AMT Calculator - Alternative Minimum Tax

AMT Calculator - Alternative Minimum Tax helps taxpayers with preference items, ISO exercises, and high itemized deductions turn scattered inputs into a defensible AMT estimate. The page is designed for practical analysis rather than abstract definition: enter the relevant source figures, then review both the headline result and the supporting metrics. Because the calculation is shown on the page, the result can be checked, repeated, and compared across scenarios instead of treated as a black box. The core formula is AMT due = max(0, tentative minimum tax - regular tax). The page adds selected preference items to regular taxable income to estimate AMTI, subtracts the 2024 exemption after phaseout, applies 26% and 28% AMT rates, estimates regular tax from ordinary brackets, and reports AMT only when tentative minimum tax is higher. Optional fields are left out when blank, and required fields must be positive where the denominator, principal, income, or time period would otherwise make the result meaningless. That behavior is useful for early planning because a partial case can still be modeled without pretending that every input is known. It also makes sensitivity analysis straightforward: change one assumption at a time and watch how the AMT estimate responds. Common use cases include checking ISO exercise exposure, estimating whether state and local tax add-backs matter, preparing year-end tax planning, reviewing depreciation adjustments, and understanding why high-income taxpayers can owe tax under a parallel system. In each case, the point is not just to produce a number, but to understand what drives that number. The most sensitive input depends on the metric: rates and terms drive time-value calculations, denominators drive per-unit metrics, deductions and exemptions drive tax estimates, and timing assumptions drive valuation or return measures. The examples below use realistic inputs and show the arithmetic outcome so the method is easy to audit. AMTI shows the income base under the parallel tax system, the exemption shows how much AMTI is shielded, and AMT due shows only the excess over estimated regular tax. The AMT estimate is most reliable when the inputs use the same period, entity, and accounting basis. Avoid mixing annual and monthly values, book and market values, pre-tax and after-tax figures, or gross and net amounts unless the label explicitly calls for that treatment. Capital gains, credits, detailed AMT forms, exact itemized deduction limits, and taxpayer-specific adjustments are simplified, so final AMT should be calculated with official forms or tax software. Use the result for education, screening, and scenario comparison, then verify consequential filings, financing choices, investment decisions, or contracts against authoritative source documents.