The individual alternative minimum tax (AMT) was originally enacted in 1969 to guarantee that high-income individuals paid at least a minimal amount of tax. Middle- and upper-income taxpayers must add a number of so-called preference items to their taxable income, subtract a special AMT exemption, and calculate their tax according to the AMT tax schedule. If the tax under that schedule is higher than the regular income tax, taxpayers pay the difference as AMT. This document outlines 11 key facts and projections about the AMT, including its effects on taxpayers and prospects for its reform.