Mnuchin said the White House has been in touch with Treasury over the issue but did not disclose what the decision might be about releasing the president's long-sought filings. Democrats have issued a letter seeking six years of returns.
Trump refused to release the returns during the 2016 presidential campaign and has retained that stance since winning. The president had said that he would release his returns after they were done being audited, although there is nothing legally in the way of him releasing them.
The House Democrats' letter "is being reviewed by the legal departments and we look forward to responding to the letter," Mnuchin said.
"I have not had any conversations with anybody in the White House about this issue personally," he later added. "I want to be specific. That relates to me and not everybody at Treasury."
The issue of whether the White House and Treasury have been in contact is relevant due to precedent that separates the two entities to prevent undue influence.
Rep. Mike Quigley, D-Ill., questioned whether Mnuchin or Treasury should be making that decision, which he suggested belongs in the hands of IRS Commissioner Charles Rettig. Mnuchin countered that he oversees Rettig, although he did not indicate whom he felt should have final say.
The hearing between Mnuchin and members of an appropriations subcommittee turned contentious several times. Near the end of a hearing that lasted more than an hour, Mnuchin noted that Trump was still elected even though he refused to release his returns during the campaign.
Rep. Tom Graves, R-Ga., called the tax return requests a "political stunt by the new majority."