When attempting to engage in baseless speculation over what it is that's in Mitt Romney's tax statements that's so embarassing he'd rather take the heat for non-disclosure, I think it's important to remember that he was actively running for president in 2007 and 2008. That means it's relatively unlike he was doing anything during those years that he thought couldn't withstand scrutiny. So why not release a nice even five years of tax data? Perhaps because of something that happened in 2009.
Wealthy U.S. taxpayers, concerned about an Internal Revenue Service crackdown on the use of secret overseas bank accounts as tax havens, are rushing to meet a Thursday deadline to disclose those accounts or face possible criminal prosecution. The concern was triggered this summer when Switzerland's largest bank, caught up in an international tax evasion dispute, said it would disclose the names of more than 4,000 of its U.S. account holders.
The decision shattered a long-held belief that Swiss banks would guard the identities of its American customers as carefully as they did their money, and it raised concern that other international tax havens might be next. Under an amnesty program, the IRS is allowing taxpayers to avoid prosecution for having failed to report their overseas accounts. As a result, tax attorneys across the nation have been besieged by wealthy clients who are lining up to apply even though they will still face big financial penalties.
Romney might well have thought in 2007 and 2008 that there was nothing to fear about a non-disclosed offshore account he'd set up years earlier precisely because it wasn't disclosed. But then came the settlement and the rush of non-disclosers to apply for the amnesty. Failing to apply for the amnesty and then getting charged by the IRS would have been both financially and politically disastrous. So amnesty it was. But even though the amnesty would eliminate any legal or financial liability for past acts, it would hardly eliminate political liability.