After paying $91,000 in 2016, Biden's a year ago as vice president in the Obama administration, the Bidens paid $3.7 million to the government in 2017, largely because of income from book deals.
The Bidens reported receiving income from several sources, including Northern Virginia Community College, where Dr Biden has worked as an English professor, and the University of Pennsylvania, where Mr Biden established a center for diplomacy after the end of the Obama administration.
Watch the debate live at nzherald.co.nz from 2pm.
The Biden campaign released the candidates' returns shortly after Mr. Trump's team said Mr. Biden refused a request to have a third party inspect the candidates' ears before Tuesday's debate.
New York Giants adding Devonta Freeman on 1-year, $3 million deal
The 23 year-old ran for over 1,000 in his first two seasons, and was considered a cornerstone of the franchise. The Falcons let him walk as a free agent this offseason and instead signed Todd Gurley .
Trump has called the reports "fake news" yet still refuses to release his returns himself.
The returns will be the 22nd year of returns that Biden has publicly released and the 15th year for Harris. Kamala Harris, and her husband, Doug Emhoff, also released their 2019 returns Tuesday.
As per the Commission on Presidential Debates, the topics for the first debate include "The Trump and Biden Records", "The Supreme Court", "Covid-19", "The Economy", "Race and Violence in our Cities" and "The Integrity of the Election".
A longer, more formal preparation session was expected once he arrives in Cleveland.
While Trump is itching to go on the offence against Biden, some aides have encouraged him to adopt a more measured tone - believing that in many ways the debates are more about Trump vs himself than Biden.