Amid bombshell reporting in the New York Times on the past two decades of Trump's taxes, Wallace put the first question to the president.
"Is it true that you paid $750 in federal income taxes?" Wallace asked.
"I paid millions of dollars in taxes," Trump responded. "Millions of dollars of income tax."
But the president never fully answered if that was federal income tax.
Trump paid just $750 in income taxes in 2016, the year he ran for president, and in 2017, his first year in the White House, according to the Times report.
Biden, meanwhile, paid nearly $288,000 in federal income taxes last year, according to returns he released just hours before his Tuesday night debate, an effort to draw a sharp contrast with the revelations about Trump's tax returns.
Democrats said if the president is upwards of $400 million in debt as the New York Times has reported, he poses a national security threat to the country.
Wallace pressed on, asking "Mr. President, I'm asking you a question. Will you tell us how much you paid in federal income taxes in 2016 and 2017?
"Millions of dollars," Trump replied.
The president then blamed Biden for the tax codes since Biden has worked for so long in Washington.
"I'm going to eliminate the Trump tax cuts," Biden said.
"You are the worst president America has ever had," Biden continued.
"Let me just say, I've done more in 47 months than you've done in 47 years, Joe," Trump replied.