US Constitution Article I Section 9 - Limits to Legislation
No capitation, or other direct, tax shall be laid, unless in proportion to the census or enumeration herein before directed to be taken.

16^th Amendment (1913)
The Congress shall have power to lay and collect taxes on incomes, from whatever source derived, without apportionment among the several States, and without regard to any census or enumeration.

What is the FairTax plan?
The FairTax plan is a comprehensive proposal that replaces all federal income and payroll taxes with an integrated approach including a progressive national retail sales tax, a rebate to ensure no American pays federal taxes up to the poverty level, dollar-for-dollar revenue neutrality, and the repeal of the 16^th Amendment. This non-partisan legislation (HR 25/S 25) abolishes all federal personal, gift, estate, capital gains, alternative minimum, Social Security, Medicare, self-employment, and corporate taxes and replaces them all with one simple, visible, federal retail sales tax – collected by existing state sales tax authorities. The FairTax taxes us only on what we choose to spend, not on what we earn. It does not raise any more or less revenue; it is designed to be revenue neutral. So it is also cost neutral – the final cost for goods and services changes little under the FairTax. The FairTax is a fair, efficient, transparent, and intelligent solution to the frustration and inequity of our current tax system.

Thoughts about the Fair Tax
401K and IRA holders will benefit as the income from those earnings will be taxed only once under the new NST (National Sales Tax). Holders of post tax savings will get to pay tax twice on their dollars. That's not fair.

Will renters have to pay sales tax on rents and leases?

Tax on services includes professionals like doctors, lawyers, accountants and computer programmers. The theory is that the total price paid will stay the same because the professionals will be able to reduce their rates because they won't have to pay payroll and income taxes.

Buy a new car and pay 30% sales tax,  buy a used car from the same dealer and pay none. Will the dealers sell all cars as "Used?" and charge a premium for the privilege of buying "Used?"  A demo with a couple of thousand miles on it could be tax exempt. Buy a new car and pay $20,000 plus $8,000 sales tax  (30%NST plus 10% state and local ST). Buy the same car with 5,000 miles of demo use and pay $22,000 plus $2,200 state and local tax.

Will most CPAs go out of business?

Will new methods for tax evasion surface and threaten the mainstream? Will undocumented, underground barter and cash economies continue to thrive?