Despite Donald Trump’s protests to the contrary, Congress is on absolutely firm legal ground to obtain Trump’s past tax returns, according to a Pulitzer Prize-winning journalist who wrote a 2016 biography of Trump.

Rep. Richard Neal (D-Mass.), chairman of the House Ways and Means Committee, has made clear that he plans to access Trump’s tax information through the Internal Revenue Service.

Although presidential candidates from both parties have, for decades, released their tax returns for public review Trump refused to do so.

Asked about the House Democrats’ intention to obtain six years of his tax information and make it public, Trump said, “We’re under audit despite what people said and we’re working that out as — I’m always under audit, it seems, but I’ve been under audit for many years because the numbers are big and I guess when you have a name, you are audited. But until such time as I’m not under audit, I would not be inclined to do that.”

When he testified in a public session of the House Oversight and Government Reform Committee in February, former Trump attorney and fixer Michael Cohen challenged Trump’s claims that his taxes are under audit.

Rather, Trump wants to keep his taxes hidden so that tax experts won’t see them and suggest that he be subject to higher taxes and penalties, according to Cohen.

Regardless, Trump’s objection likely sets up a court fight. But in the end, Democrats clearly have the law on their side, said David Cay Johnston, author of the biography The Making of Donald Trump.

“Under a 1924 anti-corruption law, the chairman of the Ways and Means Committee, the Senate Finance Committee or the employee of Congress who is the chief of staff for the Joint Committee on Taxation all have a right to see this,” he said. “The law says the Treasury secretary shall produce not just the tax return but any tax return information. That means if they have copies of the books and records of Donald Trump’s companies, transaction records, audit notes, audit notices, many other things … “