Trump has declined to make his tax returns public, saying he is being audited and would make the returns public when that is over. IRS officials have said a taxpayer is free to make returns public even if they are under audit.

Last summer Buffett spoke at a campaign rally in Omaha for Clinton, introducing her to the audience and challenging Trump to a joint appearance during which he and Trump both would make their tax returns public and answer questions. That hasn’t happened.

In Monday’s press release, Buffett said his tax returns have been audited “multiple times” and are being audited now by the Internal Revenue Service.

“I have no problem in releasing my tax information while under audit,” Buffett said. “Neither would Mr. Trump — at least he would have no legal problem.”

The bulk of Buffett’s wealth is tied up in Berkshire stock. He received a $100,000 salary last year from Berkshire, an amount that hasn’t changed for years, and $370,244 for personal and home security costs.

The source of the rest of his income isn’t public but likely comes from other investments.