The US Supreme Court has allowed President Trump’s financial records be examined by prosecutors in New York.
In a related case, the court ruled that this information did not have to be shared with Congress.
“Two hundred years ago, a great jurist of our Court established that no citizen, not even the President, is categorically above the common duty to produce evidence when called upon in a criminal proceeding,” the court said.
“We reaffirm that principle today.”
Mr Trump is the first president since Richard Nixon in the 1970s not to have made his tax returns public.
His lawyers argue that he enjoyed total immunity while in office and that Congress had no valid justification to seek the records.
Two Democrat-controlled House of Representatives committees and New York District Attorney Cyrus Vance demanded several years’ worth of Mr Trump’s taxes in order to determine whether current conflict-of-interest laws on a US president were tough enough.
Trump denies wrongdoing and has called the investigation into his tax affairs a “witch hunt”.
It’s still unknown how the ruling would pan out as Trump’s financial records may remain hidden from public view until charges are filed.