Eliminating the biggest deductions and exclusions is extremely unlikely, and flatter rates alone won't make the tax system any simpler. It would, however, make it far less progressive. Next year must be divisible by four because the flat tax, one of the hardy perennials of bad tax policy, has come bouncing back like a bad penny. The flat tax is typically marketed as a way to achieve drastic tax simplification—something virtually everyone favors, at least