The difference between a taxpayer's alternative minimum taxable income and his AMT exemption is taxed using the relevant rate schedule. This yields the tentative minimum tax (TMT).

There would be a tax on the difference between the value of a taxpayer’s AMT exemption and AMTI. This results in the tentative minimum tax (TMT). A taxpayer with TMT higher than their regular tax liability will have to pay the regular tax for the year alongside the value for which the TMT rises above the regular tax.