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The basics
The alternative minimum tax, or AMT, is a second federal calculation with its own deductions, exemption, and rates. The model compares that calculation with the regular federal bill and adds only the excess.
AMT is part of the tax calculation automatically; it is not a separate expense you need to enter.
Illustrative numbers
Compare, then pay the excess
Regular federal tax$30,000
Tentative minimum tax$34,000
Additional AMT$4,000
The combined amount is $34,000 in this simplified example, not $64,000. If the tentative minimum tax were lower, no extra AMT would be due.
Calculation transparency
How it works in MoneyWhatIf
- 01
The model removes deductions unavailable in the parallel calculation, applies the filing-status exemption and phaseout, then prices the remaining ordinary income on the AMT ladder.
- 02
Long-term gains and qualified dividends retain preferential treatment inside the parallel calculation. Rental depreciation-related gain also retains its modeled special-rate treatment.
- 03
Tax created by a withdrawal, conversion, or gain is evaluated against the settled year’s tax position. An action can increase AMT or reduce an AMT amount already present.
- 04
Inspect the Taxes page and the year’s tax breakdown when a marginal cost differs from the bracket you expected.
Keep in mind
Model limits
The model includes the AMT inputs it collects. It does not accept every Form 6251 adjustment, including an incentive-stock-option exercise bargain element.
It is not a complete AMT-credit carryforward or tax-return preparation system.
This explanation documents the planning model. It is educational, not individualized tax, legal, Medicare, or investment advice.
Where it appears
Where to use it
See this concept in context, with a guide to each page and its controls.
The words behind it
Related financial terms
Plain-English definitions, with 2026 figures and worked examples, from the financial terms glossary.