IMMEX and the Maquiladora Program: A Cross-Border Manufacturing Guide

IMMEX is the Mexican government program that makes cross-border manufacturing at the San Diego and Otay Mesa border economically viable. It lets a Mexican plant bring in foreign raw materials, components, and machinery on a temporary basis, defer the taxes that would normally apply, and then export the finished goods. If you have ever wondered how a product can be assembled in Tijuana from US-made parts and shipped back into the United States without being taxed twice, IMMEX is the mechanism that answers the question.

This guide explains what IMMEX actually is, how the temporary import and duty deferral work, how components move south and finished goods move north, and what has to happen on the US side of the ledger to keep the whole cycle compliant. The program sits at the center of both a Mexican customs declaration (the pedimento) and a US customs entry, so getting it right means coordinating two customs regimes at once.

What IMMEX Is

IMMEX stands for Industria Manufacturera, Maquiladora y de Servicios de Exportación, which translates as Manufacturing, Maquiladora and Export Services Industry. It is a program administered by Mexico’s Secretaría de Economía (Ministry of Economy). The IMMEX Decree, published on November 1, 2006, consolidated two older programs, the Maquiladora program and the PITEX program, into a single legal framework. When people at the border say maquiladora and IMMEX, they are usually talking about the same modern program.

The core purpose is straightforward. IMMEX authorizes a company operating in Mexico to temporarily import goods that will be used to manufacture, transform, or repair merchandise, on the condition that the resulting product is exported. Because the goods are only passing through Mexico rather than being sold there, the program allows the importer to defer or avoid the taxes that a permanent import would trigger.

IMMEX is not automatic. A company must hold an authorized IMMEX registration tied to a specific facility and a specific scope of operations. That authorization carries obligations: the company has to maintain an automated inventory control system, prove that temporarily imported inputs were actually exported, and meet minimum export requirements. Losing track of those obligations is how a duty deferral turns into a tax assessment.

• IMMEX = Manufacturing, Maquiladora and Export Services Industry program
• Administered by Mexico’s Secretaría de Economía under the 2006 IMMEX Decree
• Consolidated the older Maquiladora and PITEX programs
• Grants temporary import treatment to goods used to make products for export

Temporary Import With Duty Deferral

The financial heart of IMMEX is temporary importation. A permanent (definitive) import into Mexico normally owes the general import tax, known as the IGI (Impuesto General de Importación), plus value added tax, the IVA (Impuesto al Valor Agregado), currently 16 percent, plus any applicable countervailing duties. Under IMMEX, goods brought in temporarily to be processed and re-exported can move without paying the IGI, because the product is destined to leave Mexico rather than enter its domestic market.

Value added tax is where many companies get tripped up. A 2014 tax reform changed the treatment of IVA on temporary imports. Since that reform, temporarily imported goods are technically subject to the 16 percent IVA unless the company holds an IVA and IEPS Certification (Certificación en materia de IVA e IEPS) issued by Mexico’s tax authority, the SAT. A certified company receives a fiscal credit equal to the tax, which effectively neutralizes it. The certification comes in tiers, commonly referred to as A, AA, and AAA, with higher tiers offering longer benefit periods in exchange for a stronger compliance track record. A company that does not certify must either pay the IVA and recover it later or post a bond or guarantee.

Temporary status also comes with time limits. Raw materials, inputs, packaging, and consumable goods generally must be exported, or their status changed, within 18 months. Certain sensitive goods have shorter windows. Machinery, equipment, tooling, and molds may remain in Mexico for as long as the IMMEX program is active, because they are the productive assets of the plant rather than throughput. Missing a deadline converts a temporary import into an irregular one and exposes the company to duties and penalties.

• IGI (general import tax) is deferred because the finished product is exported
• IVA at 16 percent applies to temporary imports unless the company holds IVA/IEPS Certification from SAT
• Inputs and raw materials generally carry an 18-month temporary window
• Machinery and equipment can stay for the life of the IMMEX program

How Components Flow South and Finished Goods Flow North

A typical Otay Mesa manufacturing cycle runs in two directions across the same border. Components, subassemblies, raw materials, and production equipment cross south from the United States into Mexico. They enter under a temporary import pedimento, the Mexican customs declaration, using the pedimento keys that designate temporary importation under an IMMEX program. That declaration is what records the deferred-duty status and starts the clock on the temporary window.

Inside the plant, those inputs are transformed, assembled, or repaired. The finished goods, along with any scrap and waste that must be accounted for, then cross north back into the United States. On the Mexican side this is recorded as a return or export pedimento that discharges the temporary import. This discharge, called the descargo, is critical: it is the documentary proof that the inputs which came in tax-free actually left the country as finished product. If the numbers do not reconcile, Mexican customs treats the difference as goods that stayed in Mexico and owes tax.

Holding the whole cycle together is inventory control. IMMEX companies must run an automated inventory system that ties every imported input to the exported product it became. The regulatory basis for this is Annex 24 (Anexo 24), the mandatory inventory control system, and for IVA/IEPS certified companies, Annex 31 (Anexo 31), which reports certified inventory to the tax authority. These systems are not paperwork for its own sake. In an audit, they are the evidence that duty deferral was legitimate, so the material flow and the data flow have to match.

• Southbound: components and equipment enter Mexico on a temporary import pedimento
• Inside the plant: inputs are transformed, assembled, or repaired
• Northbound: finished goods return to the US and discharge the temporary import (descargo)
• Annex 24 inventory control ties every imported input to its exported product

US-Side Coordination

Every southbound shipment of components is a US export, and every northbound shipment of finished goods is a US import, so IMMEX operations live inside US customs rules just as much as Mexican ones. On the export side, when goods leave the United States for Mexico, the exporter is generally responsible for filing Electronic Export Information (EEI) in the Automated Export System (AES) when a shipment exceeds 2,500 dollars per Schedule B classification or requires an export license. Accurate export records on the way south make the reconciliation on the way north far cleaner.

On the import side, finished goods coming back into the United States are entered through CBP’s ACE system by the importer of record, who must classify the goods under the Harmonized Tariff Schedule (HTS), pay applicable duties, and cover the Merchandise Processing Fee (MPF) and, for ocean shipments, the Harbor Maintenance Fee (HMF). Most Otay Mesa cargo moves by truck rather than ocean, so ISF 10+2, which applies to ocean cargo and must be filed 24 hours before lading with penalties reaching 5,000 dollars, is usually not the controlling requirement for a border truck crossing. A customs bond, however, is still required for the US entry, either a single entry bond or a continuous bond for a company importing regularly.

Two provisions often shape the duty math. First, USMCA rules of origin determine whether the finished good qualifies for preferential (often duty-free) treatment when it enters the United States, which depends on where the inputs came from and how much value was added in Mexico. Second, the classic tariff provision HTSUS 9802.00.80 has historically allowed US-origin components that are assembled abroad and returned to enter with a duty allowance for the value of those US components, so duty is assessed only on the foreign value added. Which path produces the lowest legitimate duty depends on the bill of materials, so classification and origin analysis should be done before the first shipment crosses, not after.

• Southbound components are US exports: file EEI in AES when over 2,500 dollars per Schedule B or when licensable
• Northbound finished goods are US imports: HTS classification, ACE entry, MPF and, for ocean, HMF
• A US customs bond (single or continuous) is required for the return entry
• USMCA rules of origin and HTSUS 9802.00.80 both affect how much duty is actually owed

IMMEX Program Types and the Shelter Option

IMMEX is not one-size-fits-all. The decree recognizes several modalities. An Industrial IMMEX covers a company that carries out a manufacturing or transformation process. A Services IMMEX (Servicios) covers operations that perform services on export goods, such as repair or refurbishment. A Holding modality (Controladora) lets a certified holding company consolidate the manufacturing operations of controlled companies under one program. And the Shelter modality (Albergue) is the one that matters most to foreign firms testing the border.

Under a shelter (albergue) program, a foreign company can place its machinery, materials, and technology in Mexico and have the actual manufacturing carried out under the IMMEX registration of an established Mexican shelter operator, without forming its own Mexican legal entity or holding its own IMMEX. The shelter operator handles the customs registrations, compliance, and inventory obligations. For a company that wants to prove out cross-border assembly at Otay Mesa before committing to a Mexican subsidiary, the shelter route lowers the barrier to entry considerably.

Choosing a modality is not just a legal formality. It determines who is the importer of record in Mexico, who carries the inventory-control and reporting burden, and how quickly a company can start and stop production. The right structure depends on the company’s volume, its appetite for standing up a Mexican entity, and how long it expects to run the operation.

• Industrial: direct manufacturing or transformation of export goods
• Services (Servicios): repair, refurbishment, and services on export goods
• Holding (Controladora): consolidates controlled companies under one certified program
• Shelter (Albergue): foreign firms produce under a Mexican operator’s IMMEX without forming a local entity

Compliance, Discharge, and Common Pitfalls

The benefit of IMMEX and the risk of IMMEX come from the same place: the promise that temporarily imported goods will be exported. Mexican customs and the SAT enforce that promise through the inventory control system and the discharge records. The most common failure is a mismatch between what came in and what went out, whether from scrap that was not properly documented, inputs that were sold domestically without a change of import regime, or time windows that quietly expired. Any of those can turn deferred duties into an assessment, plus penalties.

A related program worth knowing is PROSEC (Programa de Promoción Sectorial), a sectoral program that reduces the IGI rate on certain inputs regardless of origin. IMMEX and PROSEC are frequently paired, because IMMEX handles the temporary-import deferral while PROSEC can lower the underlying duty rate that would apply if goods were ever nationalized into Mexico. Companies that plan to sell any portion of their output inside Mexico need to understand both.

The practical takeaway is that IMMEX rewards discipline. Keep the Annex 24 system reconciled in real time, watch the temporary-import clock, keep the US export and import records aligned with the Mexican pedimentos, and confirm the USMCA origin position before you rely on duty-free entry. Because a single product crossing at Otay Mesa touches two customs authorities, an error on one side almost always surfaces as a problem on the other.

• The top risk is an inventory mismatch between imported inputs and exported finished goods
• Undocumented scrap, domestic sales, or expired time windows can trigger duty assessments
• PROSEC can lower the underlying IGI rate and is often paired with IMMEX
• Real-time Annex 24 reconciliation is the best protection in an audit