On April 13, Neal gave the IRS a "hard deadline" until April 23 to provide him with the tax returns after Steven Mnuchin, the Treasury Secretary, said last week that he could not meet an earlier deadline because he needed to study the lawfulness of the request.
Trump, who declined to provide his tax returns while running for President, continues to cite an ongoing audit as the reason he cannot release the documents, despite no rule or law that prevents him from doing so.
Neal used an obscure provision of the tax code to request the returns, which he said his committee needs in order to evaluate the policy of automatic audits of presidential tax returns.
Trump and his defenders argue that the request is being driven by politics and represents presidential harassment.
Consovoy said on Monday that the legal rationale behind Neal's dismissal of the Treasury Department's concerns was wrong.
"Congress's motives do matter under the Constitution," Consovoy wrote in the letter, arguing that the request for Trump's tax information does not serve any legislative purpose.
He noted that House Republicans on the Ways and Means Committee concluded that a request for Trump's tax returns was not a legitimate use of their oversight powers.