Other than the fact that it's horribly regressive and won't do what it's proponents say it will? Absolutely nothing....;-D... http://www.factcheck.org/taxes/unspinning_the_fairtax.html http://www.brookings.edu/views/articles/gale/20050516.pdf Or, if you don't want to read that monster PDF in the second link, here's the relevant conclusion:" "...it is not possible to do all of the following three things at the same time: (a) repeal the existing income, corporate, payroll, and estate and gift taxes, (b) impose a 23 percent tax-inclusive (30 percent tax-exclusive) national retail sales tax, and (c) maintain the real levels of government revenues and the real size of government spending programs. Even if there were no avoidance, no evasion, no legislative erosion of the private consumption tax base, and no effort to spare state and local governments, the required revenue neutral rates would be 31 percent on a tax-inclusive basis and 44 percent on a tax-exclusive basis. Alternatively, if the tax rate were kept at 23 percent (tax-inclusive), the revenue loss would exceed $7 trillion over the next decade relative to current law..."

It makes too much sense and would take away most of the power and control beauracrats have over the people. It's a great idea but it will unlikely never be adopted for this reason. Government officials love power, and will not allow it to be taken away, even if it is for the good of the people.