After the Committee had originally requested the tax returns from IRS Commissioner Charles Rettig in April, Mnuchin set his own deadline for May 6, taking the extra time to review with the Justice Department whether he was even legally required to hand over the returns. This move greatly angered Democrats on the Ways & Means Committee, who have repeatedly maintained they have full authority to demand tax returns from Trump and Vice President Mike Pence.
The committee is conducting the review for the purpose of examining the IRS process of auditing presidential tax returns. This conflicts with Trump's claim he cannot release his returns until he is done being audited.
Democrats now have several options before them, including a subpoena for the returns. So far, each request has been voluntary. If Trump administration officials decline to comply with the subpoena, a lawsuit could follow.
Read more: Tax returns show many 2020 Democrats have one financial habit in common
Mick Mulvaney, Trump's acting chief of staff, has said Democrats will "never" obtain Trump's taxes, echoing many of the president's allies who insist that because Trump broke precedent by not voluntarily releasing his returns as a presidential candidate in 2016 and still won the election, the issue is settled in the minds of the public.
Republicans on the Ways & Means Committee have argued that it is an abuse of power to expose individuals' tax returns, including the president. This is despite the fact that Republicans on the same committee revealed the private tax information of a handful of US citizens during a 2014 probe when they were in the majority.
And Trump himself, who has made a concerted effort to deny Democrats various probes into his administration and personal businesses, has repeatedly said he would not reveal his tax returns.