If the U.S. Supreme Court decides that President Donald Trump’s IIEPA tariffs are illegal, companies large and small may be eligible for refund payments that in total could reach hundreds of billions of dollars. But trade attorneys warn that tariff refunds could be delayed, depending on how U.S. courts and U.S. Customs go about issuing the payments.

President Trump wrote in a social media post on Jan. 12 that “it would take many years to figure out what number we are talking about and even, who, when, and where, to pay.” He added: “It would be a complete mess, and almost impossible for our Country to pay.”

But importers and customs experts have been pushing back on Trump’s claims, saying rather than being a “messy” process, because the tariffs being paid are itemized the process for refunding the money should be straightforward.

There are several scenarios that could impact the timing of refunds, according to Michael Lowell, partner and chair of the global regulatory enforcement group at Reed Smith.

“There is no set timeline on when refunds will be given back,” said Lowell.