http://www.factcheck.org/elections-2008/the_whoppers_of_2007.html"FairTax" Falsehoods
Proponents of the so-called "FairTax," prominently including Huckabee, claimed that a national sales tax of 23 percent could replace both the federal income tax and Social Security taxes, and eliminate the Internal Revenue Service.
In truth, the actual rate of the proposed tax would be 30 percent, when calculated the same way as state and local sales taxes. And it would have to be 34 percent to raise the same revenue as the taxes it would replace, according to a bipartisan presidential commission. The FairTax would, for example, raise the price of gasoline by roughly $1 per gallon at today's prices and cause a $150,000 new home to cost at least $195,000 including the 30 percent tax.
And while the Internal Revenue Service might disappear, two new federal bureaucracies would be needed: one to administer the sales tax and another to keep track of sending out hundreds of billions of dollars in checks every year to compensate taxpayers for the regressive nature of sales taxes. The proposal calls for "prebates" to all taxpayers of all taxes paid on purchases up to the poverty level. That of course would require an IRS-like system to validate each person's income and the amount of "prebate" they are due.
Unspinning the FairTax May 31, 2007The article on the Fair Tax is a little more than 1/2 way down the page.
Here is a link to how they made their determination.
http://www.factcheck.org/taxes/unspinning_the_fairtax.html