President Trump has signed a new presidential proclamation that rewrites how tariffs on steel, aluminum, and copper are calculated, setting off fresh anxiety across Michigan's auto supply chain. The order changes how finished products are treated compared with raw metal inputs, and industry leaders say the revised valuation rules will touch everything from parts to power-grid gear and heavy machinery. Detroit-area suppliers and automakers are still poring over the annexes to figure out which product lines and invoices are about to take a bigger tariff hit.
What the proclamation does
According to the White House, the proclamation, dated April 2 and effective for goods entered on or after April 6, applies Section 232 duties to the full customs value of covered metal articles and their derivatives. It sets a 50% ad valorem rate for articles made entirely or almost entirely of steel, aluminum, or copper, and a 25% rate for many derivative products, while authorizing the Commerce Department and the U.S. Trade Representative to add products on a rolling basis. The administration also created temporarily reduced rates for certain metal-intensive industrial and electrical-grid equipment in an effort to support a domestic buildout push.
Why Detroit automakers care
The policy hits close to home because automakers and suppliers were already reporting hefty tariff tabs last year, a financial blow that The Detroit News said left General Motors, Ford, and Stellantis carrying multi-billion-dollar costs. Those charges have squeezed supplier margins and complicated procurement for parts that rely on imported metals or components. Automakers have been juggling whether to absorb or pass along those costs while reconsidering reshoring plans, supplier contracts, and pricing strategies.
How the new tiers work for suppliers
The proclamation's annexes spell out a tiered tariff structure. Some finished metal goods are taxed at 50% on their full value, many derivative items are set at 25%, and a temporary regime drops certain industrial and grid equipment to 15% (or the higher of 15% and the normal most-favored-nation rate) through December 31, 2027. The White House annex also creates carve-outs for products made with U.S. melted-and-poured or smelted-and-cast metal that can qualify for lower treatment, in some cases a 10% ad valorem rate, if strict origin and composition tests are met. The detailed HTS codes and product lists are included in a separate White House annex.
Implementation and early guidance
U.S. Customs and Border Protection has issued a CSMS notice explaining reporting and valuation rules around country-of-melt-and-pour and other implementation details, while the Commerce Department's Bureau of Industry and Security later made technical corrections to the HTSUS language. According to U.S. Customs and Border Protection, importers must update entries and document metal origins carefully or risk back-assessed duties. Trade advisers and accounting firms have been rolling out client alerts and webinars to walk suppliers through reclassifying parts and estimating duty exposure as shipments move through customs.
What to watch next
Industry reaction so far has been mixed. Metals groups have welcomed the proclamation as a way to shore up domestic capacity, while automakers and construction trade organizations warn that it will push costs onto consumers and large projects. As S&P Global reported, trade groups such as the American Iron and Steel Institute praised the administration for closing valuation loopholes. At the same time, importers and state officials say that seeking refunds or litigating past assessments is likely to be messy, and Axios recently noted that many Michigan businesses remain uncertain about how the refund process will actually work. For Detroit suppliers, the immediate job is less political and more practical: classify shipments correctly, document melt-and-pour origins, and rework contracts to blunt the next round of tariff shocks.
