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President Obama's campaign continues to hammer Mitt Romney over the GOP challenger's refusal to release more of his tax returns. Governor Romney has provided records from one year, and he's promised a second. Even some powerful Republicans voices are now saying that's not enough. Plus, what he has released is raising new questions.
NPR's Scott Horsley has the latest.
SCOTT HORSLEY, BYLINE: President Obama's campaign launched a new TV ad this week, shining a spotlight on what we do and don't know about Mitt Romney's taxes.
(SOUNDBITE OF POLITICAL ADVERTISEMENT)
UNIDENTIFIED MAN: Tax havens, offshore accounts, carried interest. Mitt Romney has used every trick in the book. What is Mitt Romney hiding?
HORSLEY: So far, Romney and his family trust have released their 2010 tax returns, which fill hundreds of pages. He got an extension for his 2011 return, and has promised to release that as soon as it's ready - no later than mid-October. Romney told CNN last week that should be enough.
(SOUNDBITE OF CNN BROADCAST)
MITT ROMNEY: Those are the two years that people are going to have. And that's all that's necessary for people to understand something about my finances.
HORSLEY: But tax professionals still have plenty of questions. For example, Lee Sheppard, who's a contributing editor at the journal Tax Notes, wants to know how Romney amassed so much money in his tax-deferred retirement account.
LEE SHEPPARD: All we know is that it's a big number, and we're a little bit baffled as to how it got so big.
HORSLEY: Romney's retirement account is worth somewhere between 21 million and $102 million.
Law professor Ed Kleinbard of USC says that's a lot of money, considering the most Romney could ever contribute to the account was $30,000 a year.
ED KLEINBARD: Either Governor Romney is sort of the modern-day equivalent of Jack and his magic beans, who somehow created a mighty beanstalk, or he took very aggressive positions with respect to valuing insider stock.
HORSLEY: Kleinbard means Romney might have loaded up his retirement account with assets from his private equity firm, Bain Capital, and assigned artificially low values to those assets in order to get around the contribution limits.
If so, Romney would still have to pay taxes on the real value of the assets, when they're withdrawn from the account. But in the meantime, the money can grow, tax-free. Tax Notes' Sheppard says that's an advantage most taxpayers don't have.
SHEPPARD: If you happen to work for a partnership and your compensation is arranged this way, you get this very beneficial treatment.
HORSLEY: Romney's campaign did not respond to NPR's questions about his retirement account. But his taxes have been dogging the candidate since the GOP primary. At an NBC debate in January, Romney argued there's nothing wrong with minimizing taxes.
(SOUNDBITE OF NBC DEBATE)
ROMNEY: 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.
HORSLEY: Romney was equally aggressive towards taxes in the business world. For years, he was the director of Marriott International, the hotel company founded by his namesake, Willard Marriott. Kleinbard, who worked on Wall Street and served as chief of staff for Congress' Joint Committee on Taxation, says Marriott had a reputation.
KLEINBARD: Marriott was always a tax shelter promoter's first call. Marriott was one of those companies that just loved to buy tax shelters.
HORSLEY: Bloomberg reported this year on one Marriott tax shelter known as Son of BOSS. It involved creating paper losses to offset taxes on real income. The IRS challenged the shelter, and Marriott lost in court. The company was forced to pay $29 million. Kleinbard notes when the shelter was adopted, Romney was the chair of Marriott's audit committee.
KLEINBARD: It's the job of the chair of the audit committee of Marriott to say, wait a minute, just because we have an opinion from Winkin', Blinkin', and Nod saying that this is a terribly clever idea, I need to apply some common sense.
HORSLEY: A statement from Marriott says the company only engages in tax deals it believes are lawful.
Kleinbard sees a pattern for Romney of cutting tax corners. Asked about his taxes in that NBC debate, Romney sidestepped.
(SOUNDBITE OF NBC DEBATE)
ROMNEY: The real question is not so much my taxes, but the taxes of the American people.
HORSLEY: Romney, whose 2010 tax rate was less than 14 percent, says he wants to overhaul the tax code, which he calls far too complex, far too intrusive and far too great.
Scott Horsley, NPR News, Washington.