The AMT is a tax for trying to get rich people writing off tons of income to pay a minimum amount on all of it.
A couple of HUGE problems come from this tax however...
The first example is soon to be a big problem for large and low-income families. An approximate example would be if a family of 7 or 8 that made $30,000 per year gets write-offs that bring their taxable income down to $15,000, and would normally pay the smallest tax percentage on that amount. The AMT comes into play here and says that the family must pay at least 26% on the $30,000.
My example of AMT abuse comes from being the first employee at .com e-tail pioneer Value America. I received A LOT of incentive stock options, and the company took off in 1998-9 like many .coms. The point at which I exercised (bought) 520,000 of my vested options, I paid $0.58 a share and the stock was worth about $15 per share ($74 a week later!!!) The "profit" ($15 - $0.58 = $14.42 per share) is not standard taxable income to the IRS, but it is subject to AMT. Therefore, since AMT tax at that level is 28%, I owed $2.1M in tax after taking out a LOAN for $250K to exercise shares. Value America then proceeded to tumble into oblivion. Through a combination of bad advice, and being too honest and ignorant to sell my shares when I had knowledge of negative insider information, I sold no shares. However, the IRS still says that I owe $2.1M on a "profit" of negative $250K.
This is obviously not the hottest issue out there, but it has to be a BIG issue for a decent amount of .com victims, and I believe it will become the "prescription drug" issue by the next election as the number of lower-income victims grow.