Mitt and Ann Romney paid an average effective federal tax rate of 20.2% and owed both state and federal income taxes every year over the 20-year period ending in 2009, the GOP presidential nominee’s campaign said on Friday in response to nagging questions about his tax returns.

The Romney campaign said in a blog post that it will release at 3 p.m. ET Romney’s 2011 tax return with the Internal Revenue Service as well as a notarized letter from PricewaterhouseCoopers giving a summary of the Romneys’ tax returns from 1990 to 2009.

Brad Malt, the trustee of the Romneys’ blind trust, said in the post that the Romneys’ lowest annual effective federal personal tax rate was 13.66% over the 20-year period. The couple gave to charity an average of 13.45% of their adjusted gross income.

The total federal and state taxes owed plus the total charitable donations deducted represented 38.49% of total adjusted gross income.

Malt also said Mitt and Ann Romney paid 100% of the taxes they owed during the 20-year period covered by the PWC letter.

The disclosure comes after the Romneys filed their 2011 tax return with the IRS on Friday morning.

The couple paid $1,935,708 in taxes on $13,696,951 in income, which was “mostly” investment income. Their effective tax rate for last year was 14.1% and they donated $4,020,772 to charity, amounting to almost 30% of their income.

Malt said the Romneys claimed a deduction of $2.25 million of those charitable contributions.

Malt also said that while the 2011 charitable donations would have “significantly reduced” the amount of taxes they owed for the year, the Romneys decided to limit their deduction of charitable contribution to conform to Romney’s August statement that based upon the January estimate of income they paid at least 13% in income taxes in each of the last 10 years.

By comparison, President Obama said he and Michelle Obama earned $789,684 in income in 2011 and paid a 20.5% tax rate, while giving 22% to charity.

U.S. taxpayers paid an average rate of 11.8% in 2011, while the average rate for Americans making over $1 million is 23%, according to the IRS.

The Romney campaign released the 2011 tax return and post the PWC letter at www.mittromney.com/disclosure.

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