Biden accused Trump of running the "most corrupt government in the history of the United States of America." and touted his release of more than two decades' worth of his income tax returns.
"You want to talk about corruption? I have released 21 years of my tax returns," he said.
"I entered as one of the poorest men in Congress, left one of the poorest men in government and Congress and as vice president. I made no money while I was in there, other than my salary. Mr. President, even Richard Nixon released his tax returns. Mr. President, release your tax returns or shut up.”
Trump broke with decades-long precedent during the 2016 presidential campaign by declining to make his past tax returns public, claiming that he can't do so because he is under audit.
Biden has maintained that he never talked with his son about his Ukrainian business dealings and said he didn't have any regrets about not admonishing his son from taking a job with an energy firm in the country.
Trump previously requested that Ukraine investigate the Bidens, prompting House Democrats to accuse him of trying to influence the 2020 election. Rudy Giuliani, Trump's attorney, also urged Ukraine to investigate the Bidens.
During Tuesday's Democratic debate, Biden defended his son and argued that he did "nothing wrong."
“My son did nothing wrong. I did nothing wrong,” he said. “I carried out the policy of the United States government, which was to root out corruption in Ukraine and that’s what we should be focusing on.”
Fox News' Brooke Singman contributed to this report.