President Obama released his 2011 tax returns, while his Republican opponent Mitt Romney filed Friday for an extension, potentially providing Democrats an issue on which to attack him.

The Obamas’ returns showed $789,674 in income, both from the president’s salary and royalties from the sales of his books. They paid $162,074 in federal income taxes, about 20.5 percent, and donated 22 percent of their income to 39 different charities.

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After Obama’s release, Romney’s campaign announced he would file an extension, meaning his returns may not be public for months. In January, the Romney campaign released his 2010 returns, which showed income of $ 21.6 million and an effective tax rate of 13.9 percent. Romney’s team released an estimate for 2011 that suggested he would pay 15. 4 percent in taxes on more than $20 million in income.

Obama’s campaign is pressing Romney to release his returns from previous years, as other presidential candidates have done, but he has so far refused.