Former Vice President Joe Biden, who has raked in millions since leaving office, released his financial disclosure form as well as three years of tax returns Tuesday.

The documents showed that Biden and his wife, Jill, made more than $11 million in 2017 before taxes and made more than $4.5 million in 2018 before taxes. Biden's campaign said that the vast majority of that income ($10,048,739 in 2017 and $3,236,764 in 2018) derived from payments to the couple for the writing of two books: Joe's “Promise Me, Dad” and Jill's “Where the Light Enters,” as well as paid speaking engagements.

Biden’s first book, an account of his son Beau’s death from cancer, topped bestseller lists in 2017.

Biden, who was never one of the wealthier members of Congress during his decades as a senator, has seen his fortunes turn considerably since the end of Obama administration.

The couple's earnings from the books and speaking engagements were paid through so-called S-Corporations, which the campaign described as “a common method for taxpayers who have outside sources of income to consolidate their earnings and expenses.” The campaign also said Joe and Jill Biden employed staff and engaged contractors to support their work through their S-Corporations, known as “CelticCapri” and “Giacoppa.”

Joe Biden also earned more than $775,000 over 2017 and 2018 as a professor and namesake of the University of Pennsylvania’s Penn Biden Center for Diplomacy and Global Engagement in Philadelphia, while Jill Biden earned more than $90,000 in each of the past two years as a professor at Northern Virginia Community College.

During a four-decade political career, Biden brought home little more than his government salary.

The leading Democrat in the 2020 presidential race, who has now made public the last 21 years of tax returns, has moved into a sprawling mansion outside Washington since he left the White House.

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“Middle-Class Joe” more recently has resided in a 12,000-square-foot home in McLean, Va., that came complete with “five bedrooms and 10 bathrooms, marble fireplaces, a gym and a sauna,” The Washington Post reported last month.

The Bidens have been renting the home from multi-millionaire Mark Ein.