If you've ever had a shipment held at customs without understanding exactly why, or if your customs broker gives you updates you don't quite understand, this article is for you. You don't need to become a foreign trade expert — but it's worth understanding what's happening with your cargo from the moment it leaves the warehouse to the moment it crosses the border.
Why understanding customs clearance makes you a better shipper
Customs clearance in Mexico is not a procedure you simply delegate to your broker and wait for results. It is a process where the information you provide — the value of the goods, their description, their origin, their tariff classification — directly determines how quickly and smoothly the shipment will cross.
When something goes wrong at customs, in most cases there is a documentation error at the root. And that error almost always comes from the shipper's side, not the broker's. Understanding the process allows you to prevent those errors before the truck leaves — which is exactly when they are still cheap to fix.
The parties involved in the process
Before discussing the steps, it's worth having a clear picture of who does what.
The customs broker is the professional authorized by the SAT to process the clearance of your goods. They hold a federal license and are the only party authorized to file the customs declaration (pedimento) with the customs authority. They are not an intermediary — they are the legal representative of your company before the customs authority for that operation.
The SAT is the authority that administers customs in Mexico and validates each pedimento. Its systems process the information, verify the tax compliance of the importer or exporter, and determine whether the cargo undergoes documentary or physical inspection.
The ANAM — Agencia Nacional de Aduanas de México — is the operational body that manages the fiscalized facilities and coordinates the physical inspection of goods when the system determines it is necessary.
You, as the shipper, are the one who provides all the base information. Without correct data from your side, none of the other parties can do their job properly.
The process step by step
Preparation of commercial documentation
Everything starts before the truck leaves. Your customs broker needs from you the commercial invoice with the true value of the goods, the packing list with weights and dimensions, the certificate of origin if applicable for the trade agreement you plan to use, and any special permits or certificates required for your type of product — sanitary, phytosanitary, Mexican official standards, among others.
This is the most important moment in the process and the one most underestimated. An incorrect piece of data here — a misspelled RFC for the receiver, a goods description that doesn't match what is physically in the cargo, a declared value that doesn't correspond to the invoice — can stop the operation hours or days later, when there is already a truck waiting at the border crossing.
Preparation and transmission of the pedimento
With that information, your customs broker prepares the pedimento — the fiscal and customs document that formalizes the operation before the SAT. The pedimento includes the tariff classification of your goods, the customs value, the origin, the customs regime under which it is declared, the applicable taxes, and the importer or exporter's data.
Once prepared, the pedimento is transmitted electronically to the SAT system — the SAAI — and the pedimento number is generated, which will identify that operation from that moment through the complete crossing.
Payment of duties and taxes
If the operation generates taxes — VAT, IECE, compensatory fees, or the Customs Processing Fee (DTA) — these are paid electronically before the goods enter the fiscal facility. The payment receipt is linked to the pedimento and is part of the documentation the authority will verify.
In export operations under USMCA with a valid certificate of origin, many product categories export at zero duty to the American market — but that does not eliminate the clearance process in Mexico or the documentation requirements for exit.
Activation of the automated selection mechanism
Once the pedimento is paid and in the system, the automated selection mechanism is activated — the traffic light. This SAT system randomly determines whether the goods undergo documentary inspection, physical inspection, or simply pass with payment cleared. There is no public formula for knowing when the light will turn red — it is randomly designed by nature, although factors such as the importer's profile, type of goods, and the company's compliance history influence the probability.
Green light means the goods can pass without further inspection. This is the ideal scenario and the most frequent for operators with a good compliance track record.
Orange light implies documentary inspection — a government verifier reviews whether the submitted documentation is correct and sufficient. There is no physical inspection of the cargo.
Red light triggers physical inspection. The goods are moved to an inspection area where ANAM personnel open, inspect, and cross-check the cargo against what was declared in the pedimento. This is the scenario that consumes the most time and has the greatest impact on dwell time.
Carriers certified under C-TPAT and companies with OEA status have access to preferential lanes and a lower risk profile that significantly reduces the probability of a red light. It doesn't eliminate it — but it reduces it.
Release and crossing
Once the inspection process concludes — documentary or physical — and there are no observations, the pedimento is released and the goods can leave the fiscal facility for their destination. In export operations to the U.S., this is the point where the clearance responsibility in Mexico ends and the entry process on the American side begins with the importer's customs broker.
Clearance in the U.S.
For Mexican exports to the United States, the entry process on the American side falls under the regulation of CBP and requires a customs broker with an American license. The base documents are the Bill of Lading, the commercial invoice, the packing list, and the USMCA certificate of origin if applicable. The process is analogous to the Mexican one — electronic transmission, document verification, possibility of physical inspection — with its own regulatory particularities.
The errors that delay clearance the most
There are errors that appear with disproportionate frequency in customs clearance operations in Mexico. Most are preventable with verification before the truck leaves.
A misspelled RFC for the receiver or importer is one of the most frequent and one of the most time-consuming to resolve once the unit is already in transit. A goods description that doesn't exactly match what the pedimento states — whether due to an imprecise translation, a commercial name that differs from the technical one, or an omission of relevant characteristics — is another recurring cause of holds. The Carta Porte with errors or not properly stamped under complement 3.1 can generate observations not only at customs but at any SAT checkpoint during transit. And the lack of prior permits for regulated goods — COFEPRIS, SENASICA, Secretaría de Economía — is the most costly error because there is no quick fix once the cargo is already in the facility.
What you can control and what you can't
Customs clearance has a part that depends entirely on you — the quality and accuracy of the information you give your broker — and a part you cannot control, such as the traffic light or the authority's processing time on high-demand days.
The most effective strategy is to focus all your attention on what you can control: flawless documentation, correct declared value, tariff classification verified with your broker before the first operation with a new product, and prior permits managed with sufficient lead time.
What you cannot control is best managed with a carrier that has real crossing experience, knows the timing of each customs facility at different hours, and has protocols in place for when the process takes longer than expected.
At Control Terrestre, we support every crossing operation with knowledge of the customs process on both sides of the border — because the difference between a smooth crossing and one that stalls for hours is almost always in the preparation details. Request a quote or subscribe to our newsletter to receive practical content on logistics and foreign trade every week.
