Updated

President Obama and first lady Michelle Obama had a combined income of $789,674 in 2011 but paid a lower tax rate than the president's secretary, who made less than $100,000, the White House confirmed Friday.

The Obamas paid an effective rate of 20.5 percent. White House aides would not reveal presidential secretary Anita Breckenridge’s tax rate but confirmed it was higher than the first family's rate. Breckenridge earned $95,000 last year.

The Obamas' rate is less than the 30 percent the president wants millionaires to pay under his proposed Buffett Rule.

“The president’s secretary pays a slightly higher rate ... than the president on her substantially lower income, which is exactly why we need to reform our tax code and ask the wealthiest to pay their fair share,” White House spokeswoman Amy Brundage told Fox News.

The release Friday of the tax returns for the president and the family of Vice President Joe Biden came on the same day in which the Obama campaign in Chicago attacked likely GOP-presidential nominee Mitt Romney for, so far, releasing only his most recent tax returns.

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“Did he pay a lower income tax rate than the 13.9 percent he paid in 2010 and is that why he opposes the Buffett Rule to ensure millionaires don’t pay less taxes than middle-class families?” Obama campaign manager Jim Messina asked in a press release from the campaign.

Later in the day, a Romney spokeswoman said Romney has file for an extension and would make public his 2011 returns before the November election.

The Obamas paid more than $160,000 in federal taxes last year.

The president's 2011 federal income tax return shows reported adjusted gross income of about $790,000 last year. About half of the first family's income is the president's salary. The White House says the rest comes from sales of Obama's books.

Click here to see President Obama's tax return.

The White House released a copy of the president's tax return, which also shows charitable donations of more than $172,000.

Obama is donating after-tax proceeds from his children's book to the Fisher House Foundation. The charity helps veterans and military families receiving medical treatment.

For Biden and his wife, Jill Biden, this year's tax return looks almost identical to last year's.

Returns for 2011 released by the White House show the Bidens paid $87,900 in federal taxes on adjusted gross income of $379,035.

Click here to see Vice President Biden's tax return.

Their income was $143 below their 2010 return, but their tax bill was $1,274 higher. In both cases, the effective tax rate was just over 23 percent.

On the latest return, the Bidens listed $5,540 in donations to charity.

Most of the couple's income came from the vice president's salary of $225,521 and Jill Biden's wages of just over $82,000 for teaching at Northern Virginia Community College.

Ed Henry contributed to this report.