"The FairTax will not be revenue neutral (i.e. bring in the same revenue as the current system) at 23%"
The truth: The FairTax rate of 23% (when calculated inclusively like income tax rates) has been thoroughly researched to provide all the revenues now collected under both the income tax system and through FICA payroll taxes. Reports otherwise are largely based on the President's Advisory Panel on Tax Reform which declared the rate would have to be much higher. What the Panel failed to make clear in an amazingly shameless sleight-of-hand is that they never studied the FairTax legislation as it exists in pending legislation. They ignored $22 million of FairTax research and, instead, quietly devised their own national consumption tax which they loaded with the exemptions and deductions they felt were "politically realistic". They also failed to calculate the effects of elimination of the FICA tax on annual taxpayer burdens or on the distributional effects of the FairTax across the income spectrum. Upon completion--and after declaring a national consumption tax flawed--they then refused to publish their underlying assumptions.
For more information on this topic, see these research papers.