It is the question US customers ask most, and the answer changed several times in 2025 and 2026. This is what applies as of September 2026 to parts machined or printed in Mexico. It is not legal advice: final classification is decided by your customs broker or importer of record.
What USMCA does remove
- The general (MFN) duty of the tariff line, when the part qualifies as originating.
- The Section 301 duty the US applies to certain products from Mexico, for qualifying goods.
- The Merchandise Processing Fee (MPF).
A part machined in Mexico from bar or plate usually qualifies; auto parts also have a regional value content rule. That is why every shipment to the US carries its USMCA certification of origin.
What USMCA does not remove: Section 232
Section 232 taxes the steel and aluminum in certain products, and some auto parts, wherever they come from. As of September 2026:
- Aluminum derivatives on the Section 232 list (for example, HTS 7616.99.51.90): 50% of the part value, or 10% if the aluminum was smelted and cast in the United States.
- Many machinery parts of steel or aluminum (for example, in headings 8483 and 8479): 25%.
- Auto parts on the Section 232 list: 25%. If they qualify for USMCA that 25% is not charged, although the metal 232 may apply.
- Plastic parts and lines such as 8466.93 (machine tool parts): outside Section 232.
The rate is decided first by the tariff line and then by the country where the metal was smelted and cast. That is why our commercial invoice declares, per part, the metal, its weight and that country, which is what US Customs asks for.
Prototypes
A prototype imported only for testing or development may qualify for HTS 9817.85.01, which pays no general duty, 232, 301 or MPF. Your importer claims it at entry; the estimate also shows what it would be if customs does not accept it.
How you see it in your order
In the Customs and duties step we calculate the estimate with these rules for each part, including the carrier's advancement fee and the total to pay on delivery. Rates change often: the estimate is a guide and what customs assesses on the shipment is what applies.