AMT Lookup Calculator

Check if you owe AMT from AMTI, exemption, and phase-out calculations.

By Konstantin Iakovlev · Updated September 2026 · Source: IRS Rev. Proc. 2025-32 §4.10 — 2026 AMT exemptions, phase-out thresholds and 28% breakpoint

$
$

Tentative Min Tax

$54,574.00

Additional AMT

$0.00

AMT Calculation

Exemption$90,100.00
AMT Base$209,900.00
Tentative Minimum Tax$54,574.00
Regular Tax (estimated, no AMT adjustments)$68,134.25
Additional AMT Owed$0.00

Use the AMT Lookup Calculator above to calculate your results. Enter your values and see instant results — all calculations run in your browser.

Disclaimer: This calculator is for informational purposes only and does not constitute tax, financial, or legal advice. Results are estimates based on the information you provide and current rates. Always consult a qualified tax professional or financial advisor for advice specific to your situation.

How It Works

The Alternative Minimum Tax runs as a parallel tax system, built to guarantee that high-income earners pay at least a floor amount even after stacking up deductions under the regular rules. An AMT lookup tells you whether you fall into that net and, if you do, roughly how much extra you owe.

Mechanically, the calculation pits two numbers against each other. Your tentative minimum tax, figured under AMT rules with their own adjustments and preference items, is compared to your regular tax liability. When the tentative minimum tax comes out higher, the gap between the two is your AMT. In effect, your tax base is rebuilt from scratch under a stricter rulebook.

Several items behave differently under AMT than under the regular system, and overlooking them throws the result off. State and local taxes (SALT) and incentive stock options (ISOs) are frequent culprits. Because the AMT exemption amounts and phase-out thresholds reset every year, the calculation only holds up if you feed it the current tax year's figures.

Example: A $150,000 Incentive Stock Option Spread

  1. 1 A single filer earns $300,000 and takes the $16,100 standard deduction, so regular taxable income is $283,900 and regular tax is $68,134. She also exercises incentive stock options with a $150,000 spread, which counts only for AMT. AMTI = $283,900 + $16,100 (the standard deduction is added back) + $150,000 = $450,000. Enter $450,000, Single, and $68,134 as regular tax.
  2. 2 AMTI is below the $500,000 phase-out threshold, so the full $90,100 exemption applies: $450,000 - $90,100 = $359,900. Tentative minimum tax = 26% of the first $244,500 ($63,570) + 28% of the remaining $115,400 ($32,312) = $95,882.
  3. 3 Her AMT is the difference: $95,882 - $68,134 = $27,748.
  4. 4 In this scenario, she would owe an additional $27,748 in tax due to the Alternative Minimum Tax, on top of her regular tax liability. Without the stock options, AMTI would be $300,000 and the tentative minimum tax $54,574, well under the regular tax, so no AMT. This highlights the importance of proactive tax planning if you anticipate being subject to AMT.

Source: IRS Rev. Proc. 2025-32 §4.10 — 2026 AMT exemptions, phase-out thresholds and 28% breakpoint · Last updated: September 2026

Frequently Asked Questions

How do I know if I owe the alternative minimum tax?
You may owe AMT if you have large state and local tax deductions or exercised incentive stock options. The AMT exemption for 2026 is $90,100 for single filers and $140,200 for married filing jointly.
What is the AMT exemption phase-out?
The AMT exemption begins to phase out at $500,000 for single filers and $1,000,000 for married filing jointly in 2026. For every dollar of AMTI above these thresholds, the exemption is reduced by 50 cents. Both the thresholds and the 50% phase-out rate were set by the One Big Beautiful Bill Act, so they are not inflation adjustments of the earlier figures.
What tax rate applies to AMT income?
AMT has two rates: 26% on the first $244,500 of AMTI above the exemption ($122,250 if married filing separately) and 28% on amounts above that threshold.

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