The process could grind to a halt, however, after Trump's administration said on Friday that it intended to appeal a federal judge's order to allow all companies that paid the invalidated duties to seek refunds, not just the ones that filed lawsuits.
Until the Department of Justice informed the judge of its planned appeal, the refund system overseen by US Customs and Border Protection had been working fairly smoothly.
Refunds reached the bank accounts of the first successful applicants on May 12, about three weeks after importers and their customs brokers could start submitting claims through an online system, according to CBP.
Applications for refunds totalling $US85 billion ($A118 billion) - more than half of the $US166 billion the agency estimated the government owes to companies that paid the tariffs on imported goods - were accepted for processing as of May 22, CBP reported in a legal filing earlier in the week.
It said it had so far directed the Treasury Department to issue $US20.6 billion in refunds.
The administration revealed its appeal preparations while objecting to a demand by Judge Richard K Eaton for CBP Commissioner Rodney Scott to appear in the US Court of International Trade to answer questions about how long it would take to repay all 330,000 importers that might be eligible for refunds.
The judge has scheduled a June 9 hearing on why he should not require the government do whatever it takes to speed up the process.
Justice Department lawyers asked Eaton to allow one or two of Scott's deputies to appear in his place, arguing that as a high-ranking presidential appointee, the CBP chief could not be compelled to testify in court.
They also argued that Eaton exceeded his own authority when he determined in March that the Supreme Court's ruling entitled "all importers of record" to refunds.
"For that reason, defendants intend to appeal the court's universal injunction," the lawyers wrote, adding that CBP would continue to move "as quicky as it can to process refunds in a phased approach" for businesses that filed 485 pending trade court complaints to assert their rights to refunds.
In a terse reply on Friday, Eaton said he needed to hear directly from Scott whether the government would return all of the money it collected between when Trump put what he called "reciprocal" tariffs on most countries in April 2025 and when the Supreme Court struck them down in late February.
"This case involves $US166 billion," the judge wrote.
"It is undisputed that the remedy for this unlawful collection is for the United States government to refund the unlawfully collected duties."
Some US retail chains said they planned to use their tariff refunds to lower customer prices on some items.
Walmart chief financial officer John David Rainey told analysts last week that the company would implement price cuts even though the maximum refund it might be eligible for represented less than half of one per cent of Walmart's $US483 billion in annual US sales.
Some smaller companies told the Associated Press that the partial refunds they have received so far would go toward paying remaining or future tariffs, reducing debt or just keeping the lights on after more than a year of uncertainty and additional import costs.
