Mitt Romney is adamant about not releasing any of his tax returns from before 2010, and he's getting hammered for it politically. "The costs of not releasing the returns are clear," conservative columnist George Will told ABC News. "Therefore, he must have calculated that there are higher costs in releasing them." What could be so bad? There are lots of theories, but reporters and commentators are zeroing in on 2009 as the speculative problem year, since Romney has released or promised to release (most of) his 2010 and 2011 tax documents and handed over more than 20 years of returns in 2008 to Sen. John McCain's vice-presidential vetters — and McCain says there was nothing disqualifying in them. One theory gaining traction is that Romney paid zero taxes in 2009. The Romney campaign says that's "not true." But is it actually possible?

The zero-tax theory makes the most sense: Romney, like his peers among the ultra-rich, probably lost a bundle in the 2008 market collapse, says Joshua Green at Bloomberg Businessweek. "It's possible he suffered a large enough capital loss that, carried forward and coupled with his various offshore tax havens, he wound up paying no U.S. federal taxes at all in 2009." That is "unfounded, though not implausible, speculation," of course, but paying zero taxes would be "politically deadly" enough to justify the heat he's taking for keeping pre-2010 returns private.
"What's Romney hiding in his tax returns?"

Romney almost certainly paid some taxes: Based on Romney's 2010 returns, "we know he had no taxable capital gains in 2009," says Josh Barro at Bloomberg View. "But big capital losses alone wouldn't be enough to save Romney from paying any tax." He couldn't offset his millions in other income with capital losses, and doesn't appear to have taken other common strategies to bring his 2009 tax bill to $0. My bet is that he just used "aggressive tax planning strategies that are legally, but not politically, defensible."
"New thoughts about what's hiding in Romney's tax returns"

Low taxes would be bad enough: I agree that Romney probably "paid some federal taxes in 2009," says Ezra Klein at The Washington Post. For one thing, "the sort of tax sheltering he would have needed to get to zero would be quasi-suicidal for a presidential aspirant." But he could have gotten his effective tax rate down to "3 or 4 or 5 percent," and that would be "nearly as bad as zero." Why would a presidential wannabe do that? It's normal for Romney's income bracket, and "people running for office are human beings who procrastinate and make bad decisions and get distracted," too.
"Did Mitt Romney pay any federal taxes at all in 2009?"

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