Court documents and other public records show that Donald Trump paid no income tax in 1978, 1979, 1992, and 1994. PHOTOGRAPH BY ANGELO MERENDINO / GETTY

The Washington Post’s David A. Fahrenthold is rightly getting a lot of attention for his stellar reporting on Donald Trump’s charitable giving, or the lack thereof. Fahrenthold and his colleagues have spent more than six months contacting hundreds of charities that Trump claims to have given money to through his family charity, the Donald J. Trump Foundation.

“So far, the Post’s search has turned up little,” Fahrenthold and Danielle Rindler wrote in August. “Between 2008 and this May—when Trump made good on a pledge to give $1 million to a veterans’ group—its search has identified just one personal gift from Trump’s own pocket.” As Fahrenthold and Rosalind S. Helderman had already revealed, in April, many of the donations that Trump claimed to have made turned out to be gifts in kind from his businesses, such as free rounds of golf for charity auctions.

Fahrenthold’s latest revelation, which the Post published on Sunday, was that Trump has “found a way to give away somebody else’s money and claim the credit for himself.” Apparently, the Trump Foundation raises money from other charities, and from individuals with whom Trump has done business. Then it gives away the money with Trump’s name on the check. The last donation Trump made to his charity, Fahrenthold reported, came in 2008. Since then, nada.

Which brings us back to an interesting question: Is it possible that Trump is also paying nothing in income tax? A number of journalists and tax experts who have looked at Trump’s finances think it may well be.

Last month, James Stewart, a Times columnist, wrote about Trump’s taxes, and compared him with Mitt Romney, who was criticized in 2012 for paying just $4.9 million in federal income tax. “No one should be surprised, though, if Donald J. Trump has paid far less—perhaps even zero federal income tax in some years,” Stewart wrote. “Indeed, that’s the expectation of numerous real estate and tax professionals I’ve interviewed in recent weeks.” These experts explained to Stewart that the federal tax code is so generous to real-estate developers—so stuffed with deductions, credits, and loopholes they can exploit—that it may well have allowed Trump to bring his taxable income down to nothing, or next to nothing. Which might help explain why he is so reluctant to release his tax returns.

To be clear, the latest revelations about the Trump Foundation didn’t contain any explicit information about Trump’s personal tax returns. (Fahrenthold himself has pointed out that the unavailability of Trump’s returns has made it a lot harder to track his charitable activities.) But the two stories could well be connected. Perhaps one of the reasons that Trump didn’t give any money to his foundation was that he didn’t need any charitable deductions to reduce his tax bill—because it was already zero, or close to it.

We know for sure that Trump does everything he can to avoid sending money to the I.R.S. In May, he told ABC News’s George Stephanopoulos, “I fight very hard to pay as little tax as possible.” We also know that one way wealthy people reduce their tax bills is by making contributions to qualified charities, contributions that are usually fully deductible. Surely a man as determined and tax-averse as Trump, in seeking to reduce his tax obligations, would exploit every option that the tax code offers, including this very obvious one. Unless, of course, he didn’t need to.

“If you have little or no taxable income, then why would you make a charitable contribution?” David Cay Johnston, a veteran investigative journalist who recently published a biography of Trump that includes extensive discussions of his financial affairs, told me on Thursday. “The fact he hasn’t made any contributions to his foundation since 2008 is another strong indication he doesn’t pay income taxes.”

Cay Johnston was the tax reporter for the Times from 1995 until 2008, and in 2001 he won a Pulitzer Prize for his coverage of the loopholes in the federal tax code that favor corporations and rich people. He pointed out that court documents and other public records show that Trump paid no income tax in 1978, 1979, 1992, and 1994. More recently, Cay Johnston said, New York State tax records show that Trump has several times received a type of tax rebate that is restricted to property owners who report taxable income of less than half a million dollars, known as a STAR credit. “It is likely that Trump has not paid any income tax since 1978, or maybe a little bit in a couple of years,” Cay Johnston told me.

Of course, it’s still possible that Trump gave money to charities directly and privately, rather than through the Trump Foundation. That is what he claims to have done, and if this is true he could have deducted those donations from his income for tax purposes. But neither Fahrenthold nor Cay Johnston has been able to find much trace of this type of philanthropy, either. “There is absolutely no evidence that he has given these charitable gifts,” Cay Johnston said. “Can you imagine Donald Trump making anonymous gifts to anybody?”

To be sure, the theory that Trump hasn’t paid any income taxes is just speculation. But it’s informed speculation based on knowledge of the tax laws and inspection of the limited information about Trump’s finances that is publicly available. And, of course, if Trump wants to put an end to this type of theorizing, he knows how to do it: put out those returns.

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