The IRS statute, known as 6103, says three people on Capitol Hill - the Senate Finance Committee chairman, the head of the Joint Committee on Taxation and the chairman of House Ways and Means Committee - can ask for any individual's tax information for legislative purposes and the secretary of the treasury "shall furnish" the request.
Mnuchin told a House panel that he personally has not had any communications with the president or his top staff about the department's decision on whether to provide Trump's tax returns under a almost century-old law that says the Treasury Department "shall furnish" them when requested by top lawmakers.
Experts disagree, saying nothing prevents him from following a decadeslong tradition of transparency among presidents, though Mr. Trump is digging in for a legal battle over the information.
"While I'm under audit, I won't do it", he added, ignoring that the IRS by law is mandated to release the tax returns of an American if requested by the Chairman of the House Way and Means Committee.
Republican Trump has consistently refused requests by politicians, journalists and others, stating his reason for not doing so is that the returns are under audit.
Federal law allows the Ways and Means and Senate Finance committees and the Joint Committee on Taxation to ask the IRS for the returns of any filer, but some legal scholars say a request requires Congress to have a legislative goal, including general oversight. I said you may leave any time you want and you said 'OK.
"We would not ever ask for the White House's permission on this nor did they give us the permission".More news: Galaxy A80 United Kingdom release, specs and price - Samsung's radical new smartphone REVEALED
Allies of the President have argued that the Democrats have no right to see his returns.
When asked by CNN if he had spoken Rettig in recent days, Mnuchin said, "I speak to the IRS commissioner regularly. They knew that he didn't, and they elected him anyway-which, of course, is what drives the Democrats insane".
"It is being reviewed by the legal departments and we look forward to responding to the letter", he said.
In the letter, Mnuchin references Neal's preparation for the request, writing that "you too have acknowledged the unprecedented nature of the request".
Treasury Secretary Steven Mnuchin and House Financial Services Chair Maxine Waters probably won't be exchanging holiday cards this year after things got a little tense during the Treasury secretary's testimony on Tuesday.
And even if we were able to get our hands on Trump's returns, the likelihood of finding anything criminal is somewhat unlikely.
The passive aggression was visible on both sides, with Waters insisting that Mnuchin had "made an offer" to stay, and Mnuchin suggesting that she was "ordering for me to stay here". I want to be very clear on that. "We are confident that this misguided attempt to politicize the administration of the tax laws will not succeed". "I'm not going to make a specific comment on that, but it would be a good guess". He has frequently promised to release his tax returns once an audit of these returns is completed by the IRS.