His 2010 returns showed that Romney took in $21.7 million in income in 2010 and paid $3 million in taxes, or a little less than 14 percent.
The returns also showed that Romney gave $3 million in charitable donations in 2010, including $1.5 million to the Mormon Church.
As calls intensified for Romney to release as many as 10 years of returns, the candidate continued to point to Sen. John McCain, R-Ariz., the 2008 Republican presidential nominee, as his role model on the issue. Romney noted that McCain only released two years of tax returns and maintained that he, Romney, had done everything "required of him by law" when it came to his financial documents.
But the criticism only continued when it emerged that Romney's campaign had requested "several years" of tax returns from those who were vetted as potential vice presidential candidates.
The focus on Romney's tax returns has long irritated Romney advisers, who believed the issue took Romney off message and dominated the news cycle when they would rather have focused on the economy.
For example, during a news conference in August that was intended to focus on his Medicare plan, Romney was hounded about his taxes and asked whether he'd kept a promise he made to ABC News, during an interview in Jerusalem, to "go back and look" and see if he'd ever paid a tax rate lower than 13 percent.
"I did go back and look at my taxes, and over the past 10 years I never paid less than 13 percent," Romney said at the time.
So why did Romney wait so long -- with Election Day so close -- to release his returns? The candidate and his wife told Parade magazine in August that one of the reasons they had hesitated to release their financial documents was the amount of money they give the Mormon Church.
"Our church doesn't publish how much is given," Romney told the magazine. "One of the downsides of releasing one's financial information is that this is now all public, but we had never intended our contributions to be known. It's a very personal thing between ourselves and our commitment to our God and to our church."
Lauren Pearle contributed to this report