Add in a prebate that pays you a monthly amount equal to the amount typical for necessities, (see www.fairtax.org/PDF/2009FairTaxPrebateSchedule.pdf
), and you have a very fair system. Plus you get to eliminate the IRS and the ever hanging threat of some future president using the threat of audit for political gain.....Oh wait that's happening now.
A national sales tax is a good idea. In the current system, some states have intentionally low taxes in order to attract businesses and consumers, which can lead to capital flight from other states. Also, is it truly just to have consumers in New York, who use New York government services, buy all their things more cheaply in New Jersey? Consumers should pay where they live, and in a nation with many states, only a national sales tax will truly accomplish this goal, preventing distortion of consumer behavior.
From my understanding, the concept of a national sales tax is to get rid of federal taxes and replace them with a sales tax of 15% flat. Personally, I would find this to be a difficult thing to accommodate in addition to the already high state sales tax in my state, and I'm sure many other Americans would agree. It's difficult enough for people to figure out a 15% tip, so figuring out how much tax they'll have to pay on all purchased would be challenging. It also seems like an unfair burden on young people, such as children who get allowances, who aren't yet at the point where they currently pay federal taxes.