Mitt's tax bombshell?

I saw an article that speculates that what Mitt is hiding in his tax returns:
It is an amnesty that the IRS offered on Swiss Bank accounts in 2009.

Here’s an excerpt:

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.

So, Mittens the tax evader took advantage of the IRS amnesty program?
I wonder how many years he was cheating on his taxes?