President Donald Trump has said the US will apply a 15% global tariff under the 1974 Trade Act after the Supreme Court struck down his earlier duties. The move, posted on Saturday on Truth Social, replaces the 10% levy he outlined on Friday. The White House has yet to say if the higher rate will start on Tuesday 24 February 2026, when the 10% charge was due to take effect.

For UK exporters, the headline is simple: most goods entering America could face an extra 15% at the US border for roughly five months before Congress must be asked to extend it. On a £250,000 order of homeware shipped DDP to a US retailer, that is around £37,500 in extra duty before customs brokerage and financing costs. For firms running 10–12% operating margins, that turns healthy orders into breakeven without swift repricing.

The administration is using Section 122 of the Trade Act of 1974, a little‑used power that caps temporary import surcharges at 15%. Officials have also signalled carve‑outs for areas such as critical minerals, some metals and pharmaceuticals. However, businesses should expect a patchwork in practice: existing measures on steel, aluminium, lumber and auto‑related products introduced under different statutes continue unaffected by the court ruling, while any new exemptions will be set in the Federal Register notice.

Friday’s Supreme Court decision was a 6–3 rebuke of last year’s sweeping tariffs imposed under the 1977 International Emergency Economic Powers Act. Chief Justice John Roberts joined the court’s three liberals and two of Trump’s own nominees, Amy Coney Barrett and Neil Gorsuch, to form the majority; Clarence Thomas, Brett Kavanaugh and Samuel Alito dissented. The judgment narrows a key tool the White House had been using and forces a pivot to the time‑limited 1974 mechanism.

The politics are running hot. Trump called the decision “ridiculous” and said the higher tariff is needed to shore up domestic manufacturing and reduce the US trade deficit. Yet Commerce Department data show the deficit has widened compared with 2024, nearing $1.2tn (£890bn) on a rolling basis this week, underlining how blunt broad tariffs can be as instruments of trade rebalancing.

Reactions from businesses are split along familiar lines. Drew Greenblatt, who runs Baltimore‑based fabricator Marlin Steel, called the court ruling a setback for blue‑collar wages and reshoring. John Boyd, a Virginia soybean farmer and head of the National Black Farmers Association, called it a clear loss for the president and a win for producers reliant on export markets. For UK readers, that divergence mirrors the likely split between capital‑goods exporters who sell into US industry and consumer‑goods brands that battle on shelf price.

The UK government said it expects Britain’s “privileged trading position with the US” to continue, and a White House official indicated that countries with prior deals, including the UK, would now face the global tariff under Section 122 rather than any lower rate negotiated before. London also noted that existing understandings on steel, aluminium, autos, aerospace and pharmaceuticals were not directly affected by the court ruling. In short, most big UK‑US trade flows are protected by separate regimes, but many everyday shipments will not be.

European leaders warned about the economic cost of volatility. France’s President Emmanuel Macron said Paris will adapt but favours reciprocity over unilateral moves. Germany’s Chancellor Friedrich Merz cautioned that uncertainty around tariffs is “poison” for growth and promised to coordinate an EU line ahead of his US visit. For UK firms supplying both the EU and US, that signals potential for fast‑moving policy responses on either side of the Atlantic.

Refunds are now a live issue. The Supreme Court opened the door for importers to seek reimbursement of the unlawful duties collected under the struck‑down approach. The US Chamber of Commerce’s Neil Bradley urged swift refunds to more than 200,000 small importers, while the National Retail Federation pressed for a seamless process through the courts. The White House has hinted any repayments will be contested, which could tie up cash for years unless Congress or the Treasury sets out a clear route.

UK companies that paid US duties via their American customs brokers should talk to those brokers now about filing protests and preserving rights. Keep entry summaries, bills of lading and duty payments organised, and assess whether to join group actions through trade associations. None of this replaces legal advice, but the administrative basics are the same: prove the duty was paid, show it falls within the scope of the ruling and meet the filing deadlines.

Operationally, exporters should revisit Incoterms and pricing with US buyers this week. If you sell DDP, your firm will likely shoulder the tariff unless contracts are amended; if you sell FOB or FCA, your buyers may seek price reductions to offset their new costs. Confirm HS codes, look for any announced carve‑outs, and consider temporary surcharges or shorter quote validity. Finance teams should re‑forecast FX, freight and duty together; the combined effect matters more than any single line item.

The immediate dates to watch are Tuesday 24 February 2026 for implementation and the roughly 150‑day mark when Congress must authorise any continuation. Expect litigation and lobbying in parallel. For UK SMEs, the working assumption should be a 15% duty on most consignments into the US from next week until at least early summer, with scope for exemptions to evolve quickly. Price clearly, communicate early and keep the paperwork tight; in this environment, discipline is a competitive edge.