What Is Donald Trump Hiding?

The latest revelations about President Trump’s past tax reports underscore the importance of examining his more recent returns.

The disclosure of Mr. Trump’s tax returns could also help to verify, or falsify, a range of assertions that Mr. Trump has made about his own life — stories that he used to build support for his candidacy and continues to use to build support for his policies.

One straightforward fact-check: Mr. Trump repeatedly said he would not benefit from the tax cuts passed by Congress in 2017. He said that he would be a “big loser” and that the plan “is going to cost me a fortune.” The claim is absurd on its face. Virtually every major analysis of the tax cut has shown that wealthy people like Mr. Trump are the primary beneficiaries. But despite Mr. Trump’s best efforts, facts remain stubborn things with special power, and the release of his tax returns would allow a precise calculation of just how much money the president put into his own pocket.

Reporting on Mr. Trump’s financial past by Times reporters, including David Barstow, Susanne Craig and Russ Buettner has already undermined the president’s confected image as a hugely successful businessman. In a piece published Tuesday evening, Ms. Craig and Mr. Buettner reported Mr. Trump “appears to have lost more money than nearly any other individual American taxpayer” year after year in the late 1980s and the early 1990s. Mr. Trump has long said he suffered setbacks during the recession in the early 1990s, and then bounced back to rebuild his fortunes. But tax records and other sources show Mr. Trump lost big during the boom years of the late 1980s.

Far less is known about Mr. Trump’s more recent financial dealings. His federal disclosures provide estimates of revenue rather than profits: In 2017, for example, Mr. Trump reported that his Irish golf business had revenues of $14 million, while a separate report to Irish regulators said the business lost about $2 million. For most of Mr. Trump’s ventures, there is no public account of the bottom line.

The tax returns could also be used to verify the accuracy of the financial disclosures, or at least to check whether Mr. Trump’s returns are consistent with those disclosures.

Mr. Trump, for example, omitted from his 2017 disclosure his obligation to repay Michael Cohen for the $130,000 payment Mr. Cohen made on his behalf to the pornographic film actress Stormy Daniels. That was before The Wall Street Journal first reported the debt. The following year, Mr. Trump reported on his disclosure that he had repaid Mr. Cohen.

And the returns could shed light on some mysteries. In the decadebefore he became president, Mr. Trump went on a $400 million shopping spree, paying cash for real estate around the world — a binge first reported by The Washington Post. It was a marked break from Mr. Trump’s longstanding habit of using other people’s money, and it remains unclear where Mr. Trump got the money, and why he decided to spend it.

The returns also could help to clarify whether Mr. Trump continues to cheat on his taxes. The Times has previously reported that Mr. Trump engaged in fraud to avoid taxation during the 1990s. In requesting Mr. Trump’s tax returns, the House has said it seeks to evaluate whether he is being properly audited by the Internal Revenue Service, which audits all presidential returns as a matter of policy. It has asked for the last six years of the president’s personal tax returns — the period likely still subject to an I.R.S. audit — and tax information for eight of Mr. Trump’s businesses.

The congressional effort to obtain Mr. Trump’s returns is a second-best solution. The House committee would be able to evaluate the information, but not to share the returns with the public. Similarly, a bill passed by the New York State Senate on Wednesday would allow New York to release Mr. Trump’s state tax returns to select congressional committees, but not to the public.

The best answer remains for Mr. Trump to keep his promise and release his returns voluntarily. But unless and until he does so, Congress can and must force the issue.