A ProPublica and New York Times investigation found that a lengthy IRS audit concluded Donald Trump took the same huge deduction twice. As one of their tax experts put it, “I think he ripped off the tax system.”

From ProPublica:

Former President Donald Trump used a dubious accounting maneuver to claim improper tax breaks from his troubled Chicago tower, according to an IRS inquiry uncovered by ProPublica and The New York Times. Losing a yearslong audit battle over the claim could mean a tax bill of more than $100 million.

The 92-story, glass-sheathed skyscraper along the Chicago River is the tallest and, at least for now, the last major construction project by Trump. Through a combination of cost overruns and the bad luck of opening in the teeth of the Great Recession, it was also a vast money loser.

But when Trump sought to reap tax benefits from his losses, the IRS has argued, he went too far and in effect wrote off the same losses twice.

ProPublica and New York Times reporters explain the complexities of Trump’s dodgy accounting. But a few related, not-so-weedy details stand out: One, the IRS totally missed this apparent scam for years; and two, “The agency’s difficulty in keeping up with Trump’s maneuvers, experts said, showed that this gray area of tax law was too easy to exploit.” But Trump’s case could help close off some of the ways the mega-wealthy game the system, the reporters noted.

Meanwhile, Trump is already facing massive financial liabilities.

From The New York Times:

In recent months, he has been ordered to pay $83.3 million in a defamation case and an additional $454 million in a civil fraud case brought by the New York attorney general, Letitia James. Trump has appealed both judgments. (He is also in the midst of a criminal trial in Manhattan, where he is accused of covering up a hush-money payment to a porn star in the weeks before the 2016 election.)

That’s not counting the millions and millions Trump owes in legal fees.