Proclamation 11021, signed April 2, 2026, restructured the entire US Section 232 tariff regime for aluminum, steel, and copper. For aluminum specifically, the duty rate was set at 50% ad valorem on the full customs value of all primary and downstream aluminum articles, with no country exemptions — Canada and Mexico, which had previously enjoyed partial relief under USMCA, now face the same rate as everyone else. (FACT: Proclamation 11021, April 2, 2026; CRS report IN12519, May 18, 2026)
The tariff rate had already risen from the original 10% (2018) to 25% (February 2025) under Proclamation 10947. The April 2026 proclamation added a third tier: 25% on derivative articles (fabricated aluminum products, parts, and components) and 15% on certain metal-intensive industrial and grid equipment through 2027. Products containing 15% or less steel, aluminum, or copper by value are exempt. (FACT: LegalClarity, May 17, 2026; US Tariff Tracker, May 19, 2026)
The end of country exemptions is the most consequential change. Canada shipped roughly 2.9 million tonnes of primary aluminum to the US in 2025, representing approximately 60% of total US primary aluminum imports. Under the previous regime, Canadian aluminum faced a 25% tariff with a partial relief mechanism tied to USMCA commitments. Proclamation 11021 terminated that mechanism. Canadian and Mexican producers may still apply for conditional relief, but only by making binding investment commitments in US production capacity — and a high residual tariff floor remains. (FACT: Cyprus-CEO, May 20, 2026; DOC notice, April 23, 2026)
The Tax Foundation estimated that the 2026 Trump tariffs — including Section 232, Section 301 China tariffs, and Section 122 reciprocal tariffs — amount to an average tax increase of roughly $1,500 per US household, the largest as a share of GDP since 1993. (FACT: Tax Foundation, May 21, 2026) For industrial buyers of aluminum, the cumulative effect is a structural increase in the cost of imported metal that no exemption process is likely to offset in the short term.
The 50% tariff applies to the FULL customs value of the imported aluminum, not just the metal content. A buyer importing Canadian primary aluminum at $3,600/t LME-equivalent now pays an additional $1,800/t in duty — on top of the LME price, regional premium, and freight. For a buyer purchasing 1,000 tonnes/month, that is $1.8 million/month in新增 tariff cost. Options: (1) Shift to domestic supply where available — US smelter capacity is limited but idled capacity exists at Century Aluminum and others. (2) Evaluate secondary/recycled aluminum, which is not subject to Section 232 if produced domestically. (3) Model the full landed cost including tariff before committing to import volumes — the 50% duty changes the economics of Canadian and overseas supply alike. (4) Monitor the USMCA review in July 2026 — it could reopen the exemption question.