Since the new year our Mexico desk has spent more time on customs paperwork questions than on freight rates, and there is a reason for that. On 1 January 2026 the largest overhaul of Mexican customs law in roughly three decades took effect, and most import teams we talk to are still treating it as a single tariff story when it is really two separate changes landing at once. GetTransport.com moves freight on US to Mexico and ocean lanes into Mexican ports, so this is the operational read for a shipper, forwarder, or IMMEX operator on what actually changed and what to fix before your next entry, not a legal opinion on the reform.
Keep the two instruments separate, because casual coverage blends them. The first is the reform of the Ley Aduanera, the Customs Law, published in the Diario Oficial de la Federación on 19 November 2025. That one rewrote liability, documentation, and IMMEX controls. The second is a tariff decree published on 29 December 2025 that raised import duties on 1,463 tariff lines. Both took effect on 1 January 2026, and a further amendment to the Customs Law Regulations followed on 23 February 2026 with the implementing detail. The compliance reform is the part that changes how you file every entry; the tariff decree is the part that changes what you pay on non-FTA goods.
Joint liability: your broker can no longer absorb your mistakes
The change with the widest blast radius is liability. The reform repealed the provisions of Article 54 that let customs agents disclaim responsibility for false or inaccurate data supplied by the importer. Under the new text, as DLA Piper reads it, the customs broker is jointly and severally liable, a responsable solidario, for the veracity of the information, the correct tariff classification, the valuation, and the payment of duties, taxes, and anti-dumping duties. Liability is no longer subsidiary, and a broker agency's partner-agents share it too.
That reshapes the importer-broker relationship in a way shippers feel immediately. Because the broker now carries real exposure, brokers are running proper know-your-client checks before they transmit anything. They have to confirm the importer is properly identified and holds its compliance documents, verify that clients are not on the SAT Article 69-B blacklist of simulated-operations taxpayers, and check that the client has the physical and systems infrastructure to actually operate. If your broker has started asking for documents they never requested before, this is why. The practical effect is that a misclassification or a thin valuation file is no longer a quiet administrative fix between you and your agent; it is a shared legal liability with penalties attached.
The Expediente Electrónico: every entry is now a documentation project
The reform requires a comprehensive electronic file, the Expediente Electrónico, behind every import and export transaction. According to KPMG's read of the new minimum contents, that file has to hold the CFDI digital tax receipts, bank transfers and proof of payment, commercial contracts, a customs valuation analysis, insurance documentation, and proof of payment of transport and other customs surcharges. This is a real expansion, and the file has to be retained for five years from the date the declaration was or should have been filed, with retention running for the entire time imported fixed assets or machinery remain in your possession.
Supplier verification is the piece that trips up importers used to the old regime. As QIMA describes it, you now have to document that your foreign supplier has both the legal and the physical capacity to supply the goods, meaning incorporation documents, evidence of legal representation, and proof of active operations, gathered before the transaction rather than reconstructed later. Sitting alongside the file is the electronic Manifestación de Valor. C.H. Robinson dates the mandatory electronic submission through the VUCEM single window to 31 March 2026, with full enforcement following on 31 May 2026, and the importer, not the broker, is the party that transmits it. Confirm your own go-live internally, because a few sources push the fully-mandatory date later into 2026 and you do not want to plan against the wrong one.
IMMEX operators: watch the temporary-import clock and every transfer
If you run an IMMEX or RFE program, three details need attention this quarter. The maximum period for temporary imports has been cut, with the headline figure reported as a move from ten years down to five, though sources differ on exactly which categories the cut reaches, so re-baseline your own inventory against the shorter cap rather than assuming it misses you. On program cancellation, the 60-calendar-day rule has been elevated into the law itself: temporarily-imported goods must be returned or have their regime changed within 60 days, and failure generates immediate tax credits.
The other IMMEX trap is transfers. Joint tax liability now follows the traspaso of temporarily-imported goods between IMMEX companies, regardless of how many times the goods change hands, so inter-company transfer records have to reconcile cleanly. DLA Piper also flags an expanded Article 59-V dossier: you now have to keep technical and accounting documentation proving the goods were effectively transformed, elaborated, or repaired, plus the financial flows and valuation adjustments behind them. And at bonded facilities the Regulations set hard clocks, a maximum of 20 calendar days from clearance to deposit goods in a general bonded warehouse, discrepancies reported within 24 hours of arrival, and real-time inventory with video surveillance whose records SAT can use as evidence.
The tariff hikes hit non-FTA origin, not USMCA goods
Now the money part, and here the good news for a North American shipper is that the duties are aimed elsewhere. The 29 December 2025 decree raised MFN duties on 1,463 eight-digit tariff lines across 17 industrial sectors, with rates running from 5% to 50% and, according to the International Trade Administration, an average increase of roughly 35%. The 50% ceiling lands on automobiles and auto parts, matching Mexico's WTO bound rate, and Crane Worldwide notes that around 316 subheadings moved from a zero duty to a positive one. Sectors hit include automotive, textiles and apparel, footwear, leather, steel, aluminum, plastics, paper, toys, furniture, and appliances.
The critical qualifier is origin. These duties apply only to imports from countries with no active free-trade agreement with Mexico, which in practice means China, India, South Korea, Vietnam, Thailand, Indonesia, Brazil, Taiwan, Russia, Turkey, and a handful of others. Goods that originate under USMCA or another Mexican FTA are exempt. A second decree, published in the DOF on 23 April 2026 and in force the following day, added 185 more tariff lines at 5% to 35%, including wind-turbine sets at 5% and trailers and semi-trailers at 35%, landing days after US Trade Representative Greer visited Mexico City. The first decree is written to run through 31 December 2026, and analysts widely expect it to be renewed, so treat the higher landed cost on Asian-origin inputs as structural rather than temporary. If you are sourcing components from Asia for Mexican assembly, this is the moment to recompute landed cost and to test whether the finished good genuinely qualifies for FTA origin, which connects directly to the rules-of-origin pressure we cover in our USMCA joint review scenario guide.
Penalties moved from a slap to a real threat
The enforcement teeth are what make the documentation work non-optional. Non-compliance with non-tariff measures and prohibited or restricted goods was reclassified as a serious infraction, and DLA Piper puts the fine band at 250% to 300% of the commercial value, up from a former range that sat around 2% to 10%. Smuggling and false declarations draw fines reported in the 70% to 250% range, and bonded-warehousing violations run 70% to 100% of customs value. Errors on the Value Manifestation carry fixed peso fines per operation, with sources citing figures that range into the tens of thousands of pesos and recurrence allowing the maximum. On top of the fines, consequences now stack: precautionary seizure, suspension or cancellation of your importer registry or the broker's license, and criminal referral where authorities see a pattern of evasion. The reform also makes suspension of the Padrón de Importadores, the importers' registry, an explicit escalation, so an address mismatch or a run of late filings that once meant a warning can now cut off your ability to import at all.
What to do now
The work splits into a documentation rebuild and a sourcing review. From what we are running with importers, the near-term sequence looks like this:
- Rebuild the per-shipment electronic file so every entry carries the CFDI, proof of payment, contracts, insurance, freight and surcharge payment evidence, and a written valuation analysis, and store it for five years.
- Vet every foreign supplier before ordering, keeping incorporation documents, legal-representation proof, and evidence of active operations in the file.
- Validate tariff classification defensively with written rationale, because misclassification is now a joint liability that can trigger penalties running well into three figures as a percentage of value.
- If you run IMMEX, audit temporary-import aging against the shorter cap, keep Article 59-V transformation evidence, and reconcile every inter-company transfer.
- Recompute landed cost on all non-FTA-origin inputs against the 5% to 50% duties and the April additions, and test whether re-sourcing or genuine FTA qualification changes the math.
- Verify your Padrón status, fix any address or filing issues, and confirm your broker is current on re-certification and running the new client checks.
Duty deferral is worth a hard look for anyone caught by the tariff side, because a bonded structure can delay or avoid the duty on goods that are re-exported rather than sold into Mexico, which we walk through in our bonded warehouse duty-deferral guide.
How this fits the USMCA review and the transshipment crackdown
None of this is happening in isolation. The tariffs are deliberately aimed at non-FTA, largely Chinese-linked, origin, which lines Mexico up with US pressure ahead of the trade review. The statutory USMCA joint review on 1 July 2026 saw the US decline to trigger a full renewal, moving the parties onto an annual review track, and absent renewal the agreement would automatically expire in July 2036. The second tariff decree arriving three days after the US Trade Representative's visit was not a coincidence; it was framed around complementary trade actions and stronger rules of origin.
For a shipper, the customs reform is the domestic enforcement toolkit that makes all of that operational. Supplier verification, digital traceability, and joint liability are exactly what a customs authority needs to police a Chinese supplier relocating to Mexico to claim USMCA preference, which is the primary target of the parallel US transshipment enforcement we detail in our transshipment crackdown guide. Mexico still drew around 41 billion dollars of foreign investment in the first three quarters of 2025 on the back of nearshoring, so the door is open, but the cost of a China-in, re-export-out model without clean origin and documentation just went up sharply.
Frequently asked questions
Do the new Mexican tariffs apply to goods I ship from the United States?
Generally no. The 2026 tariff decrees raise duties on imports from countries with no free-trade agreement with Mexico, targeting origins such as China, Vietnam, and South Korea. Goods that qualify as originating under USMCA are exempt. The catch is that qualification has to be genuine and documented, because the customs reform gives Mexican authorities the supplier-verification and traceability tools to challenge a weak rules-of-origin claim.
What is the Expediente Electrónico and how long must I keep it?
It is the comprehensive electronic file the reform now requires behind every import or export, holding the CFDI, proof of payment and bank transfers, contracts, a valuation analysis, insurance, and transport and surcharge payment evidence. It must be retained for five years from when the declaration was or should have been filed, and for the whole time any imported fixed assets remain in your possession.
My customs broker suddenly wants more documents. Why?
Because the reform made brokers jointly and severally liable for the accuracy of what they file, including classification, valuation, and duty payment, and repealed the old exemption that let them disclaim responsibility for importer-supplied data. Brokers now have to run know-your-client checks, including screening against the SAT Article 69-B blacklist, before transmitting an entry. The extra requests are the broker managing real legal exposure, not bureaucracy.
I run an IMMEX program. What is the single most urgent thing to check?
Temporary-import aging. The maximum temporary-import period was shortened, widely reported as ten years down to five, so re-baseline your inventory against the shorter cap and identify goods approaching the limit. Also prepare for the 60-day window to return or regularize goods if a program is cancelled, and make sure your Article 59-V records prove the goods were actually transformed, since transfers between IMMEX companies now carry joint tax liability.