USMCA Article 2.5 & Non-Originating Inputs Under IMMEX: When You Owe Mexican Duties

One of the most expensive misconceptions among US and global manufacturers moving production to Mexico is assuming that IMMEX equals 0% import duties on all global raw materials.

Many CFOs and supply chain directors hear: “Under an IMMEX maquiladora program, we import raw materials into Mexico temporarily without paying duties, assemble them, and export the finished goods back to the United States.”

That statement is only half true. Since 2001 under NAFTA Article 303—and continuing today under USMCA Article 2.5, Article 63-A of the Mexican Customs Law, Article 14 of the IMMEX Decree, and RGCE Rules 1.6.11 to 1.6.17—Mexico is legally prohibited from granting unlimited duty deferral on non-North American inputs that are incorporated into finished goods exported to the United States or Canada.

If your Mexican IMMEX plant imports components from China, Taiwan, South Korea, Vietnam, Japan, or Europe, understanding the exact math of USMCA Article 2.5 is the difference between a 0% tariff supply chain and an unexpected six-figure tax assessment in Mexico.

1. Why USMCA Article 2.5 Exists (The “Anti-Conduit” Rule)

Why would Mexico charge you Mexican import duties on raw materials that never stay in the Mexican domestic market and are 100% exported to the United States?

When the United States, Mexico, and Canada created a duty-free trade bloc, US and Canadian trade negotiators wanted to prevent Mexico’s maquiladora program from becoming a “tariff-free backdoor” where a manufacturer could:

1. Import Chinese or European components into Mexico paying 0% Mexican duty (because of IMMEX temporary import deferral),
2. Perform enough assembly in Mexico to satisfy the USMCA tariff-shift rule, and
3. Ship the finished product into the United States paying 0% US duty (because of USMCA preference).

To prevent third-country inputs from entering North America without paying a tariff at either border, USMCA Article 2.5 (like NAFTA Article 303 before it) treats the US-Mexico-Canada region as a single outer tariff wall for duty-deferral programs when goods are exported to another USMCA Party.

(Note: USMCA Article 2.5 specifically governs goods exported from Mexico to the United States or Canada, subject to the statutory exceptions in Article 2.5.6(a)–(g)—such as goods exported in the same condition, originating inputs, or specific sugar/textile provisions. For exports from Mexico to non-USMCA destinations, duty deferral and no-drawback obligations must be evaluated separately under Mexico’s domestic Article 63-A of the Customs Law, Article 14 of the IMMEX Decree, and any applicable destination Free Trade Agreement—for example, Article 15 of the Mexico–EU Free Trade Agreement / TLCUEM, which restricts drawback when preferential tariff treatment is claimed in the European Union).

2. The “Lesser of the Two Duties” Formula Explained

Under USMCA Article 2.5 and RGCE Rule 1.6.12, when an IMMEX plant exports a finished good to the United States or Canada (Clave RT or virtual transfer followed by export), the Mexican General Import Duty (IGI) owed on the non-originating inputs incorporated into that product is calculated using the “Lesser of the Two Duties” (El Menor de los Dos Aranceles) formula:

Mexican Duty Payable = Max(0, Mexican IGI on Non-Originating Inputs - min(Mexican IGI on Inputs, US/CA Duty Paid on Finished Good))

In plain English: Mexico exempts you from paying Mexican import duties on your non-USMCA raw materials up to the amount of import duties paid on the finished product when it entered the United States or Canada.

Look at the two paradoxical outcomes this formula creates in the real world:

Scenario A: Your Finished Product Qualifies for USMCA (0% US Duty) -> Maximum Mexican Duty Exposure

Suppose your Tijuana IMMEX plant imports $1,000,000 USD of Chinese electronic sub-assemblies and aluminum housings that carry a 10% Mexican MFN tariff (IGI = $100,000 USD). Your plant transforms them in Mexico so the finished product qualifies as USMCA Originating and enters the United States at 0% US tariff ($0.00 paid to CBP):

1. Mexican IGI calculated on the Chinese inputs: $100,000 USD
2. US Import Duty paid to CBP on the finished product: $0 USD (because you claimed USMCA 0% preference!)
3. Lesser of the Two Duties (Exemption Credit): min($100,000, $0) = $0 USD
4. Net Duty Owed to SAT in Mexico (Article 2.5): $100,000 - $0 = $100,000 USD payable to Mexican Customs!

The Paradox: Because your finished product entered the United States duty-free under USMCA, you have $0 USD of US duty receipts to offset your Mexican input duties—so 100% of the Mexican tariff on your Chinese inputs comes due upon export!

Scenario B: Your Finished Product Does NOT Qualify for USMCA (Paid US Duty) -> Offset Credit in Mexico

Suppose the same finished product did not qualify for USMCA, and the US importer paid $65,000 USD in regular US import duties to CBP when the goods crossed into California:

1. Mexican IGI calculated on the Chinese inputs: $100,000 USD
2. US Import Duty paid to CBP (proven with CBP Form 7501 Entry Summary): $65,000 USD
3. Lesser of the Two Duties (Exemption Credit): min($100,000, $65,000) = $65,000 USD
4. Net Duty Owed to SAT in Mexico: $100,000 - $65,000 = $35,000 USD payable to Mexican Customs (provided you present the US Entry Summary CBP Form 7501 within the statutory deadline).

3. How to Legally Reduce Your Article 2.5 Duty to $0: The 4 Tariff Shields

Look closely at the formula above: the entire problem stems from the fact that the Mexican IGI on the non-originating input is greater than 0%. If you legally reduce the Mexican import tariff rate on the raw material itself to 0%, then:

• Mexican IGI on Non-Originating Inputs = $0 USD
• Mexican Duty Payable under Article 2.5 = $0 USD!

Under RGCE Rule 1.6.11, an IMMEX company can determine the Mexican IGI on its non-originating inputs using the preferential or sectoral rate in effect either at the time of temporary import (IN) OR at the time of return (RT), applying any of four legal shields:

(Read our complete implementation guide: PROSEC and Regla Octava Explained).

4. How and When Article 2.5 Duties Are Paid: The Complementary Pedimento (Clave CT)

If your plant exports finished goods to the US or Canada containing non-originating inputs that are not zeroed out by PROSEC, Regla Octava, or another FTA, how do you report and pay the tax to SAT?

Under RGCE Rules 1.6.12 to 1.6.15 and Appendix 2 of Anexo 22:

1. Option 1 — Pay Directly on the Return Pedimento (Clave RT): You can declare and pay the Mexican IGI on the non-originating inputs directly inside the RT export pedimento at the moment the finished goods cross the border.
2. Option 2 — File a Complementary Pedimento (Clave CT) Within 60 Calendar Days:
   • Most IMMEX plants do not pay on the RT because at the moment the truck crosses to Laredo or Otay Mesa, they do not yet have the US Entry Summary (CBP Form 7501) showing the exact US duties paid, or their Anexo 24 system has not yet run the monthly FIFO consumption batch.
   • Under RGCE Rule 1.6.13, the IMMEX company has 60 calendar days following the date of the RT export pedimento to file a Complementary Pedimento (Pedimento Complementario — Clave CT) to declare the non-originating inputs consumed, deduct the US/Canadian duties paid (if applicable), and pay any remaining Mexican IGI.
   • Crucial Warning if You Miss the 60-Day CT Deadline: If you are claiming an exemption credit for US duties paid on CBP Form 7501 and fail to have the US entry proof or file within the statutory window, you lose the right to deduct the US duties (or must pay inflation adjustments and monthly surcharges under RGCE Rule 1.6.15).

5. Don’t Confuse Three Different Rules: USMCA Origin vs. Part 102 Marking vs. US Section 301

When structuring a supply chain that brings Chinese components into a Mexican IMMEX plant for assembly and export to the United States, compliance officers must never conflate three completely separate legal tests: