For starters, I have done a subject just like this
Link had my butt wiped across the floor because of a previous subject I did on welfare.
As for a national sales tax. NO WAY. The main reason being that it would be abused to no end. The poor with medical problems would pay way more than a healthy wealthy person. It especially wouldn't work because people have a tendency to spend more than they make hence paying more in taxes than they can actually afford.
Flat tax IS the way to go. No loopholes, no credits for nothing. you make $10,000 a year, you pay the same percentage as the guy making $1,000,000 a year. There is nothing unfair about it. It would also act as an incentive or sorts to make more since you know what you will pay in taxes will never be disproportionate to what you make. I see no reason why we should punish the rich and reward the poor. That's just ludicrous.
"Well deary, you have 3 kids and make around $15,000 a year at Burger Shot? We'll give you $8,000 more in February just because we can, and that won't count against your food stamps, TANF, medical, subsidized housing, or any of your other assistance. But if you make much more than that, we are not going to give you that extra money for being poor."
Then the rich/middle class gets punished for working hard and "getting ahead" "Well, you have worked hard and got an education and put jobs, products and services into our economy so now we will punish you with a 40% tax liability, better get a good Accountant (whom you will pay also) to help you find loopholes"
That sound real fair to me. *dripping sarcasm*