That's slightly above the 13.9 percent rate the couple paid in 2010. Most of the 2011 income was from investments.
On average, middle-income families making from $50,000 to $75,000 a year, pay 12.8 percent of their income in federal taxes, according to Congress' Joint Committee on Taxation.
Campaign officials said the couple filed the return Friday with the Internal Revenue Service, after receiving an extension. They were to publicly release their full 2011 returns late Friday.
Romney's taxes have emerged as a key issue during the 2012 presidential race with President Barack Obama. Romney released his 2010 tax returns and a 2011 estimate in January, but he has declined to disclose his returns from earlier years.
His vast fortune and his long association with Bain Capital, the private equity firm he cofounded, have been much discussed this year.
Romney paid about $3 million in federal income taxes in 2010 — an effective rate of 13.9 percent.
Critics, including Obama, have urged Romney to release more than just the two years of returns and follow his father's model. When George Romney ran for president, he released 12 years of tax returns.
Mitt Romney's campaign did put out a summary Friday by Brad Malt, the trustee of the couple's blind trust, saying that over the 20-year period between 1990-2009, the Romneys owed both state and federal income taxes and paid federal taxes at an effective annual rate of 20.2 percent
Obama's own tax return for last year showed that he and his wife, Michelle, paid $162,074 in federal taxes on $789,674 in adjusted gross income, an effective tax rate of 20.5 percent. Their income plunged from $1.7 million in 2010, with declining sales of the president's books. In 2009, the Obamas reported income of $5.5 million, fueled by the best-selling books.
The Romneys' exact totals for 2011 were federal taxes of $1,935,708 and on income of $13,696.951.
Most of Romney's income is from investments held in a blind trust, and campaign aides have stressed that he makes no decisions on how his money is invested.
During the 20-year period, the Romneys paid an effective federal income tax rate of between 13.45 percent and 13.66 percent each year, trustee Malt wrote.
For last year, the Romneys claimed a deduction for $2.25 million of their $4.021 million in charitable contributions, Malt said. In the previous year, a large percentage of those contributions went to the Mormon Church.
They could have claimed a higher charitable deduction, Malt said, but the couple "limited their deductions of charitable contributions to conform to the governor's statement in August, based on the January estimate of income, that he paid at least 13 percent in income taxes in each of the last 10 years."
Romney told reporters in August that he's never paid less than 13 percent of his income in taxes during the past decade. He said that Democratic Senate Majority Leader Harry Reid's claim to have heard that he paid no taxes in some years was "totally false."
