Biden, wife made over $US15m in two years

Former US Vice President Joe Biden and his wife, Jill, earned more than $US15 million in the two years after Biden left government in early 2017.

The majority of their income came from speaking engagements and payments for two books written by Biden, a top contender for the 2020 Democratic presidential nomination, according to tax records released by his campaign.

According to federal and state tax returns, the Bidens earned about $US11 million in 2017 and $US4.58 million in 2018. About $US13.2 million of that was attributable to book payments.

Biden earned more than $US775,000 in salary as a professor at the University of Pennsylvania in 2017 and 2018.

The Biden campaign released a financial disclosure form mandated for presidential candidates, which provided details of his speaking engagements and book events from Jan. 1, 2018, to May 31, 2019.

The form shows that Biden, who likes to refer to himself as "Middle-Class Joe" on the campaign trail, was regularly paid a six-figure fee for speaking events, many at private universities such as Drew University, where he was paid $US190,000, and Vanderbilt University, where he received $US180,000.

Most of Biden's book events and speaking events took place at theatres and auditoriums, but two events were handled through Creative Artists Agency's Premium Experience - which specialises in "corporate hospitality" events. For a CAA book tour event in 2017, Biden was paid $US234,000.

According to the couple's tax returns, they paid $US3.7 million in federal taxes in 2017 and donated about $US1 million to charity. In 2018, they paid $US1.5 million in federal taxes and donated about $US275,000 to charity.