IMMEX & PROSEC: Technical Guide for Chinese Manufacturers

For a Chinese company modeling a Mexican operation, the difference between profit and loss often sits in two federal programs. IMMEX (Industria Manufacturera, Maquiladora y de Servicios de Exportación) and PROSEC (Programas de Promoción Sectorial) determine whether your imported inputs enter at the standard most-favored-nation duty rate, a higher surcharge-level rate, or a sharply reduced preferential rate — with the spread between scenarios representing a material share of landed cost.

Both programs carry precise legal mechanics, filing requirements, and ongoing obligations. Reading them correctly at the modeling stage prevents costly assumptions later.

The IMMEX program (Decreto IMMEX) lets a qualifying company temporarily import inputs, components, machinery, and equipment without paying import duties — and without paying VAT if the company holds VAT/IEPS certification. The condition is that those goods feed a manufacturing, repair, or service operation oriented toward export. The program is administered by the Ministry of Economy (Secretaría de Economía) with customs oversight by SAT.

The mechanism is temporary importation, not exemption. Raw materials, parts, and packaging enter Mexico duty-free and must be returned, exported, transferred, or regularized within the term set by the Customs Law. Machinery and equipment may remain under the temporary regime for as long as the IMMEX authorization stays valid.

The export discipline is not optional. The IMMEX decree conditions the authorization on sustained export activity, with the specific sales threshold set out in the decree itself. A company that falls below the required export level puts its authorization at risk, so the export commitment must be verified against the current decree text at the modeling stage.

PROSEC addresses a different problem than IMMEX. It grants preferential import tariffs on specified inputs by industrial sector — and it applies whether the finished product is exported or sold inside Mexico. IMMEX is export-oriented; PROSEC is not.

The structure matters for accurate modeling. PROSEC covers a defined set of industrial sectors published in the Diario Oficial de la Federación, and the decree is amended periodically. There is no single rate per sector. The preferential tariff is set per HS fraction (fracción arancelaria): many covered fractions qualify for duty-free treatment, while others carry low single-digit ad valorem rates according to the current PROSEC annexes. The range spans from full elimination to modest reductions, depending on the specific fraction.

The practical consequence is precise. You cannot look up “the automotive PROSEC rate.” You must map each imported item to its eight-digit Mexican HS fraction, confirm that fraction appears in the current PROSEC annex for your registered sector, and read its assigned rate.

The PROSEC sectors most relevant to Chinese manufacturers concentrate in four verticals: electronics and computing, automotive and auto parts, aerospace-adjacent categories, and machinery and equipment.

The two programs stack. IMMEX defers or exempts duty on temporary imports destined for export; PROSEC reduces the underlying IGI (Impuesto General de Importación) rate on the same inputs, protecting the operation when goods are sold domestically or when duty must be crystallized.

Consider an automotive manufacturer importing rolled steel that faces a general IGI duty without PROSEC. Under the automotive PROSEC sector, the applicable fraction may qualify for a sharply reduced or eliminated rate. On a recurring shipment, the difference between the general rate and the PROSEC rate compounds across a full year of imports.

Applications for IMMEX are filed electronically with the Ministry of Economy through VUCEM (Ventanilla Única de Comercio Exterior Mexicano). The company must be a Mexican legal entity with an active RFC, an advanced electronic signature (e.firma), and the favorable SAT tax-compliance opinion required by the program rules.

The filing itself is document-heavy. It must include the description of manufacturing processes, evidence of installed production capacity, the tariff classifications for goods to be imported and exported, proof of legal possession of the facility with photographs, export contracts or purchase orders, and an investment program detailing layouts, planned headcount, and estimated volumes.

Duty savings are only part of the internal case. The second line CFOs underestimate is statutory employer cost, and the error is usually double-counting.

Budget mandatory employer burden at roughly a third above base salary. Combining IMSS, INFONAVIT, SAR, and state payroll tax, government contributions add on the order of a third above base salary for a typical manufacturing risk class. That figure carries assumptions — IMSS risk class, salary level, and workforce age all move it — so treat it as a planning band and validate the rates with IMSS and your state authority.

One caution: PTU (profit sharing) is calculated as a statutory share of taxable profit, not a percentage of salary. Do not add it to a salary-based labor-cost total, or your model will overstate cost. The applicable rate is set by federal labor law and should be confirmed against the current Ley Federal del Trabajo text.

For wage floors and currency conversion, model against the current CONASAMI minimum wage for the general and northern border zones, and convert using the current Banxico FIX rate. Both figures are updated regularly, so pull the live values when finalizing the model.

The gap between reading these rules and operating under them is where most first-time entrants lose time. Under the shelter model, the Chinese company runs production while the shelter operator holds the IMMEX and PROSEC registrations, maintains Annex 24, files the INEGI reports, and manages IMSS compliance and customs traceability.

This is where operational depth is measurable. American Industries Group brings more than five decades of operational experience supporting over 300 foreign manufacturers across 17 industrial parks and 10 operating regions. That footprint means the HS mapping, VUCEM filing, and ongoing compliance are handled by teams that manage these programs daily.

For a Chinese CFO, the structural value is entering the market under an existing compliance architecture rather than building one from zero. The return-rate thresholds, bond requirements, and Annex 24 audits become the operator’s operational responsibility, defined in the service agreement.

IMMEX and PROSEC are not interchangeable. IMMEX defers duty on temporary imports for export; PROSEC lowers the underlying tariff on your inputs by HS fraction across the covered sectors, whether you export or sell domestically. Stacked correctly, they can move a Chinese-origin input from a high MFN duty rate toward a sharply reduced or eliminated preferential rate.

The decision hinges on precision — every input mapped to its eight-digit HS fraction, every fraction checked against the current DOF annex, every compliance obligation running from day one. For a Chinese manufacturer building the internal business case, the next step is a fraction-by-fraction review of your actual input list against both program annexes to quantify the real savings for your operation.