(Reuters) - Presidential hopeful Newt Gingrich's tax return, dramatically released on Thursday during a candidates debate, shows that his wealth comes from a media and consulting empire he built after leaving government, but yields more questions than answers about how he earns his money.
Gingrich's 2010 income was about $3.1 million. It came mostly from Gingrich Holdings, an umbrella company for a collection of lucrative enterprises. These included a company that produced films and books and one that consulted for health care companies.
Gingrich Holdings was dissolved last year in an overhaul of his conglomerate shortly before Gingrich jumped into the race for the Republican nomination to take on Democratic President Barack Obama in November.
The former speaker of the House of Representatives has hounded rival Mitt Romney over his tax returns. Romney initially waffled, then said he would release his returns in April, when the nomination may already be decided.
Gingrich's release of one year's tax return, while less forthcoming than the multiple-year tax forms released by some candidates in past campaigns, is sure to win him political points given Romney's stance. But the document itself is not especially illuminating.
"We can't see behind Gingrich Holdings or Gingrich Productions to see where that money is coming from," said Daniel Berman, a tax professor for Boston University who worked in Washington for decades.
A spokesman for Gingrich did not return requests for comment.
In a bit of backstage political theater, Gingrich issued his 2010 return during a Republican debate in South Carolina two days before the state's primary. Gingrich's pounding on the issue may be fueling his boost in polls before the vote there.
A new Reuters/Ipsos polls shows Gingrich closing the gap with Romney, who is still the presumed front-runner for the nomination, in the all-important southern state.
Gingrich reported in the 2010 joint return with wife Callista paying about $995,000 in federal taxes. On $3.1 million in income, that is a tax rate of more than 31 percent, double the rate Romney is likely to report when he reveals his filing.
Of the $3.1 million, about $450,000 was classified as "wages and salary"; $2.5 million was a lump sum related to Gingrich Holdings.
An earlier disclosure called most of that payment a distributive share from Gingrich Productions. The tax filing listed Gingrich as "consultant" and Callista as "executive."
The combined entity lists primary locations in both Washington, D.C., and Georgia, Gingrich's home state.
The return showed relatively scant income from capital gains and dividends, which are taxed at the 15 percent rate that Romney has said he pays.
Gingrich "has a normal spread of stock transactions and interest and dividends," said accounting professor Patrick Colabella of St. John's University. "What is missing out of this is Gingrich Holdings. That should be part of it."
For example, Gingrich has said that when he was in business, one of his clients was Freddie Mac. Since working for the mortgage finance giant, he has blamed it for contributing to the 2008 financial meltdown. The tax filing does not include details of this sort, shedding no light on Gingrich's client list.
Gingrich was heavily involved with the for-profit Center for Health Transformation, a consulting company that collected tens of millions of dollars in dues from health care companies.
Callista Gingrich took a leading role in Gingrich Productions, which created books and DVDs popular with conservative groups.
Because the groups are privately held, however, there is little known about their profits and revenues.
An ethics watchdog group is calling for a federal probe into Gingrich's work at the Center for Health Transformation for violations of a federal lobbying act, saying Gingrich worked for drug and other health care companies lobbying for passage of legislation adding a prescription drug benefit to Medicare.
Gingrich has said he had not technically "lobbied" at the group, though in Washington there is a gray area where former lawmakers and others can help companies but not technically be registered as a lobbyist.
Gingrich also earned a $76,200 annual pension from his days in Congress and paid nearly $20,000 in alimony. Callista is Gingrich's third wife, and an interview by second wife Marianne caused on a stir on Thursday after she told a reporter that Newt had asked for an "open" marriage.
Romney's inconsistency on the tax return issue lets Gingrich take the high road and avoid scrutiny.
"Releasing the tax return rarely helps a candidate, but it sure can hurt one who doesn't. That candidate looks like he has something to hide," said David Yepsen, director of the Paul Simon Public Policy Institute at Southern Illinois University.
"So far, no one has focused on what's in Newt Gingrich's return. The story has been Romney's release of his."
The debate moderator on Thursday asked Romney if he would follow the example of his father, former Michigan Governor George Romney, who released 12 years of tax returns when he campaigned for president in 1968.
"Maybe," Romney said, eliciting boos from the rowdy crowd.
Romney has been estimated to have a net worth of up to $270 million, much due to past investments from his time at Bain Capital. The former Massachusetts governor made his fortune as a manager for Bain, a private equity firm where managers often pay the lower 15 percent capital gains rate on much of their income.
Reporting by Kim Dixon in Washington and Marcus Stern in Atlanta; Editing by Kevin Drawbaugh and Doina Chiacu