It's a complicated calculation. There is no fixed income level for it.The calculation takes the higher of Regular Tax or AMT.If you have high income, low itemized deduction, or you take the standard deduction, your Regular tax may be higher than AMT, then you pay the regular tax. So for some folks, paying AMT is not necessarily the bad thing. Or you have only median income (say 70k) but high deduction, then you will pay AMT because your AMT will be more than regular tax. The most optimal scenario is regular tax almost = AMT.
Understand the history of AMT, which is to try to provent rich people using large deduction to avoid taxes, will help you understand AMT.
