Vice President Pence has reportedly refused repeated requests for information about his tax returns since taking office, despite releasing returns through 2015 during the 2016 presidential race.

The Wall Street Journal reported Tuesday that Pence has not released any turns since President Trump’s inauguration in 2017 and has offered a similar explanation for his lack of transparency: He is under audit.

{mosads}Tax advisers told the Journal that the president and vice president are regularly audited under IRS protocol and that releasing returns while under audit could complicate the negotiation process between the IRS and Pence.

A spokeswoman for Pence reportedly said this week that the vice president will release updated tax returns before 2020, provided that the audit is completed.

Joe Thorndike, a tax historian, told the Journal, however, that vice presidents have typically released their returns even while under audit, noting that there is no law preventing them from doing so.

“Every one of those tax advisers would also never advise a client to release their tax return to anyone, anywhere, under any circumstances,” Thorndike said, according to the newspaper. “We expect more of presidents and vice presidents.”

The vice president’s income briefly entered the headlines earlier this year amid the partial government shutdown when Pence announced that he would not accept a scheduled pay raise while government employees remained furloughed.

In 2016, Trump became the first major party presidential nominee in decades to refuse to release his tax returns.