Electronic file (Art. 36-A / 59): how to build and keep it

The electronic file is, in practice, your insurance in a SAT review. It is the set of documents that back each import operation and, integrated correctly, demonstrate that the goods entered the country in compliance. Mexico's Customs Law addresses it mainly in articles 36-A and 59. This guide explains what to include, how to organize it, and how long to keep it.

What it is and why it matters

It is not a single document, but a dossier per operation. When the authority reviews an import, it does not look at an isolated data point: it reconstructs the full history of the goods from the documents you were required to integrate and keep. If a piece is missing, the operation is exposed, even if the pedimento was properly filed.

What documents it usually includes

The exact content depends on the type of goods and the regime, but a solid file usually gathers:

• The pedimento and its attachments.
• The commercial invoice and the corresponding CFDI.
• The transport document (bill of lading, air waybill) and the packing list.
• The certificate of origin, when preferential tariff treatment applies.
• Permits, NOMs and non-tariff regulations required for that tariff code.
• Proof of value and of the commercial relationship (contracts, purchase orders, payments).

How long to keep it

The retention obligation is counted in years, not months, and usually extends for the period during which the authority retains its powers of review. As an operational reference, many importers adopt a five-year horizon to be safe. Keeping too much is rarely a problem; keeping too little is. Verify the applicable period for your case with your advisor.

How to build it without chaos

The most common mistake is leaving the file for last: gathering documents in a rush on clearance day, with files scattered across WhatsApp, email and local folders. A safer approach is to build the file as the operation progresses:

• Open the file when you place the purchase order, not when you reach customs.
• Attach each document as soon as it exists, with its date and owner.
• Check for gaps before each milestone, not after.

The role of digital traceability

A foreign-trade project management platform turns the file into a living process: each operation has its own space, documents are integrated as they arrive, and all parties —supplier, customs broker, forwarder— work on the same dossier. With AI, the system can also flag which documents are missing for a specific tariff code before the absence becomes a problem at customs.

That way, when a review comes, you reconstruct nothing: the file is already integrated, kept and ready to be demonstrated.