Perry's tax plan is in many ways the usual nonsense, not really worth addressing seriously. For example, it's clearly a huge revenue-loser, is a huge tax break for the wealthy, etcetera.
This is all par for the course. But here are a few particular points about his plan's distinctive quirks that are worth emphasizing.
First, the idea of an election between the simple system and current law is simply nonsense. Goodbye simplicity. People with tax planning capacity are going to be running the numbers to see which is better. Does anything with the slightest bit of common sense really think a well-advised taxpayer going to opt for the postcard return even if, due to base-broadening, it turns out this would increase his or her tax liability by several thousand dollars a year? Adding elections adds complexity, it generally doesn't reduce it.
Second, why even bother having a flat tax if you are going to retain big itemized deductions, such as for home mortgage interest, charitable contributions, and (if I am reading the under-specific language correctly) state and local tax deductions?
Third, how can he purport to combine a flat tax (and simplification) with phasing out the itemized deductions for people who earn more than $500,000? True, this increases the progressivity of the plan, at least relative to providing the deductions and not phasing them out. But this effectively adds higher tax rates to people in the phase-out range, albeit eventually declining back to 20% once all the deductions are gone. And with this feature, that is going to be some postcard.
Fourth, can anyone seriously doubt that the exemption for dividends and capital gains will be exploited by tax planners, on behalf of owner-employees, to avoid paying even 20% on what is effectively wage income?
Fifth, how exactly is he going to broaden the base of the corporate tax to pay for lowering the corporate rate to 20%? Note that some of the key items often called corporate tax preferences disappear under a consumption tax - and at the individual level the so-called flat tax is in fact a consumption tax. Is he going to get rid of accelerated depreciation and LIFO accounting for inventory? Under a consumption tax, the purchase price of items such as equipment and inventory would be expensed. So, unless he wants to confine the shift from an income to a consumption tax to the individual level, and still inexplicably apply income tax-style accounting just to the corporate tax, I certainly don't see what sort of base-broadening he has in mind at the corporate level. To the contrary, it seems likely that he would want to make changes that would reduce corporate taxable income at the same time that he wants to lower the corporate rate.
So the Perry plan in many ways makes less sense than Cain's 9-9-9 plan.