Michael Cohen's recent public congressional testimony was a startling moment in recent history. His allegations that Donald Trump routinely evaded taxes and committed other financial fraud should result in an immediate request to the Treasury to turn over President Trump’s business and personal tax returns.

According to Cohen, Trump falsely inflated his assets to get bank loans, then deflated them to evade taxes. Cohen noted that Trump abused his charitable trust, reimbursing a straw purchaser of a Trump portrait costing $60,000 and accepting a $150,000 payment for a speech, which may have been done to avoid taxes. And Cohen testified that Trump may have even written off hush payments to his former mistresses.

The chairman of the House Ways and Means Committee, on which I serve, has the power right now to obtain Trump’s tax returns, including those of his many businesses and trusts. Under 26 U.S.C. § 6103(f), all it takes is a letter to the Treasury secretary. I’ll deliver the letter myself if necessary. That’s how eager I am—after more than two years of stonewalling, broken promises, phony excuses, and congressional dereliction under Republicans —to finally get the truth about Donald Trump’s taxes.

Trump is the first president in more than 40 years not to disclose any information about his taxes. And never has a president’s finances required such a thorough review. Trump, the only international businessman to ever serve as chief executive, has investments all around the world and continued to pursue them even as he was running for president. These global entanglements would make an octopus dizzy and pose unprecedented conflicts of interest with his official duties.

Trump can’t claim he wasn’t warned about the political implications. Walter Shaub, the director of the U.S. Office of Government Ethics, repeatedly instructed Trump that his failure to divest himself from his family’s myriad businesses would pose nightmare conflicts of interest. Trump ignored Shaub’s warnings.

Among the problematic nations with whom Trump has pursued investments—and whose nationals have done substantial business with him—are Russia and Saudi Arabia. In his official dealings with these autocratic regimes, Trump has shown a striking deference that stands in disturbing contrast to the defiant stance of leaders of other Western countries and political leaders of both parties here in the United States.

Trump’s potential conflicts aren’t just international. Steps from the White House sits a Trump luxury hotel frequented by Washington power players. How many lobbyists are booking its $500 rooms and ordering its $100 cocktails in hopes of currying favors with the innkeeper, who also happens to be president of the United States?

In addition to finding out what conflicts may exist between their president’s financial interests and official duties, the American people have a right to know if their president is a tax cheat. Last October, the New York Times published an exhaustively researched report detailing a pattern of shady tax dealings by the Trump family going back half a century, including instances of what the paper declared to be “outright fraud.” Donald Trump was an active participant in many of these schemes. (This was a problem for Richard Nixon too: when he finally released some of his returns in 1973, investigators found he owed approximately half a million dollars in back taxes.)

Following excellent questioning from Reps. Jimmy Gomez (D-Calif.) and Alexandria Ocasio-Cortez (D-N.Y.), Cohen’s testimony in the Oversight and Reform Committee corroborated the pattern described by the Times. The newspaper discovered that Trump’s father had undervalued assets in order to evade hundreds of millions of dollars in gift and estate taxes. Like father, like son: Mr. Cohen said that Trump had a habit of undervaluing his real estate holdings to evade property taxes.

But the phony valuations apparently go both ways. A palatial Trump property outside New York City is valued, by public records and Trump’s own government financial disclosure documents, at between $20-50 million. But when Trump was trying to get a bank loan to buy a professional football team, Trump claimed it was worth almost $300 million. Lying on a bank loan application is a crime.

Trump, a self-proclaimed billionaire, has responded with pride to accusations that he’s gone years without paying any federal income taxes. According to Cohen, Trump even told his former attorney “that he could not believe how stupid the government was for giving ‘someone like him’” a $10 million IRS tax refund. Well, it’s long past time to see if the American people agree. But first we need the facts.

We need to know if the president has illegally evaded taxes or unethically avoided them by exploiting special breaks in the law. If the latter, we can even use Trump’s own case to help identify and close those loopholes.

My Republican colleagues questioned Mr. Cohen’s reliability as a witness. That’s all the more reason for them to join Democrats in trying to unearth the best evidence of whether Mr. Cohen—and all the other sources and investigators who’ve leveled similar charges—are telling the truth about Donald Trump’s financial conduct. We need to see Trump’s tax returns—including those of his business entities — and we need to see them now.

Rep. Bill Pascrell represents the 9th District of New Jersey and serves on the House Ways and Means Committee.