Just days after Treasury Secretary Steven Mnuchin said he would not comply with a House Democratic subpoena for President Trump’s tax returns, a confidential draft IRS memo obtained by The Washington Post called the disclosure “mandatory,” unless the president asserts his executive privilege.

MNUCHIN SAYS HE WON’T COMPLY WITH SUBPOENA FOR TRUMP’S TAX RETURNS

The paper published the 10-page memo that does not mention Trump by name, but appears to add new pressure on the administration.

Mnuchin has been resisting House Democrats’ request for Trump’s tax returns on the grounds that such request “lacks a legitimate legislative purpose” and said his department will not “disclose the requested returns and return information.”

Ways and Means Committee Chairman Richard Neal, a lawmaker from Massachusetts, insisted that the committee is looking into the effectiveness of IRS mandatory audits of tax returns of all sitting presidents, a way to justify his claim that the panel has a potential legislative purpose.

But the IRS document says the law “does not allow the Secretary to exercise discretion in disclosing the information provided the statutory conditions are met” and directly rejects the reason Mnuchin has cited for withholding the information.

“[T]he Secretary’s obligation to disclose return and return information would not be affected by the failure of a tax writing committee … to state a reason for the request,” it reportedly reads, adding that the “only basis the agency’s refusal to comply with a committee’s subpoena would be the invocation of the doctrine of executive privilege.”

“[T]he Secretary’s obligation to disclose return and return information would not be affected by the failure of a tax writing committee … to state a reason for the request.” — IRS memo

HOUSE DEMOCRAT SUBPOENAS MNUCHIN, IRS FOR TRUMP’S TAX RETURNS

The paper said the IRS said the draft memo – titled “Congressional Access to Returns and Return Information” – did not represented the IRS’ “official position." It was not signed.

The standoff between the Congressional Democrats and the administration is likely to lead to a court battle, with Trump reportedly indicating that he’s prepared to fight up until the case reaches the Supreme Court.

The president reportedly likened the request to obtain his tax returns to the Special Counsel Robert Mueller’s investigation into whether the Trump campaign colluded with the Russians, and suggested the effort is designed to damage him politically.

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Trump declined to reveal his tax returns during the 2016 presidential election, claiming he was under audit. Political candidates aren’t required to disclose their tax returns, though traditionally all candidates do.

Fox News' Edmund DeMarche and The Associated Press contributed to this report.