US Democratic presidential nominee Joe Biden has released his tax returns showing he and his wife paid more than $US346,000 ($A$485,000) on income earned in 2019.

It comes hours before his first debate with US President Donald Trump who was earlier this week exposed by the New York Times as having paid just $US750 ($A1053) in federal income taxes in 2016 and 2017.

Mr Biden’s taxes showed that he paid back almost a third of the money he made in 2019, with his deputy campaign manager Kate Bedingfield saying “this is a historic level of transparency”.

Mr Biden got back nearly $US47,000 from the $US346,000 he and his wife, Jill, paid in federal taxes and other payments for 2019.

They said the refund was the result of overpaying the government on the income earned, which neared $US985,000.

• Read: What to watch when Donald Trump debates Joe Biden for first time

Ms Bedingfield urged the President, who long sought to keep his personal financial records secret, to “release your tax returns or shut up”.

But even during a Twitter tirade on Tuesday where he claimed to have “paid many millions of dollars in taxes”, Mr Trump did not produce any evidence to show the leaked records by The Times were “nonsense”.

Ms Bedingfield said she hoped Mr Biden’s tax disclosure would “give the American people faith once again that their leaders will look out for them and not their own bottom lines”.

With more than a million American voters already casting early ballots and time running out to change minds or influence those undecided, the stakes are enormous as the two White House candidates take the stage five weeks before the November 3 election.

The 90-minute debate, with a limited and physically distanced in-person audience because of the pandemic, will begin at 9pm EDT (11am AEST on Wednesday) at Case Western Reserve University in Cleveland.

It is the first of three scheduled debates.

-with AAP