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AMT (Alternative Minimum Tax) Calculator

Estimate U.S. alternative minimum tax from AGI, AMT add-backs, exemption phaseout, 26% and 28% AMT rates, credits, and regular tax.

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AMT estimate
Alternative minimum tax after credits
$14,262.00
Alternative minimum taxable income
$58,700.00
AMT exemption after phaseout
$81,300.00
Tentative minimum tax
$15,262.00
Extra AMT over regular tax
$2,262.00

Single in 2023: $140,000.00 AMTI less a $81,300.00 exemption leaves $58,700.00 taxed at AMT rates.

Your income before the AMT add-backs used in Form 6251.
$
Common add-backs include taxes and deductions that are not allowed for AMT.
$
Optional comparison amount to estimate extra AMT due above regular tax.
$
$

Results update as you type.

AMT (Alternative Minimum Tax) Calculator

The AMT calculator estimates U.S. alternative minimum tax using the inputs available in the form: tax year, filing status, adjusted gross income, AMT adjustments or add-backs, regular income tax before credits, and allowable AMT credits. It is intended for planning around Form 6251 concepts, not for filing. The calculator shows alternative minimum taxable income, the AMT exemption after phaseout, tentative minimum tax, AMT after credits, and any extra AMT above regular tax.

This is informational, not tax advice. IRS thresholds, exemptions, credits, and instructions can change, and actual AMT can require detailed adjustments not captured by a single add-backs field. The result is best used to understand sensitivity: how much do add-backs, filing status, credits, and regular tax change AMT exposure?

How to use the calculator

Choose the tax year and filing status. The calculator currently includes the embedded AMT tables for 2022 and 2023. Enter adjusted gross income (AGI) before AMT adjustments. Then enter the total of AMT adjustments/add-backs you want to test. This might include items that tax software or Form 6251 identifies as preferences or adjustments. Enter regular income tax before credits if you want the tool to show whether AMT creates extra tax above regular tax. Enter allowable AMT credits if applicable; credits reduce tentative minimum tax in this simplified model.

For broader planning, compare income assumptions with the salary calculator, test household cash flow with the budget calculator, and review debt pressure with the debt-to-income calculator. Those related tools do not calculate AMT, but they help you understand whether a tax estimate changes monthly decisions.

What AMT means

Alternative minimum tax is a parallel federal tax calculation. Congress designed it so that certain deductions and preference items cannot reduce tax below a separate minimum calculation. The first step is alternative minimum taxable income (AMTI). In this calculator, AMTI is simply AGI plus the add-backs you enter. Real Form 6251 can be more detailed, but the simplified structure makes the mechanics visible.

After AMTI is calculated, the tool subtracts the AMT exemption for the selected filing status and year. The exemption phases out at 25 cents per dollar of AMTI above the phaseout threshold in this simplified model. The remaining taxable AMT income is taxed at 26% up to the AMT rate break and 28% above that break. Credits then reduce tentative minimum tax. Finally, AMT after credits is compared with regular tax. Only the amount above regular tax is displayed as extra AMT exposure.

Formula

AMTI=AGI+AMT add-backs\text{AMTI} = \text{AGI} + \text{AMT add-backs}

phaseout reduction=max⁡(0,AMTI−phaseout threshold)×25%\text{phaseout reduction} = \max(0, \text{AMTI} - \text{phaseout threshold}) \times 25\%

exemption=max⁡(0,base exemption−phaseout reduction)\text{exemption} = \max(0, \text{base exemption} - \text{phaseout reduction})

taxable AMT income=max⁡(0,AMTI−exemption)\text{taxable AMT income} = \max(0, \text{AMTI} - \text{exemption})

AMT after credits=max⁡(0,tentative minimum tax−credits)\text{AMT after credits} = \max(0, \text{tentative minimum tax} - \text{credits})

Example

Using the default inputs, choose 2023, Single, $120,000 of AGI, $20,000 of AMT add-backs, $12,000 of regular tax, and $1,000 of credits. AMTI is $140,000. The 2023 single exemption used by the selected historical model is $81,300, and the phaseout threshold is $578,150. Because AMTI is below the phaseout threshold, the phaseout reduction is $0 and the exemption remains $81,300.

Taxable AMT income is $58,700. That amount is below the 2023 single AMT rate break in the calculator, so it is taxed entirely at 26%. Tentative minimum tax is $15,262. After the $1,000 credit, AMT after credits is $14,262. Compared with $12,000 of regular tax, the calculator shows $2,262 of extra AMT over regular tax. These numbers match the calculation exactly.

Who this affects

AMT can matter for taxpayers with large preference items, certain incentive stock option exercises, high state and local tax deductions under regular tax, unusual depreciation differences, or other items that produce a gap between regular tax and AMT. This simplified calculator is especially useful when you already have an estimated add-back total and want to see how the exemption phaseout and AMT brackets respond.

It is less suitable when you do not yet know the add-backs. In that case, the official IRS form and instructions are the right starting point. Also remember that the calculator supports only the years listed in the form. Do not use a 2023 table as if it automatically applies to a later year.

The comparison with regular tax is also important. A taxpayer can have a positive tentative minimum tax and still owe no extra AMT if regular tax is higher. Conversely, a modest change in credits or add-backs can move AMT after credits above regular tax. When using the tool for planning, keep the regular-tax input aligned with the same year, filing status, and income assumptions used for the AMT inputs.

Sources

Frequently asked questions

What does the AMT calculator estimate?
It estimates alternative minimum taxable income, the AMT exemption after phaseout, tentative minimum tax, AMT after allowable credits, and extra AMT above regular tax. It mirrors the simplified calculation rather than every line of IRS Form 6251 instructions exactly.
What are AMT add-backs?
AMT add-backs are deductions or preference items treated differently under the alternative minimum tax system than under regular tax. This calculator lets you enter them as one combined amount. Form 6251 and its instructions are the official references for identifying actual adjustments.
How does the AMT exemption phaseout work here?
The calculator starts with the selected year's exemption for the filing status. It reduces that exemption by 25% of AMTI above the phaseout threshold. The exemption cannot go below zero, so high AMTI can eliminate it entirely in this simplified model.
Why do I enter regular tax?
Regular tax is used only to estimate extra AMT exposure. The calculator first computes AMT after credits, then compares it with regular income tax before credits. If AMT after credits is higher, the difference appears as extra AMT over regular tax.
Which years are supported?
The form currently supports the 2022 and 2023 AMT exemption, phaseout, and rate-break amounts embedded in the calculator model. Later tax years require updated IRS figures before the estimate should be used for current filing decisions or planning work.

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