The deal does not include tariffs on steel, an especially important piece of bilateral trade. Instead, talks are still going on about whether steel tariffs will be cut to zero as planned in the provisional agreement.
Trump and Starmer announced in May they'd struck an agreement that would slash U.S. import taxes on British cars, steel and aluminum in return for greater access to the British market for U.S. products including beef and ethanol.
But it did not immediately take effect, leaving British businesses uncertain about whether the U.K. could be exposed to any surprise hikes from Trump.
British businesses, and the U.K. government, were blindsided earlier this month when Trump doubled metals tariffs on countries around the world to 50%. He later clarified the level would remain at 25% for the U.K.
Starmer said Monday that the trade agreement is "in the final stages now of implementation, and I expect that to be completed very soon."
Trump said the deal is "gonna produce a lot of jobs, a lot of income."