After the two presidential candidates exchanged a few jabs early on the debate stage on Monday, the night’s first haymakers came, predictably, when the sensitive subject of Donald Trump’s tax returns came up. The G.O.P. nominee was quick to try to turn the question on his rival Hillary Clinton, but missed his killshot.

With less than two months to go until American voters cast their ballots in November, the Republican standard-bearer has not yet released his tax filings, breaking the precedent set by every presidential candidate for the past four decades. On Monday night, NBC’s Lester Holt asked Trump if he had any intention of making his tax filings public. In response, the real-estate mogul fell back on the well-worn argument that an ongoing I.R.S. audit has prevented him from releasing his tax returns, but added a challenge to Clinton: he will release his tax returns, he said, if she releases the 33,000 e-mails that were deleted on the private e-mail server she maintained while secretary of state.

But Trump’s attack on Clinton quickly backfired. The Democratic nominee jumped on the opportunity to raise issue with Trump’s decision not to release his tax returns. Clinton pulled a page that was downright Trumpian: raising a number of the theories that have circulated in recent months as to why the New York businessman won’t show his returns. Perhaps they would reveal that his net worth is not great as he claims, she wondered, or show potentially questionable business relationships he may have or that he has enjoyed an incredibly low tax rate for years. She then took it one step further and slammed Trump for declaring bankruptcy six times and dubbing himself the “King of Debt.”

Holt did eventually bring the focus back to Clinton’s e-mails, but the former secretary of state escaped the probe relatively unscathed. Despite her e-mail scandal having dogged her campaign throughout the election Trump’s subsequent rebuttal to Clinton fell flat. “As far as my tax returns, you don’t learn that much from tax returns,” he argued. Before adding that his finances are “very underleveraged” and insisted that he didn’t mean that “in a braggadocious [sic] way.”