White House press secretary Sarah Sanders said Sunday that she doesn't think congressional Democrats are "smart enough" to review President Donald Trump's tax returns should they succeed in obtaining the documents.
But in the letter, Mr Neal told IRS Commissioner Charles Rettig: "None of the concerns raised can legitimately be used to deny the committee's request".
US federal law clearly details that when the chairman of the US House Ways and Means Committee provides a request in writing for any US citizen's tax returns - even a sitting US president - the US Treasury, now headed by Trump appointee Steve Mnuchin, "shall furnish" the documents. The question, it seems, will be whether the Trump-packed courts will protect him and his administration from that oversight.
On Wednesday, Mr Mnuchin said the Treasury was handling the request and that a deadline set for that date would be missed, citing possible constitutional issues. "We'd love to work with you guys to figure out exactly the best way to transport these people were here illegally and unlawfully and into your communities and your districts and your states".
A top House Democrat on Saturday ratcheted up his demand for access to President Donald Trump's tax returns, telling the IRS that the law clearly gives Congress a right to them.
"Even if Ways and Means had a legitimate committee objective for requesting the President's tax returns and return information, that goal is not driving Chairman Neal's request", he wrote. Being under audit is no legal bar to anyone releasing his or her returns.
It's also unclear how long the immigrants would stay in these cities because they are required to provide an address to federal authorities, typically of a family member, as a condition of their release. And after the November midterm elections, Trump claimed at a news conference that the filings were too complex for people to understand.
Richard Neal's deadline for the United States government to hand over the tax records is on 23 April.
Trump appears prepared to fight this to the Supreme Court.
Numerous administration's plans regarding asylum seekers have quickly been challenged in the courts as not legal or constitutional, including banning those who cross between ports of entry from claiming asylum at all, as well as a plan to have ever-increasing numbers wait in Mexico before their date in immigration court, which can take months or even years. Some Treasury-watchers observe that Mnuchin's decision to consult with the Justice Department could suggest that Treasury lawyers believe Neal has a legal right to Trump's returns.
Nadler, who has been one of the top Democrats in Washington pushing for a full release of Special Counsel Robert Mueller's report into possible collusion between the 2016 Trump campaign and Russian Federation, has feuded with Trump for more than 30 years, according to Rolling Stone magazine.
Congressional Republicans and Trump's personal attorney, William Consovoy, have argued Democrats' request risks weaponizing the IRS for partisan political gain, with Consovoy calling it a "gross abuse of power".