Mr Obama's books have been on best-seller lists for years
US President Barack Obama and his wife Michelle earned $2.66m (£1.78m) in 2008, according to annual tax returns released by the White House.
The figures also show the president and first lady gave $172,050 to various charities and paid $933,000 in taxes.
Most of the money came from royalties for sales of the president's books.
Mr Obama has written two non-fiction books, an autobiography and a political manifesto, which have remained in the best-seller lists for several years.
The White House said Mr and Mrs Obama filed their mandatory annual tax returns just in time to make the 15 April deadline.
Together, they declared gross earnings of $2,656,902, "the vast majority" of which came from sales of Mr Obama's books.
Mr Obama's political manifesto, The Audacity of Hope: Thoughts on Reclaiming the American Dream, was published in 2006 and has remained on the New York Times best-seller list for 67 weeks.
His autobiography, Dreams From My Father, has been on the list for 142 weeks and is currently at number eight.
As well as the $855,323 paid in federal taxes and $77,883 in state income taxes, the Obamas gave 6.5% of the income to charity.
The largest donations were $25,000 each to the humanitarian organisation Care and the United Negro College Fund, which provides assistance to US students from ethnic minorities.
The Obama's income is down from their 2007 tax return, where they declared $4.2m in gross earnings.
Vice-President Joe Biden and his wife Jill have also filed their tax returns, declaring $269,256 in pre-tax earnings.
The US president earns a statutory salary of $400,000, while the vice-president's salary is about $220,000.
US families have an average annual household income of about $50,000.