After being soundly beaten by former House Speaker Newt Gingrich in South Carolina's Republican presidential primary, former Massachusetts Gov. Mitt Romney is pledging to release tax returns for at least one year.

On Sunday, Romney admitted to Fox News host Chris Wallace that he had made a "mistake" by not releasing his tax information earlier.

"What we said was I was planning on releasing them in April when they had been released by other candidates in the past," Romney said. "But you know what? Given all the attention that's been focused on tax returns, given the distraction that I think they became in these last couple of weeks, look, I'm going to make it clear to you right now, Chris, I will release my tax returns for 2010, which is the last returns that were completed."

"I'll do that on Tuesday of this week," he added. "I'll also release at the same time an estimate for 2011 tax returns. So you'll have two years. People can take a good look at it. We'll put them on the website and you can go through the pages. This, I think, we just made a mistake in holding off as long as we did."

Wallace noted that Romney's dad, George Romney, had released 12 years of tax returns during his 1968 bid for president.

"Well, that will be more than any other Republican candidate," Romney said of his pending release. "I'm not going to go back to my dad's years. That was even before the Internet. We'll be putting our returns on the Internet. People can look through them."

"Are there more political problems in these tax returns?" Wallace wondered. "Like the 15 percent [effective tax rate], like the investments in offshore accounts in the Cayman Islands?"

"I'm sure the Democrats will do there very best to see if they can't find something that stirs up political interest," the candidate agreed. "But, look, the income I have is derived from the interest described in the financial disclosure report. The Cayman Islands account, so to speak, is apparently an investment that was made in an entity that invests in the United States. The taxes paid on that are full U.S. taxes. ... We pay full fair taxes, and you will see it's a pretty substantial amount."

Watch this video from Fox News' Fox News Sunday, broadcast Jan. 22, 2012.