U.S. President Donald Trump on Wednesday signed an executive order preventing the cumulative application of multiple tariffs on the same imported item under specified national security and emergency authorities. The order, retroactively effective from March 4, stipulates that if an article is subject to tariffs under one of five designated legal actions — including those targeting automobiles, steel and aluminum — it will not be simultaneously subject to other listed tariffs, unless specifically permitted.

However, the order explicitly preserves the ability to impose overlapping tariffs on steel and aluminum products, provided those products independently meet the criteria laid out in related proclamations. The U.S. Customs and Border Protection agency has until May 16 to implement changes to the Harmonized Tariff Schedule reflecting the new policy, while agencies including the Commerce Department and USTR will issue interpretive guidance. Other tariffs, including those under Section 301 and antidumping laws, remain unaffected.