Yes, of course Congress can raise the FairTax rate just as it could raise the flat tax rate or can and does raise the income tax rate. And if we in the grassroots allow them to do it, shame on us!

However, the FairTax is highly visible. And because there is only one tax rate, it will be very hard for Congress to adopt the typical divide-and-conquer, hide-and-disguise, strategy employed today to ratchet up the burden gradually, by manipulating the income tax code. Ultimately, the tax rate will be dictated by the size of government. If government gets larger, higher tax rates will be required. If government shrinks relative to the economy, then the tax rate will fall. Federalist 21, by Alexander Hamilton, is a great read on the futility of government raising a consumption tax too high, and thus reducing revenues.