WASHINGTON — An Internal Revenue Service whistle-blower filed a complaint alleging that senior Treasury officials tried to exert influence over the mandatory audit of President Trump’s tax returns, according to a person familiar with the matter.
The whistle-blower came forward to Congress in July with the complaint, which accuses political appointees in the Treasury Department of improperly involving themselves in the audit and putting pressure of some kind on senior officials in the I.R.S. Additional details about the specific allegations in the complaint remained unclear, including when the reported activity took place.
The allegation comes as Mr. Trump is locked in a legal battle with Congress, where House Democrats have sought to obtain six years’ worth of his personal and business tax returns. Mr. Mnuchin has refused a congressional request to release the returns and Mr. Trump has declined to release them despite decades of precedent that presidents make their tax information public.
In August, Representative Richard E. Neal of Massachusetts, the Democratic chairman of the Ways and Means Committee, alerted Treasury Secretary Steven Mnuchin to the existence of the whistle-blower, who he said put forth “credible allegations of ‘evidence of possible misconduct’ — specifically, potential ‘inappropriate efforts to influence’ the mandatory audit program.”
“This is a grave charge that appreciably heightens the committee’s concerns about the absence of appropriate safeguards as part of the mandatory audit program and whether statutory codification of such program or other remedial, legislative measures are warranted,” Mr. Neal wrote.
Mr. Mnuchin, in a letter of response to Mr. Neal on Aug. 13, said he referred the matter to the Treasury Department’s inspector general for tax administration. The Treasury Department declined to comment for this article. The White House did not immediately respond to a request for comment.
The existence of the complaint received little attention after it came to light in August and has recently been overshadowed by a whistle-blower complaint involving a telephone call between Mr. Trump and the president of Ukraine. In that call, Mr. Trump called for Ukraine to investigate former Vice President Joseph R. Biden Jr. and his son’s business in the country.
The person familiar with the complaint, who has not personally reviewed it but is aware of its contents, said it did not directly implicate Mr. Mnuchin.
The Washington Post reported earlier on Thursday that the complaint implicated at least one Treasury Department political appointee and interviewed the whistle-blower.
The Treasury secretary, who is one of Mr. Trump’s closest aides, has said House Democrats are attempting to weaponize the I.R.S. by trying to obtain the president’s returns, and his department has argued that the request for the returns lacks a legitimate legislative purpose. House Democrats have made the request on the basis that they want to review the mandatory audit process that the I.R.S. undertakes to examine presidential returns.
Evidence of political interference in the audit process could buttress the argument that Congress should have access to the president’s returns.
George Hartmann, a spokesman for Senator Charles E. Grassley, the Republican chairman of the Senate Finance Committee, said, “We don’t discuss confidential whistle-blower communications, including whether they exist, unless a whistle-blower requests otherwise.”
Senator Ron Wyden of Oregon, the top Democrat on the Finance Committee, said the complaint was cause for concern and warranted additional investigation.
“It would be negligent for the Finance Committee to fail to investigate a whistle-blower’s allegations of political interference in the presidential and vice-presidential audit process,” Mr. Wyden said in a statement. “A bipartisan committee effort to get to the bottom of this should have been started months ago.”
A spokesman for Mr. Neal declined to comment.
John A. Koskinen, who retired as I.R.S. commissioner in late 2017, said an attempt to intervene in the audit of any taxpayer would be highly inappropriate.
“It would be extraordinary for anybody outside the I.R.S., whether it be at Treasury or anywhere else, to get any outside information about an audit,” Mr. Koskinen said.
Mr. Koskinen said he never witnessed political interference relating to Mr. Trump’s returns while he was commissioner during the Trump administration.
He did note, however, that on one occasion Mr. Mnuchin asked him to make sure that the agency was doing everything possible to keep the president’s tax returns secure.