1) The Tax Policy Center bent over backwards to make Romney’s promises add up. They assumed a Romney administration wouldn’t cut a dollar of tax preferences for anyone making less than $200,000 until they had cut every dollar of tax preferences for everyone making over $200,000. They left all preferences for savings and investment untouched, as Romney has promised. They even tested the plan under a model developed, in part, by Greg Mankiw, one of Romney’s economic advisers, that promises “implausibly large growth effects” from tax cuts. The fact that they couldn’t make Romney’s numbers work even when they stacked all these scenarios on top of one another shows just how impossible Romney’s promises are.
2) The reason Romney’s plan doesn’t work is very simple. The size of the tax cut he’s proposing for the rich is larger than all of the tax expenditures that go to the rich put together. As such, it is mathematically impossible for him to keep his promise to make sure the top one percent keeps paying the same or more.
3) This is going to be a huge problem for the Romney campaign. The Romney team has tried to paper over the fact that its policy promises don’t add up by withholding the crucial details that independent analysts need to do the math. But now independent analysts are filling in those details for them (the Tax Policy Center’s look at Romney’s tax plan should be read in tandem with the Center on Budget and Policy Priorities effort to flesh out his spending promises). And, ultimately, that’s worse, as actors with more credibility than the Romney campaign are showing what the Romney campaign was trying to hide.
4) Evidence the Romney campaign does not have a good counterargument, part one: If they thought releasing more details would make the plan look better rather than worse, they would have released them rather than letting outside organizations fill in the blanks. It’s essentially the same theory as refusing to release the tax returns. But now the Romney campaign is receiving pressure — including from conservatives — to release those details, which they know they can’t do. And unlike on the tax returns, no one can say that the details of Romney’s plans for governing the country are irrelevant to this campaign.