Hours before his first debate with US President Donald Trump, Democratic presidential nominee Joe Biden has released his 2019 tax returns and his campaign called on Trump, who has come under fire for not releasing his returns, to do the same.
Biden, due to share the stage with Trump on Tuesday evening local time in Cleveland, took the step two days after the New York Times reported that Trump paid just $US750 ($A1053) in federal income taxes in 2016 and 2017 - and none in 10 of the previous 15 years - after reporting years of heavy losses from business enterprises.
Trump had long sought to keep his personal financial records secret.
Biden's taxes showed that he and his wife Jill paid more than $US346,000 in federal taxes and other payments for 2019 on an income of nearly $US985,000 before seeking a refund of nearly $US47,000 they said they had overpaid the government.
"This is a historic level of transparency meant to give the American people faith once again that their leaders will look out for them and not their own bottom lines," Biden's deputy campaign manager, Kate Bedingfield, said on a call with reporters.
"Mr President, release your tax returns or shut up," Bedingfield added.
With more than a million 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.