An IMMEX program allows a company to import inputs, machinery and equipment under a temporary regime without paying import duty or VAT, provided the goods are transformed and returned abroad. It is a substantial benefit, and like every benefit of its kind, it comes with a trade-off.
The trade-off is documentary: being able to prove at any moment, item by item, that everything imported temporarily was returned, changed regime, or is still within its authorized time limit. The system that supports that proof is Annex 24.
What it actually is
Annex 24 is the annex to Mexico’s General Foreign Trade Rules that defines the mandatory minimum content of the automated inventory control system every company holding an IMMEX program must maintain.
Two points that are often confused:
- It is not a report you file. It is a system you must have running and be able to show on request.
- It is not your ERP. It can be fed by your ERP, but a standard ERP does not satisfy Annex 24 without specific configuration. The difference is that Annex 24 reasons in customs terms — pedimentos, tariff classifications, regimes, discharges — not in accounting terms.
What it must contain
In practical terms, the system has to answer four questions about any input, on any date:
- What is it? A materials catalog with description, tariff classification, unit of measure and its equivalence to the tariff unit.
- How did it come in? Receipts linked to the temporary import pedimento that covered them: number, date, quantity, value.
- How did it leave? Issues by return abroad, change of regime to definitive, virtual transfer to another IMMEX company, or documented destruction and scrap.
- What is left? Current balances by material, with the permanence deadline for each lot.
The logic of the discharge
The core mechanism is the discharge: when you export finished goods, the return pedimento has to deduct from your balances the inputs that product consumed.
That deduction is computed from your bill of materials — the BOM — which translates “I exported 500 units of model X” into “I consumed this much steel, this much cable and these connectors, imported under these pedimentos”.
This is where nearly everything breaks. If the BOM does not reflect real consumption, if it does not account for process scrap, or if nobody updated it when the product design changed, the discharge is wrong at the source and the error compounds with every export.
Deadlines matter as much as balances
Temporarily imported goods carry a maximum permanence period in the country. Inputs have a set limit depending on the type of goods and program; machinery and equipment can generally stay while the program remains in force. Confirm the limit applicable to your case, because it is not a single figure for everything.
An input that passes its deadline without being returned or changing regime is no longer covered. At that moment it becomes undeclared definitive-import merchandise, carrying the duties and taxes that went unpaid plus adjustments and surcharges.
That is why the most useful report your system can produce is not the balance report but the balances approaching expiry report.
VAT/IEPS certification and Annex 31
If you also hold the VAT and IEPS certification — the one that allows applying a credit instead of paying VAT on temporary imports — Annex 24 stops being an administrative obligation and becomes the basis of a direct financial benefit.
Control of those credits and guarantees lives in a separate system, and the certification is renewed subject to your continuing to meet the requirements, inventory control among them. Losing it is not a formality: it means starting to disburse VAT on every temporary import.
What breaks first
In order of frequency:
- Outdated BOM. The product changed, the system did not. It is the root cause of most discrepancies.
- Undocumented scrap and waste. Material was consumed, destroyed or discarded, but there is no record and no customs destination for it.
- Incomplete virtual transfers. A transfer between IMMEX companies requires matching pedimentos on both sides. If only one was filed, the balance is left hanging.
- Negative balances. The system discharges more than it recorded as received. An unmistakable sign that receipts are not being captured in full.
- Amendments not reflected. A pedimento was amended and inventory kept the old figure.
- Unrecorded regime changes. The input was nationalized, but the system still shows it as temporary.
What to review every quarter
- Reconcile system balances against physical inventory.
- List and act on lots expiring within the next 90 days.
- Confirm there are no negative balances.
- Verify the BOM matches the product currently being manufactured.
- Check that all scrap and waste has a record and a documented destination.
- Reconcile virtual transfers still missing their matching pedimento.
- Confirm the period’s amendments were reflected in inventory.
A discrepancy caught in a quarterly review is an adjustment. The same discrepancy caught during an audit is a tax assessment.
What is at stake
An inventory control that does not reconcile can lead to an assessment of duties on goods that cannot be evidenced as returned, to loss of the VAT/IEPS certification, and to suspension of the IMMEX program. Suspension means the operation can no longer import temporarily — it stops.
It is worth seeing from the other side: a well-kept Annex 24 is what makes the IMMEX benefit defensible. Without it, the benefit exists right up until someone reviews it.
Related
If your operation combines IMMEX with warehousing, a strategic bonded facility changes where and under which regime goods are held. And if you import inputs that do not classify obviously, review Rule Eight.
At TradeWay
We provide foreign trade consulting for operations running promotion programs, and we coordinate the clearance, transport and bonded warehousing that feed your inventory control, through a single point of contact. If your Annex 24 does not reconcile or you want it reviewed before somebody else reviews it, contact us.
