Mitt Romney’s tax returns shed some light on his investment wealth.

Mitt Romney offered a partial snapshot of his vast personal fortune late Monday, disclosing income of $21.7 million in 2010 and $20.9 million last year — virtually all of it profits, dividends or interest from investments.

None came from wages, the primary source of income for most Americans. Instead,Romney and his wife, Ann, collected millions in capital gains from a profusion of investments, as well as stock dividends and interest payments.

The couple gave away $7 million in charitable contributions over the past two years, including at least $4.1 million to the Church of Jesus Christ of Latter-day Saints. Romney’s family has for generations been among the Mormon Church’s most prominent members.

The Romneys sent somewhat less to Washington over that period, paying an estimated $6.2 million in federal income taxes. According to his 2010 return, Romney paid about $3 million to the IRS, for an effective tax rate of 13.9 percent.

For 2011, Romney estimates that he will pay about $3.2 million, for an effective rate of 15.4 percent. That’s in line with his earlier estimates, but sharply lower than the rates paid by President Obama and Romney’s closest Republican rival, Newt Gingrich.

“You’ll see my income, how much taxes I’ve paid, how much I’ve paid to charity,” Romney said at a debate Monday night in Tampa. “I pay all the taxes that are legally required and not a dollar more. I don’t think you want someone as the candidate for president who pays more taxes than he owes.”

He said his tax bill is “entirely legal and fair,” adding: “I’m proud of the fact that I pay a lot of taxes.”

Romney released his tax returns — nearly 550 pages, including the 2010 returns for three family trust funds and a foundation — in a bid to regain his footing in the Republican presidential campaign after stumbling badly in last weekend’s South Carolina primary.

The Romney campaign planned to publicly release the tax documents Tuesday morning but gave a preview late Monday night to The Washington Post.

In recent days, Romney’s GOP rivals have pressed him to make his returns public, arguing that it is critical for the public to vet his finances before the party settles on its nominee. The revelation that Romney pays a significantly lower tax rate than most wealthy Americans underscores his image as a multimillionaire financier, an image that some Republicans believe would hurt his chances in the general election.

Economic inequality is emerging as a central theme in the battle for the White House, with Obama trying to harness populist anger at Wall Street and corporations against a backdrop of chronically high unemployment. He plans to call for higher taxes on millionaires in his State of the Union address to Congress on Tuesday night, embracing an idea advanced by billionaire investor Warren Buffett and Occupy Wall Street protesters.

“The president believes that it is not fair — inherently not fair — that those who are millionaires and billionaires pay at a lower rate than average Americans who are struggling to get by,” White House press secretary Jay Carney told reporters Monday. “This theme about economic insecurity for the middle class . . . is what got this president into politics. So this is a foundational belief for him, and he’s happy to have that debate.”