The tax law provides exclusions for certain kinds of income, deductions, and credits for certain expenses. The alternative minimum tax (AMT) attempts to ensure that an individual who benefits from certain exclusions, deductions, or credits pays at least a minimum amount of tax.
The AMT is a separately figured tax that eliminates or reduces many exclusions and deductions. In addition, certain credits (generally, business-related credits) cannot be used to offset the AMT. Thus, the AMT increases the tax liability of an individual who would otherwise pay less tax. The AMT tax rates on ordinary income are percentages set by law. For capital gains and certain dividends, the rates in effect for the regular tax are used.