President Obama and Michelle Obama greet people while visiting Section 60 at Arlington National Cemetery on May 27 in Arlington, Va. (Mark Wilson/Getty Images)

President Obama and first lady Michelle Obama made slightly more than half a million dollars in 2013, according to the president's just-released tax return.

The Obamas made just more than $503,000 and paid about $98,000 in taxes.

About $104,000 of the Obamas' income came from the president's books, which have been a chief source of income during his presidency. Obama's salary is just less than $400,000.

The Obamas' income has dropped steadily in recent years, from $790,000 in 2011 to $662,000 in 2012 and now half a million in 2013. A big reason is that he is earning less money from his books.

Vice President Biden and his wife, Jill Biden, meanwhile, made a little less than $409,000 in 2013. They paid $96,000 in taxes.

Jill Biden made $24,000 from her book writing.

Here is the Obamas' return:

President Obama's 2013 Tax Returns

And here is the Bidens':

Vice President Joe Biden's 2013 tax return