You mean where lines 28 - 33 of "Table two: National FairTax rate calculation, 2003" spell out the rates with rebate and then without rebate ?
19.3% of the Base Reduction Amount $1,746.1B (the poverty line spending that the FCA offsets) is $337B.
That doesn't seem very hidden to me.
http://www.fairtax.org/pdfs/Opportunties_tax_systems.pdf
Also noticed some glaring errors in Table 2 where they figured "Revenues to be Replaced". They had IRS 2004 numbers as:
Income....$927.7
Estate....$22.4
Payroll...$717.8
Total....$1,667.9 Billion
A quick visit to the IRS stats revealed several errors and omissions, like completely forgetting to add corporate taxes. Here are the IRS real numbers.
Income....$990.2
Corp......$230.6
Payroll...$717.2
Excise.....$24.1
Total.....$1962.1 Billion
The good ole Fairtax experts under calculated replacement taxes by $294 Billion, or about 18%. It is amazing how in 5 minutes time I can find such negligence in their calculations by their high paid experts.