The beneficiaries may include retail giants, such as Costco, Gap, Home Depot, Kohl’s, Lowe’s, Target and Walmart. For some, analysts estimate that the refunds may total into the billions of dollars apiece, leaving them with a choice of whether to keep the money or share it with consumers, even if indirectly in the form of future discounts.

But almost none of those U.S. retailers commented by Thursday on their exact plans. Only Costco promised previously to pass savings on to customers, without explaining how, as the buy-in-bulk company faces one of a series of class-action lawsuits from furious Americans who believe they are owed refunds.

Heather Boushey, who served on the White House Council of Economic Advisers under President Joseph R. Biden Jr., described the refund process as a “windfall for businesses,” some of which foisted the tariffs on consumers.

“American families,” she added, “are certainly the losers.”

That could turn the tariff refunds into a divisive political issue, at a moment when a majority of voters have already expressed dissatisfaction with the president’s handling of the economy. Democrats have demanded that the administration return the money to families, but Mr. Trump has opposed returning the money at all — and he suggested this week that it would be “brilliant” if companies chose to forgo repayment.

The White House did not respond to a request for comment.

For more than a year, Mr. Trump has insisted that foreigners, not Americans, have shouldered the financial burden of his punishing global trade war. But the data has always told a more complicated story, one in which Americans have actually been left to pay a substantial toll.