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Which regime does this go under?
It is the question that gets asked last, usually by someone at the border with a truck waiting, and it is the question that should have been answered before the purchase order was issued. The regime you declare is not a filing category. It is the decision that sets whether you pay duty now or later or never, how long the goods can stay, who is allowed to touch them, what inventory system you must run, and what happens if any of that goes wrong.
Mexican law now says as much in its own words. As of the reform that took effect January 1, 2026, the Ley Aduanera carries a definition of régimen aduanero that did not exist before: the destination that, under Title Four of the Law, determines the legal treatment given to merchandise subject to clearance, control and oversight by the customs authorities, including the applicable obligations or restrictions and the acts and formalities inherent to it.
Read that definition slowly. It does not describe a form. It describes a body of obligations that attaches to your cargo the moment you choose.
This is the comparative guide to the six regimes, what each one actually costs and requires, and how operators choose between them.
The six, as the law lists them
Article 90 of the Ley Aduanera sets out six headings. Merchandise entering or leaving Mexican territory can be assigned to one of them, and only one at a time.
Definitivos. Import and export. The merchandise enters to stay, or leaves for good. Duties and other contributions are paid at entry, non-tariff regulations and restrictions are met at entry, and the customs relationship closes.
Temporales. Import and export, each with two branches. On the import side: to return abroad in the same state, or for elaboration, transformation or repair under a maquila or export program, which is where IMMEX lives. On the export side: to return to the country in the same state, or for elaboration, transformation or repair. The defining feature is a clock. The goods are in the country for a legally defined period and must leave, or change regime, before it runs out.
Depósito fiscal. The goods are stored in an almacén general de depósito (a general deposit warehouse authorized for the regime) with duties suspended, and are withdrawn against payment as they are needed, in whole or in part.
Tránsito de mercancías. Internal and international. The goods move under customs control between two points without being cleared at the point where they entered.
Elaboración, transformación o reparación en recinto fiscalizado. Manufacturing or repair carried out inside a bonded facility rather than at your own plant.
Recinto fiscalizado estratégico. A defined area, authorized under the Law, where merchandise can be handled, stored, held in custody, exhibited, sold, distributed, elaborated, transformed or repaired under a specific set of controls.
Six headings. That is the map most guides stop at. It is also the level at which almost nobody makes a bad decision, because at this level the regimes look obviously different from one another. The expensive mistakes happen one layer down.
The division that actually decides your exposure
Here is the split that matters more than the six headings, and it is not in Article 90 at all. It is in Article 2.
The Ley Aduanera defines programas de diferimiento de aranceles, duty deferral programs, as a specific set of regimes: temporary import for elaboration, transformation or repair under maquila or export programs, depósito fiscal, recinto fiscalizado estratégico, and elaboration, transformation or repair in recinto fiscalizado.
Four of the six regimes are duty deferral programs. That classification is not a label. It is the trigger for a set of consequences that follow the goods for their entire life in Mexico. It also shapes the treatment of duties when finished goods are eventually exported to a USMCA partner, because the agreement limits the relief a deferral program can ultimately provide.
The 2026 reform changed the membership of that list. Recinto fiscalizado estratégico was brought inside it. An operation that chose RFE before the reform because of its handling flexibility is now running a duty deferral program, with everything that entails, whether or not anyone in the organization has taken note.
This is why "which regime" is a finance question wearing logistics clothing. Two regimes can look operationally identical for a given shipment and sit on opposite sides of the deferral line.
Choosing: the four questions that settle it
In practice the choice resolves through four questions, asked in this order.
What is the merchandise, and what happens to it here? Raw material entering a transformation process points toward temporary import under IMMEX or toward one of the recinto regimes. Finished goods that will be sold as-is in Mexico point toward definitivo or depósito fiscal. Goods in transit to a third country point toward tránsito.
How long will it stay? This is the question that eliminates options fastest. Temporary regimes carry legal return windows. Depósito fiscal does not impose the same clock but does impose storage economics. Definitivo has no clock because there is nothing to return.
Where will it end up? If the finished goods are destined for the United States or Canada under USMCA preference, the deferral treatment of the inputs becomes part of the calculation before the first import, not after the first export.
Who controls the premises? This is the question operators skip, and it is decisive. Temporary import under IMMEX means the transformation happens at your authorized facility. Elaboration in recinto fiscalizado means it happens inside someone else's bonded facility. Recinto fiscalizado estratégico means it happens in an authorized area whose operator carries obligations including inventory control, video surveillance, traceability and real-time monitoring linked to the customs electronic system. Same physical activity, three different regimes, three different sets of people responsible when an auditor arrives.
Q: What is the most common regime mistake you see, and is it usually caught?
Daniel Sánchez, Customs General Manager, Joffroy
A: The most common one is not choosing the wrong regime. It is choosing a correct regime and then operating it as if it were a different one. A company imports temporarily under IMMEX, which is right for its process, and then treats the inventory the way it would treat merchandise imported definitively, because internally nobody distinguishes between the two. The regime was correct on the pedimento and wrong in the warehouse. It is usually caught, but it is caught by the discrepancy between what the system says is on hand and what the return obligation says should have left. By then the correction is a rectification and, depending on the timing, contributions with surcharges.
What each regime asks of you after clearance
The regime does not end at the border. Each one carries an ongoing obligation, and this is where operations that chose well still get into trouble.
A temporary import under IMMEX obligates automated inventory control under Anexo 24, tracked entry by entry against discharge, with every unit accounted for before its return window closes. A definitivo obligates nothing further once cleared, which is exactly why it is the right answer more often than the instinct to defer duties suggests.
Depósito fiscal obligates coordination with the warehouse, because the entity that issues the carta de cupo electrónica and files the notices is not you, and a compliance failure on their side becomes a capacity failure on yours. The recinto regimes obligate you to a facility whose authorization depends on technology and controls outside your direct management.
Consider a common corridor profile. A manufacturer setting up in the Bajío needs to bring in production equipment and, separately, a steady flow of components. The instinct is to run everything through one regime for simplicity. But the equipment is fixed assets that will stay for years, while the components are inputs that will leave inside finished goods within months. Running both temporarily under the same program means the equipment sits in an inventory system built to track consumption against a return deadline it will never meet in the ordinary way. Running the equipment definitivo costs duty at entry and eliminates a control obligation that would otherwise persist for the life of the asset. Neither answer is universally right. The point is that they are two different decisions, and treating them as one is how a clean IMMEX becomes a reconciliation problem in year two.
When the regime needs to change
Regimes are not always permanent. The law contemplates change of regime, and it is a legitimate tool rather than an admission of error. Merchandise imported temporarily can, subject to the applicable conditions, be changed to definitivo with the contributions paid. Goods destroyed by accident under a temporary regime, depósito fiscal, tránsito or recinto fiscalizado estratégico do not trigger payment of foreign trade taxes or countervailing duties, though the residue stays under the original regime unless the authority authorizes otherwise.
The practical test for whether you should be looking at a change is simple. If merchandise is sitting under a temporary regime with no realistic path to leaving inside its window, the change of regime is available now and will not be available later at the same cost. Waiting does not preserve the option. It converts it into a liability with surcharges attached.
Across more than 190,000 customs operations a year at 39 or more ports, the operations with the cleanest customs profiles are rarely the ones using the most sophisticated regime. They are the ones whose declared regime matches what the business actually does with the goods, consistently, over years.
The right regime is the one you can still defend eighteen months from now, when the person who chose it has moved on and all that remains is the record.
Talk to a Joffroy expert about a regime review for a new operation or a change of regime on inventory that is running against its window.
TRADE. UNDER CONTROL.
