AMT Calculator 2026 (alternative minimum tax: exemption, phase-out, 26% / 28%)

Understanding the AMT calculator — concept and principle

This calculator estimates the US alternative minimum tax (AMT) for 2026. From your regular taxable income, AMT adjustments and regular tax, it finds alternative minimum taxable income (AMTI), the exemption after phase-out, the tentative minimum tax and the AMT you owe. Use it to check whether large preference items, such as incentive stock options or certain deductions, might trigger AMT.

AMT is only the excess of the tentative minimum tax over the regular tax.

How it is calculated

AMTI = regular taxable income + AMT adjustments and preferences.
2026 exemption: $90,100 (single, head of household), $140,200 (joint), $70,100 (married separately), reduced by 50 cents per dollar of AMTI above $500,000 ($1,000,000 joint).
Tentative minimum tax = 26% of (AMTI − exemption) up to $244,500 ($122,250 married separately), 28% above.
AMT = tentative minimum tax − regular tax, if positive.

Simplified: all income is treated as ordinary, and credits are left out. If regular tax is entered as 0, the page estimates it from the 2026 brackets.

The principle

The AMT is a parallel tax system meant to ensure that taxpayers with many tax preferences still pay a minimum amount. You compute tax twice: once under the regular rules and once under AMT rules, which add back certain preferences and use a flat 26%/28% structure with a large exemption. You pay whichever is higher; the difference is the AMT. The exemption phases out at higher incomes, which is why AMT mainly affects upper-middle and high incomes with large adjustments.

Worked example

Default inputs: single, taxable income $250,000, adjustments $200,000, regular tax estimated.

AMTI = 250,000 + 200,000 = $450,000. This is below $500,000, so the full $90,100 exemption applies.
AMT base = 450,000 − 90,100 = $359,900.
Tentative tax = 26% × 244,500 + 28% × (359,900 − 244,500) = 63,570 + 32,312 = $95,882.
Regular tax (2026 brackets, estimated) = $56,456.
AMT = 95,882 − 56,456 = $39,426; total federal tax $95,882. The exemption would be fully phased out at AMTI $680,200.

Each point is the calculator re-run with only “AMT adjustments and preference items (USD)” changed; the gold point is the default example. Change the inputs above and this chart follows your numbers.

AMT adjustments and preference items (USD)	AMT you owe (USD)
50,000	0
100,000	11,426
150,000	25,426
200,000	39,426
250,000	53,426
300,000	74,426
400,000	116,426

How to read the result

If AMT is 0, the regular tax is higher and you pay no AMT. A positive figure is the extra tax on top of regular tax. Large one-time adjustments, such as the bargain element of exercised incentive stock options, are a common cause. Part of AMT paid may later be recovered as a credit in some cases, which this tool does not model.

Common mistakes

Entering adjusted gross income instead of taxable income.
Ignoring that qualified dividends and long-term gains get lower rates under the real AMT rules.
Assuming the exemption never phases out.

Keep in mind: This is a simplified estimate. The real calculation on Form 6251 has many special rules. Consult the IRS instructions or a qualified tax professional. This is not tax advice.

Frequently asked questions

Who has to pay AMT?

Anyone whose tentative minimum tax exceeds their regular tax, typically those with large preference items.

What triggers AMT most often?

Exercising incentive stock options and other large adjustments added back under AMT rules.

What is the 2026 AMT exemption for single filers?

$90,100, phased out by 50 cents per dollar of AMTI above $500,000.

Sources: IRS, Rev. Proc. 2025-32, sec. 4.10 (2026 AMT exemption amounts) · 26 U.S.C. § 55

Checked 9 Nov 2026. IRS Rev. Proc. 2025-32, sec. 4.10 “Exemption Amounts for Alternative Minimum Tax” (2026: 28% threshold 244,500 / 122,250 USD; exemptions 90,100 / 140,200 / 70,100 USD; phase-out thresholds 500,000 / 1,000,000 USD) and sec. 4.01 (2026 tax brackets); 26 U.S.C. § 55(b)(1) and (d)(4) as amended by Public Law 119-21 (26%/28% rates, 50% phase-out rate).

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