President Barack Obama's secretary paid taxes at a higher rate than he did in 2011 despite having a "substantially lower income," the White House said Friday, casting the disparity as an argument for Congress to adopt the so-called "Buffett Rule."

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"The president's secretary pays a slightly higher rate this year 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," Amy Brundage, a White House spokeswoman, told Yahoo News by email.

Obama on Friday released his 2011 tax filings, showing that he paid $162,074 in total taxes on adjusted gross income of $789,674, an effective rate of 20.5 percent. The first couple paid $31,941 in Illinois income tax. Obama's secretary, Anita Decker Breckenridge, made $95,000 in 2011, according to the White House's public report on pay in the West Wing.

The president has been making the case for the Buffett Rule legislation that would raise taxes on the very richest Americans in order to ensure they do not pay a lower rate than middle-class filers. Obama has used the measure as a political cudgel to assault Mitt Romney, who has dismissed the proposal as a campaign gimmick. The Buffett Rule is named after billionaire financier Warren Buffett, who has said that he pays a lower effective tax rate than his secretary. Legislation to enact it faces a vote in the Democratic-held Senate on Monday. It is expected to fail, but even if it succeeds it is sure to die in the Republican-led House of Representatives.

Yahoo News earlier Friday turned to the Obama campaign's Buffett Rule calculator to conduct a little experiment. The calculator is an oversimplified tool, but it reported that married filers with Breckenridge's income would typically pay an effective rate of 20.9 percent (a hair above Obama's 20.5 percent), while filers married with children would pay 17.6 percent (somewhat less than the married-with-children president). While we know Breckenridge is married, without data like her husband's income, the calculator's information is chiefly for entertainment purposes.

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Putting the Obamas' information into the calculator generates the message "Tax rates at the salary you entered vary significantly based on the level and nature of investment income, as well as other factors."

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