Mitt Romney once again tried to put the issue of his tax history to bed today by announcing that he has paid at least a 13% tax rate every year for the past decade. This claim is meaningless, because he doesn't make clear what it is that he's paid 13% of. If he's referring to his adjusted gross income, or his income that's not in a foreign account, then the 13% number is not what really matters. If, for example, he made $10 million but only $1 million was reported as taxable income, he could claim that he paid a 13% rate but it was actually only 1.3%. He might have accomplished such a deception by keeping money overseas, or stashing it in his huge IRA, or other accounting tricks like carried losses.
Without more specifics, Romney's statement today is meaningless, and hopefully he isn't allowed to wriggle off the hook so easily.