An anonymous tipster who approached the House Ways and Means Committee with a complaint in July accused a political appointee of interfering with the mandatory audit of the president or vice president’s returns, the Washington Post reported.

The whistleblower is reportedly a male, career employee of the Internal Revenue Service.

His complaint focuses on allegations that at least one political appointee at the Treasury Department attempted to interfere with the IRS’s mandatory audit process, in which it audits the tax returns of the president and vice president each year.

The tipster is reportedly speaking to the Washington Post, and declined to tell the newspaper about the details of the complaint.

“I steadfastly refuse to discuss the substance or details of the complaint, but I have some legitimate concerns about reckless statements being made about whistleblowers,” he told the newspaper.

House Ways and Means Chair Rep. Richard Neal (D-MA) received the complaint on July 29, and told a federal judge about it in August as part of a lawsuit that seeks to force the Trump administration to comply with the committee’s demand for the President’s tax returns.