.A tax, often a flat rate, potentially imposed on corporations and
higher-income individuals to ensure that those taxpayers do not avoid too much (or all) income-tax liability by legitimately using exclusions, deductions, and credits. — Abbr. AMT. — Also termed minimum tax. [Cases: Internal Revenue 3550. C.J.S. Internal Revenue §§ 358–361.]

[Blacks Law 8th]