Annex 24 (Anexo 24) in Mexico: What Manufacturers Need to Know

Annex 24 usually comes up at one of two moments. You are weighing Mexico, and an advisor lists it among the rules your operation would live under. Or you already run a plant there, and an audit, a provider change or a question from your trade team has put the inventory record on your desk.

Annex 24 (Anexo 24) sets out the minimum information Mexico requires in an automated customs inventory system. Every company with an IMMEX program has to keep that system and use it to account for its temporary imports. IMMEX is the Mexican authorization that lets a manufacturer bring in materials and equipment temporarily for export production.

The record ties together what entered Mexico, what production used, what went back out and what is still open. Using a part in production does not, on its own, close out its import.

Whether you are planning a plant in Mexico or reviewing one you already run, the same three questions matter. What does the record have to contain, how does it stay current and who is responsible for it?

What Annex 24 requires for IMMEX inventory control

Mexico’s Customs Law and the IMMEX Decree create the duty to keep the system. The Customs Law says it must be automated, kept current at all times and available to customs authorities. Annex 24 lists what it must contain, and software vendors build their tools to meet it.

For most IMMEX companies, Part A of the annex sorts that information into three groups:

• Catalogs: company details, materials and finished products.
• Customs modules: temporary imports, materials used and fixed assets such as machinery, plus returns and other permitted exits.
• Reports: entries, exits, open balances and materials used.

Part C adds more for certified companies. It covers manufacturers with IVA/IEPS certification, which gives a credit for the VAT on eligible temporary imports, and some categories of Authorized Economic Operator (OEA), Mexico’s trusted-trader certification. They must update their system within 48 hours after customs clearance is completed and give SAT’s foreign-trade audit unit a login, so the authority can check the system online.

How long IMMEX temporary imports can stay in Mexico

The record also has to show that each import stayed within its time limit. The common limits are below. The goods, the transaction and the company’s own authorizations can change the time limit that applies.

A discharge reduces the open balance recorded against a temporary import. Annex 24 works first in, first out: each discharge comes off the oldest open import of that material. Scrap needs its own documented customs treatment too. Logging it in the system does not close out the import.

IVA/IEPS certification has its own eligibility rules, and holding it does not lengthen these time limits.

What happens when the customs record and the plant floor disagree

Because the record has to show all of that, a difference between it and the physical count needs an explanation. What follows depends on what caused the difference and which rule was broken.

Not keeping the required inventory system is an offense of its own. It carries a fine of MXN 27,070 to 54,180 at 2026 amounts. The fine applies to that offense alone. It is not a price tag for every difference.

Where a breach leaves foreign-trade taxes unpaid, the Customs Law adds a fine of 130% to 150% of the taxes owed. Other breaches carry other penalties. Depending on the facts, problems with temporary imports can also lead to tax assessments or put the IMMEX program at risk.

Mexico’s IMMEX 4.0 initiative also includes plans to review whether program holders meet the requirements they already have. Its measures are at different stages, and the inventory rules described here apply today.

Why your part data decides whether the Annex 24 record holds

All of this rests on data. Your company supplies the facts the customs record is built on: part numbers, descriptions, values, origins and the bill of materials, or parts list, for each finished product.

When an engineering change alters those parts, or production creates scrap, the data your trade team works from has to be updated too. If it is not, the production count and the customs record drift apart. Regular reconciliation is how those differences come to light and get fixed.

Who keeps the Annex 24 record: your own program or a shelter

That leaves the practical question of who keeps the record. The answer depends on whether you hold your own IMMEX program or operate under a shelter provider’s program.

If you have your own Mexican company and IMMEX program, the record is your company’s job. You can run it in-house or hire a specialist, but someone has to keep the system current, sort out differences and help answer customs.

In a shelter arrangement, your imports come in under the provider’s IMMEX program, so the record is kept under that program. You supply accurate product and production data. Check what your agreement covers: who records the materials used, who reconciles the record and who answers customs when it asks questions.

Questions to ask if you already operate in Mexico

Four questions are worth putting to your team:

1. When was the customs record last reconciled with a physical count, and which differences are still open?
2. How do scrap and engineering changes reach your trade team, and how do you check the record was updated?
3. Which open imports are closest to their time limit for return or other customs treatment?
4. If you hold IVA/IEPS certification, how do you find and fix differences between the Annex 24 record and the Annex 30 accounts where SAT tracks that VAT credit?

How Tetakawi handles the Annex 24 record

Tetakawi has helped companies manufacture in Mexico since 1986. Today it helps manufacturers expand into Mexico through its Manufacturing Campus model and its shelter services. You run your own factory, and Tetakawi runs everything around it. Tetakawi is not a contract manufacturer.

You control production, process and quality.

A Campus adds established industrial space, shared infrastructure and an on-site support organization. That support covers four areas. Industrial Space is the building your plant runs in. Workforce covers recruiting, employment and payroll, while you direct the work. Logistics covers your imports and exports, including the Annex 24 record. Compliance covers the registrations, permits and standing your operation relies on.

In this shelter arrangement, your plant operates under the IMMEX program and registrations held on Tetakawi’s side of the arrangement. That is why the Annex 24 record sits there too. Here is how it is kept:

• Tetakawi builds the customs inventory record. Its import and export team uses its own trade system and the part data and bills of materials you supply. The team audits each load’s customs invoice against that record before the goods cross. A client portal shows shipment status and inventory.
• Tetakawi records the materials you use. The team posts what production uses from your bills of materials and updates the record with the changes you report.
• Tetakawi reconciles the record with you each month. The team compares it with what you declared. This check comes on top of the system updates the rules require.
• Tetakawi responds to customs audits. When customs audits a declaration under the program, the compliance team meets the auditor and answers questions through to the close.

Your team supplies accurate part data and reports engineering changes, scrap and cycle counts. The customs duties on your goods stay yours. See how Tetakawi’s import and export services support an operation on a Campus.