» Does he or doesn’t he? What we know about Trump taxes,

His remarks in debate cast doubt on what he pays.

Hillary Clinton was waiting for this one on Monday night: a line of questioning about Donald Trump’s refusal to release his income tax returns.

And she pounced, listing off theories of why Trump would want to keep his tax information out of the public eye.

Perhaps he did not want to reveal foreign business interests. Maybe he had not been so charitable, or was not as wealthy, as he claimed. But it was another possibility — that Trump had not been paying income taxes — that set off a curious response from him that sounded a lot like an admission.

“That makes me smart,” Trump said when Clinton brought up how returns dating from more than two decades ago showed he had paid no taxes then.

When she suggested a short time later that Trump was still paying no federal taxes and had not done so for many years, Trump offered another retort: “It would be squandered, too, believe me.”

For someone as wealthy as Trump to pay no federal income taxes would be remarkable, all the more so given the doctrine of progressive taxation long embraced by the United States.

Even before Monday’s debate, it was known that Trump had not paid any income taxes in certain years, based on paperwork he filed with New Jersey casino regulators and other instances in which his taxes appeared in public records. But those records are all at least 25 years old.

Tax experts say real estate developers like Trump have access to a range of tax breaks, meaning it would be possible for him to pay minimal taxes even as his wealth expanded. Others have suggested that major losses in his businesses in the 1990s may have sheltered him from paying taxes for years. A business loss in one year can be used to offset income in future years, reducing or even eliminating someone’s tax burden.

When Mitt Romney was the Republican nominee in 2012, his return from the year before revealed his effective tax rate had been 14 percent, strikingly low for someone of his wealth. He had legally benefited from the lower tax rate on so-called carried interest, which Democrats in Congress have tried unsuccessfully to reverse. Romney has been among those calling on Trump to release his taxes.

Clinton and her husband, former President Bill Clinton, have released their 2015 returns, showing that they paid $3.6 million in federal taxes on adjusted gross income of $10.6 million, for a 35 percent tax rate. The Clintons have released taxes dating to 2007 for this campaign, in addition to taxes that they have made public during earlier campaigns.

Those disclosures allowed Hillary Clinton to seize on the issue to draw a contrast with Trump at the debate. She said that if Trump had not paid taxes, that meant “zero for troops, zero for vets, zero for schools or health.”

“For 40 years, everyone running for president has released their tax returns,” she said. “You can go and see nearly, I think, 39, 40 years of our tax returns — but everyone has done it.”

Trump responded, as he has repeatedly, he is not releasing his tax returns because they are under a routine audit from the Internal Revenue Service. But IRS officials have said he is under no obligation to keep his forms secret.

In the “spin room” after the debate, Trump disputed any suggestion that he had admitted to not paying income taxes.

“No I didn’t say that at all,” he said. “I mean, if they say I didn’t, I mean, it doesn’t matter. I will say this: I hate the way our government spends our taxes.”

Trump also asserted, “Of course I pay federal taxes.”

With the race in its final phase, there is substantial interest among voters in Trump making his taxes public, according to polls.