[cercis]

The major negative is that no one can agree about the amount that should be exempted.

Most people agree that some should be exempted, but no one agrees what it should be.

The thought on the exemption is that it takes a certain amount to live, poverty level as it were. Now, most of us know the poverty level is pretty much a joke in that no family could actually live on poverty level wages (unless they are getting major welfare, etc). The thought is that you should be taxed on your "disposable income". Well, then you have the people who claim that as your income increases your expenses must also increase (I guess they think they HAVE to have that 5 bedroom mcmansion and the lexus).

The positive is that it is easier to figure out. You state your income, deduct the living expense allotment and then multiply by the percentage.

Another negative is that no one is sure what the percentage should be. And a lot of charities are afraid (probably rightfully so) that they will see a major decrease in contributions when the tax deduction incentive is removed.

There's also the negative of what constitutes income. Does interest earned on inherited investments count as income? If not, then you can have someone who has never worked a day in their life but who collects in excess of $100k/year and not owe anything in taxes.