Trump was asked about the request during a White House meeting with military leaders.
In a letter to IRS Commissioner Charles Rettig, Neal said the returns are necessary for Congress to determine whether the IRS is properly enforcing tax laws "in a fair and impartial manner". "Oh, usually it's 10 so I guess they're giving up".
Trump says: "We're under audit despite what people said".
The president again vowed to release his tax returns in a January 2016 interview with NBC's "Meet the Press," telling host Chuck Todd, "We're working on that now".
Neal requested Mr. Trump's individual tax returns for the years 2013 to 2018, as well as a statement stating whether the return is or was subject to an audit and, if so, the reasons why.
The Democrat-controlled House is wasting no time in getting to the bottom of whatever it may be that President Donald Trump could be hiding.
"Is that all?" Trump said when asked about the six years of returns.
As Democrats tied the bows on their most aggressive week of oversight since taking back the House majority in January for the first time in almost a decade, their Republican counterparts accused them of impeding the president's agenda and ability to work with House Democrats on policy solutions.
A Democratic aide said the committee selected a manageable number of business entities that provide a vital window on Trump's business activity.
As the IRS is part of the Treasury Department, it is unclear whether Treasury Secretary Steven Mnuchin will release the tax documents to the House panel.
Mr Neal's announcement follows a months-long debate within the Ways and Means Committee about how and when to issue the request for Mr Trump's tax returns.
Both the president and vice president automatically have their tax returns audited each year as an attempt to bolster public trust.
Members also wanted Mr Neal to expand any request to be not just personal returns, but also business returns.
"My actions reflect an abiding reverence for our democracy and our institutions, and are in no way based on emotion of the moment or partisanship".
The request is likely to set up a lengthly battle between the committee and Trump, who declined to publicize any of his recent returns during his presidential campaign and hasn't shown any since he took office. Chuck Grassley (R-Iowa) has said he would also want to review the returns if Democrats obtain the reports.
Democrats on the House Intelligence and Financial Services committees will be keen to comb those returns as they dig into the president's personal finances and ties to foreign government and entities for their own, separate wide-ranging investigations. "But doing it for political purposes is not legitimate".