importers and customs brokers share liability. Importers, customs agents (agentes aduanales), and customs agencies (agencias aduanales) can now be held jointly and severally liable (responsabilidad solidaria) for unpaid duties, taxes, and compensatory quotas (cuotas compensatorias). 

This means that SAT can pursue either party for the full amount owed, not just the party that made the mistake. You’ll share financial liability as a customs broker or an importer. If you’re a customs broker and the importer provides inaccurate information or fails to pay taxes, you may still be held responsible for the unpaid amount. And vice versa. 

There are only two exceptions to these rules: 

• Administrative fines are not shared. These fines only apply to the party that committed the violation.

• Transport-related infractions fall on the transport company owners or operators, not the customs broker or the importer.

4. Steeper penalties for non-compliance with the Ley Aduanera

Ley Aduanera has always enforced penalties, but the 2026 reform adds new triggers for how violations can escalate under the Federal Tax Code (CFF/Código Fiscal de la Federación). 

We’ve outlined the penalties below: 

These enhanced penalties matter because you can be prosecuted for smuggling-related offenses for a simple operational or documentation mistake. And because of the shared liability rules, both importers and customs brokers need to be aware of these costly financial and legal penalties. 

How to comply with Mexico's Ley Aduanera requirements in five steps

Expanding documentation requirements comes with increased operational burden on your team, especially if you’re collecting documents manually. More documentation also opens the door for more forged, tampered, or recycled documents to enter your files undetected.

If your company processes hundreds or thousands of customs transactions annually, manually collecting documents and verifying their validity isn’t realistic at scale. Follow these five steps to help you adapt to these new requirements:

1. Centralize and automate document collection and storage: Avoid relying on email or messaging apps to collect documents. Use a structured intake system that automatically links each document to the right client file or transaction record.

2. Automate document expiry tracking: Many documents like the Tax Status Certificate (Constancia de Situación Fiscal) have defined validity periods. Set up automated workflows that flag document expirations and send renewal reminders early.

3. Verify documents after collecting them: You need to verify all your documents to avoid potential fines or worse, like permanent patent cancellation. Use tools that can automatically check authenticity markers, validate digital signatures like the e.firma signatures, verify QR codes on tax documents, and flag signs of document tampering or inconsistencies.

4. Build an audit trail from day one: Track when each document was received, who submitted it, and what verification checks were performed to create a compliant audit trail.

5. Prepare for regulatory changes: SAT's implementing rules (Reglas Generales de Comercio Exterior) update annually. Build flexible compliance workflows so you can add new document requirements or adjust validation rules easily. 

How Persona can help

If preparing a complete, audit-ready Expediente Electrónico feels difficult to scale, you’re not alone. The 2026 reform expands documentation requirements and introduces a new level of verification, traceability, and ongoing maintenance that can get overwhelming. 

At Persona, we help companies operationalize these requirements. Our Document AI product automates information collection across the compliance documents now required under the 2026 Ley Aduanera reform. In 2025, we helped companies like Twilio, Wealthsimple, Travelex, and DolarApp process millions of supplemental documents. 

Instead of chasing documents across email and spreadsheets, you can use Document AI to:

• Automatically extract document data

• Cross-check for inconsistencies

• Flag signs of tampering before you submit your documents for an SAT or ANAM audit

As SAT rules evolve, you can configure Persona’s workflows to adapt quickly. And with Enhanced Fraud Detection, Document AI can also help prevent document tampering, forgeries, generative AI documents, and more, even as you collect more documents.

If you’re evaluating how to adapt your current process, we can walk you through how other companies are approaching document collection, verification, and audit readiness.

Talk to our team to see how Persona’s identity infrastructure supports Ley Aduanera compliance workflows in practice.