Mexico's 2026 Customs Law Reform: What Changed and How It Affects U.S. Companies

What changed on January 1, 2026

Mexico published a comprehensive reform to its customs framework effective January 1, 2026. This is the most significant change to Mexican trade regulation in decades, affecting tariff rates, compliance obligations, digital requirements, and enforcement. If you export to Mexico, these changes directly impact your operations and costs.

Tariff increases: 1,463 codes affected

Mexico increased MFN (Most Favored Nation) tariff rates on 1,463 tariff codes across 20+ chapters. Affected industries include: automotive, textiles, plastics, steel, appliances, aluminum, footwear, paper, leather goods, furniture, glass, toys, motorcycles, and trailers. Rate increases range from 5% to 50%.

If your products are shipped from a USMCA country AND qualify under rules of origin, these increases don't affect you — USMCA preferential rates remain 0% for most products. But if you source components from China or other non-USMCA countries, the increased MFN rates may apply.

MVE (Electronic Value Declaration) — mandatory by regime from November 2026

The MVE transition period ends October 31, 2026. Filing then becomes mandatory by customs regime: November 1, 2026 (processing, transformation or repair in a bonded facility), November 15 (strategic bonded facility), December 1 (in-transit goods), December 15 (bonded warehouse), January 1, 2027 (temporary imports) and January 15, 2027 (definitive imports).

Once it applies to your regime, every import requires an Electronic Value Declaration (MVE) submitted through VUCEM. The importer must sign it with an electronic signature (e.firma). This is a new document that didn't exist before — and it must be filed BEFORE customs clearance. For U.S. companies importing DDP, this means you need an e.firma and a process for generating and signing the MVE.

Joint liability: brokers now share risk

The reform establishes that importers, exporters, AND customs brokers are jointly responsible for the accuracy of customs declarations including tariff classification, valuation, and tax payment. This means your customs broker has more skin in the game — they may be more conservative in classification and valuation to protect themselves, which could mean higher duties or more documentation requests.

Enhanced digital enforcement

Mexico's SAT has significantly upgraded its digital enforcement capabilities: automated risk profiling using AI, cross-referencing of customs declarations with tax filings, real-time monitoring of import patterns, and reference price databases for common products. Undervaluation and misclassification are much more likely to be caught than before.

IMMEX program changes

Companies operating under IMMEX (maquiladora) programs now face stricter requirements: listing under specific annexes and legal decrees to maintain eligibility, enhanced inventory tracking and reporting, and greater scrutiny of temporary import durations. If your Mexican operations rely on IMMEX, review your compliance status.

What to do now

1. Review your tariff codes — check if any of the 1,463 affected codes apply to your products
2. Verify USMCA eligibility — if you qualify, the tariff increases don't affect you
3. Prepare for MVE — get an e.firma if you're the importer of record, or ensure your buyer/broker has a process
4. Update your landed cost calculations — tariff rates may have changed
5. Audit your customs broker — make sure they're up to date on the reform requirements