President Donald Trump delivers remarks in the Roosevelt Room at the White House in Washington, Monday, March 24, 2025. (Pool via AP)A global trade war sparked by Donald Trump’s tariffs could wipe out Rachel Reeves’ spare cash within days, experts have warned.The chancellor announced in the Spring Statement that the Office for Budget Responsibility estimates she will have £9.9 billion of “fiscal headroom” come 2029.However, the OBR also warned that could vanish if Trump goes ahead with his threat to impose a 20% tariff on imports from April 2.In their assessment of the chancellor’s plans, the OBR said in the most “severe” scenario, in which the UK and other nations retaliated against America, the UK’s gross domestic product (GDP) would be 0.6% lower than forecast this year and 1% lower next year.“This would almost entirely eliminate the headroom ... as additional tariff revenue is more than offset by lower receipts from income, corporation and consumption taxes,” the OBR said.Talks between the UK and US on avoiding tariffs remain on