U.S. tariff revenue at risk in Supreme Court ruling tops US$175 billion, Penn-Wharton estimates

More than US$175 billion in U.S. tariff collections are at risk of having to be refunded if the U.S. Supreme Court rules against U.S. President Donald Trump‘s broad emergency tariffs, Penn-Wharton Budget Model economists said on Friday.

Their estimate, produced at a request from Reuters, was derived from a ground-up forecasting model that uses tariff rates by product and country for specific duties imposed by Trump, including those under the International Emergency Economic Powers Act (IEEPA), said Lysle Boller, senior economist for Penn-Wharton Budget Model (PWBM), a non-partisan fiscal research group at the University of Pennsylvania.

The U.S. Supreme Court could rule on the legality of the IEEPA-based tariffs as early as Friday. If they are struck down, importers are expected to scramble for refunds from the U.S. Customs and Border Protection agency on import duties paid over the past year.

Trump has touted the revenue generated by all of his tariffs, estimated by the Congressional Budget Office at about $300 billion annually over the next decade, but the estimates show that a substantial amount may need to be refunded if the court rules against Trump.

Refunds of $175 billion would exceed the combined fiscal 2025 outlays from the Department of Transportation at $127.6 billion and the Department of Justice at $44.9 billion.

Boller said the PWBM model, built for long-term revenue forecasts, cross-references U.S. Census Bureau import data on around 11,000 product import categories based on eight-digit tariff codes across 233 countries, and applies statistical forecasting methods to come up with about $500 million in IEEPA-based revenue collected daily. As of Thursday, that model estimated $179 billion in total receipts under IEEPA since Trump began imposing tariffs under that law in February 2025.