Moderator Chris Wallace has repeatedly tried to keep Trump from interrupting Biden.

"It's hard to get any word in with this clown," Biden said, "excuse me, this person."

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.

In a heated discussion on tax policy, Biden criticized Trump's trade policies with China which led to the first thinly veiled mention of Hunter Biden on stage.

"He talks about the art of the deal. China's perfected the art of the steal. We have a higher deficit with China now than we did before, we have the highest deficit -- trade deficit with Mexico," Biden said, before Trump interrupted.

"China ate your lunch, Joe. And no wonder your son goes in and he takes out what he takes out, billion of dollars," Trump said, before launching personal attacks on Biden's son, Hunter Biden, and his business dealings while his father was vice president. Hunter Biden has denied any wrongdoing.

"We want to talk about families and ethics? I don't want to do that. I mean his family, we can talk about all night," Biden responded, then said the American people don't want to hear about their families.

Asked about how they would deal with economic recovery, Trump said he would avoid further shutdowns, touted the current economic recovery and credited himself with bringing back college football.

"Our country is coming back incredibly well, setting records as it does it. We don't need somebody to come in and say let's shut it down," Trump said, though Biden said he would not impose a full shutdown as the president suggested.

Biden then took the opportunity to speak directly to American families on Trump's taxes and repeated his mantra that the U.S. "can't fix the economy without fixing COVID."

"The difference is millionaires and billionaires like him in the middle of the COVID crisis have done very well," Biden said. "You folks living in Scranton and Clayton and all the small towns and working-class towns in America: How well are you doing?"

TRUMP'S STATEMENT: "Once you became vice president, (Hunter Biden) made a fortune in Ukraine and China and Moscow and various other places. He made a fortune, and he didn't have a job."

FACT CHECK: While the exact sum of Hunter Biden's foreign business ventures is unclear, ethics experts have broadly taken issue with them -- particularly those in places like Ukraine and China, at a time when his father was fronting U.S. policy there.

Robert Weissman, the president of progressive watchdog group Public Citizen, told ABC News last year, "at absolute minimum there's a huge appearance of conflict … (Joe Biden) should have encouraged his son to not take these positions."

Still, Weissman called Hunter Biden's business activity "orders of magnitude" less troubling than how the Trump family has operated its businesses during the Trump administration.

In an interview with ABC News last year, Hunter Biden said he exercised "poor judgment," but maintained that he made no "ethical lapses."

"I gave a hook to some very unethical people to act in illegal ways to try to do some harm to my father. That's where I made the mistake," he said. "So I take full responsibility for that. Did I do anything improper? No, not in any way. Not in any way whatsoever."

"Did I make a mistake? Well, maybe in the grand scheme of things, yeah," he continued. "But did I make a mistake based upon some ethical lapse? Absolutely not."

In their 87-page report released last week, Senate Republicans concluded that Hunter Biden's overseas endeavors were "awkward" and at times "problematic," but stopped short of identifying any criminal activity on Hunter Biden's part or any wrongdoing on Joe Biden's part.

--ABC News' Lucien Bruggeman