CHARLESTON, South Carolina (Reuters) - Republican presidential hopeful Newt Gingrich released his tax returns on Thursday, revealing that he and his wife Callista paid $995,000 on an income of $3.1 million in 2010.
In a move designed to embarrass rival Mitt Romney, who has not made his tax forms public, Gingrich issued his returns during a presidential debate in South Carolina.
The bulk of Gingrich's income appears to come from Gingrich Holdings, one of the companies run by Gingrich before he ran for president. Of his total income, $2.4 million, apparently largely related to Gingrich Holdings, was likely taxed at the "ordinary income" tax rate of 35 percent.
Gingrich's return showed relatively small capital gains and dividends holdings, which would be taxed at the 15 percent rate - about what Romney estimated his effective tax rate would be earlier this week.
Altogether, Gingrich paid a tax rate of 31.5 percent in 2010. The campaign said Gingrich and his wife donated $81,000 to charities in 2010.
During Thursday's debate, Gingrich called on Romney to release his tax returns now while the presidential race was still reasonably early.
"If there's anything in there that is going to help us lose the election, we should know before the nomination. If there's nothing in there, why not release it?" Gingrich said.
"I'll release my returns in April, and probably for other years as well," Romney, a multimillionaire, said.
The debate moderator asked Romney if he would follow the example of his father George, who released 12 years of tax returns when he campaigned for president in 1968.
"Maybe," Romney said.
This week, Romney said that he pays a tax rate close to 15 percent, much lower than that of most working Americans, because much of his earnings come from investments.
"I'm not going to apologize for being successful," Romney said.
Rick Santorum, a former U.S. senator from Pennsylvania who is battling with Gingrich to be the conservative alternative to Romney, said he would release his tax returns, but they were at home on his computer.
Speaking before Gingrich released his returns, New York high net worth attorney Asher Rubinstein said Romney's 15 percent tax rate was legal and to be expected.
"Newt Gingrich has stated that his tax rate was 31%, in contrast to Romney's 15 percent. It seems ... that Mr. Romney is not only a better investor, he also consulted better tax lawyers," he said.
(Reporting By Samuel P. Jacobs; Reporting by Kim Dixon; Editing by Eric Walsh and Philip Barbara)