U.S. tariff briefing update

The House of Commons Library says U.S. tariff policy is still shifting, with new sector tariffs, carve-outs for Britain, and fresh uncertainty around what comes next. (commonslibrary.parliament.uk) In a briefing published April 14, the library said a 10% U.S. tariff applies to most other UK goods, while steel, aluminium and derivative goods are still at 25%. It said the UK-U.S. Economic Prosperity Deal announced on May 8, 2025 has only been partially implemented. (commonslibrary.parliament.uk) The same briefing says the United States imposed a 25% tariff from January 14, 2026 on semiconductors, semiconductor manufacturing equipment and related products under Section 232, a national-security law. The White House proclamation for that move is dated January 14, 2026. (commonslibrary.parliament.uk) (whitehouse.gov) Tariffs are taxes collected on imports, and the library notes they are paid by importing businesses in the country that imposes them. It says the Trump administration has used them widely since January 20, 2025, including on goods from the UK. (commonslibrary.parliament.uk) One reason the briefing changed this month is that the legal basis changed. The library says a U.S. Supreme Court decision on February 20, 2026 altered the footing for several tariffs, and the Tax Policy Center says the court struck down tariffs imposed under the International Emergency Economic Powers Act while older and sector-specific tariffs remained. (commonslibrary.parliament.uk) (taxpolicycenter.org) Since that ruling, the White House has leaned harder on Section 232 investigations, which tie tariffs to national-security findings by the Commerce Department. On April 2, 2026, Trump issued one proclamation on pharmaceuticals and another on steel, aluminum and copper. (whitehouse.gov 1) (whitehouse.gov 2) The pharmaceutical action is the biggest new risk for exporters. The White House said patented drugs and their ingredients face a 100% tariff, with the rate taking effect in 120 days for certain large companies and 180 days for smaller ones, while generic drugs and biosimilars are excluded for now. (whitehouse.gov) Britain got a better lane than most countries. The House of Commons Library says pharmaceuticals can now enter the United States tariff-free under the UK-U.S. deal, and the White House said UK products would face a lower rate under a separate pharmaceutical agreement. (commonslibrary.parliament.uk) (whitehouse.gov) The library also records Trump floating much steeper duties in other sectors. White House documents show tariffs tied to timber and lumber products rising as high as 50% on some cabinets and vanities from January 1, 2026, and Reuters reported on April 2 that Trump had previously threatened pharmaceutical tariffs as high as 200%. (whitehouse.gov) (usnews.com) For UK exporters, the picture on April 20, 2026 is a patchwork: a 10% baseline on most goods, 25% on steel and aluminium, a January semiconductor tariff, and a pharmaceutical system that now depends on country deals, product type and company commitments. The House of Commons Library briefing reads less like a settled tariff schedule than a map of an argument still in motion. (commonslibrary.parliament.uk)