United States and Mexico Launch Joint Customs Enforcement to Prevent Steel and Aluminum Tariff Evasion

In a joint effort to combat tariff evasion, the United States and Mexico implemented a new customs enforcement mechanism on August 6, 2026. According to the Office of the United States Trade Representative (USTR), the primary source of the announcement, the joint initiative requires importers of steel and aluminum products to declare the country of origin where the raw metal was melted and poured. This requirement is tied to specific HS codes under Chapter 72 (iron and steel), Chapter 73 (articles of iron or steel), and Chapter 76 (aluminum and articles thereof).

As reported by Reuters and Bloomberg, the measure is designed to prevent the transshipment of Chinese-origin metals through Mexico, which has been used as a route to evade US Section 232 tariffs. By requiring strict documentation at the border, the joint mechanism aims to ensure that only metals genuinely produced within the USMCA region benefit from preferential trade terms. The “melted and poured” standard represents a stricter level of origin verification, moving beyond simple processing or finishing locations.

The trade implications for the metals sector are substantial. Importers must now adapt to more rigorous documentation standards, which could lead to administrative delays at the border. However, the joint mechanism is expected to level the playing field for domestic producers in both the US and Mexico by ensuring that tariff obligations are enforced fairly. Companies importing goods classified under Chapters 72, 73, and 76 must work closely with their suppliers to obtain the necessary mill test certificates and country-of-origin documentation to avoid border delays.

This joint enforcement action highlights the increasing use of HS codes as a tool for trade remedy enforcement. By targeting specific classifications, customs authorities can apply highly focused monitoring to high-risk product categories. Exporters and customs brokers operating in the North American market will need to update their compliance protocols to accommodate these new declaration requirements, reflecting a broader trend toward greater transparency in global metals supply chains.