The Alternative Minimum Tax, or AMT, is a separate tax calculation that runs parallel to the regular income tax system. It exists because Congress wanted to may support that high-income taxpayers pay at least some federal tax, even when deductions, credits, or certain types of income reduce their regular tax bill to very low levels. The AMT recalculates your tax using a different set of rules—it disallows or limits many deductions and adds back certain income items—then compares the result to your regular tax. If the AMT is higher, you pay that amount instead.
Most taxpayers never encounter the AMT, but it affects those with substantial income, significant deductions (like state and local taxes), or certain types of investments. The articles here explain how the AMT calculation works, which situations trigger it, and how it interacts with credits and deductions you may already claim. Understanding whether the AMT applies to you helps clarify your actual tax liability and why your tax bill might be higher than expected.