The AMT was designed for taxpayers who have certain types of income that receive favorable treatment, or who qualify for certain deductions. The most common factors that subject taxpayers to AMT are:
State and local income taxes, including property taxes
Personal exemptions and the standard deduction
Miscellaneous itemized deductions
Tax exempt interest income from specified private activity bonds
Income from exercising incentive stock options
Differences in tax basis of fixed business assets related to depreciation or sale of an asset
The AMT was designed to prevent high income taxpayers from tax breaks. The AMT was not adjusted for inflation or tax cuts until 2015 and the pool of middle income taxpayers being taxed by AMT kept growing.