Girl in the OC,
The AMT is the alternative minimum tax. It was created (from fuzzy memory) in the 70s. It is an entire system of income taxation that rides paralell to what we normally think of. It was designed to tax a small group of people - like 2000 in the 70s based on their gross income. The number (again from fuzzy memory) is something like 270K/ year. (Would have been nice to make that in the 70s, huh? =). Well, that number never adjusted for inflation and more and more couples are running up against it. One of the major differences is the deductions that can be taken - for AMT, they are rare.
The HMID - housing mortgage interest deduction - allows homeowners to stash away money in their home for retirement and deduct up to 500K (with provisions) once they sell.
For some perpsective, in 2002 (might have been 03, but the idea is the same), the Fed government had the authority to tax 1.6 Trillion dollars, instead 900 billion was deducted and 700 billion was recieved.
How and why does all this happen? The tax code is political. Rather than tax to raise money for the necessary things, deals and work-arounds in the tax code are created to attempt to achieve the same thing.
I say keep the AMT, let all the politicians sit on their hands and have it slowly produce income for the U.S. govt to pay off it's interest payments. Win-win for D.C. , none of the politicians is bad guys and the debts get paid down. Of course, that's just wishful thinking, they'll get more money and blow it on fast cars and booze - idiots.