Alternative Minimum Tax Calculator - 2026 AMT Estimate

The alternative minimum tax calculator estimates whether a federal individual income tax return may owe AMT after adjustments, the annual exemption, the exemption phaseout, the 26 percent and 28 percent AMT rates, and the regular-tax comparison are considered. It supports planning discussions, tax projection reviews, incentive stock option analysis, and year-end estimate checks.

AMT is a parallel tax calculation. A taxpayer first calculates regular tax under the ordinary rules, then calculates tentative minimum tax under Form 6251-style rules. Additional AMT appears only when tentative minimum tax is higher than regular tax. That comparison is why the calculator asks for regular tax instead of looking only at income.

The model begins with regular taxable income and adds AMT adjustments or preference items to estimate alternative minimum taxable income, often shortened to AMTI. Examples can include exercised-and-held incentive stock option spread, private activity bond interest, certain depreciation differences, or deductions that receive different treatment under AMT. The calculator does not decide which adjustments apply; it turns entered values into an AMT estimate.

This page is most helpful before a filing return is complete. It can show whether a planned ISO exercise, a large capital event, or a deduction-heavy return might require closer Form 6251 review. It can also compare 2025 and 2026 AMT thresholds, which changed under IRS inflation adjustments and later law changes.

The result is intentionally framed as an estimate. It does not recreate every Form 6251 line, does not calculate regular income tax from scratch, and does not allocate qualified dividends or long-term capital gains through the AMT capital gain worksheet. Its role is to make the main AMT mechanics visible before a taxpayer or preparer moves into full return software.

For the ordinary federal tax side of the comparison, the federal income tax calculator can estimate regular tax before the AMT comparison is made.

The calculator follows the main individual AMT sequence: estimate AMTI, reduce the annual exemption when AMTI is above the phaseout threshold, subtract the remaining exemption, apply AMT rates, subtract any AMT foreign tax credit entered, and compare the result with regular tax.

AMTI equals regular taxable income plus AMT adjustments and preference items. The allowed exemption starts at the annual exemption amount for the selected filing status. If AMTI exceeds the phaseout threshold, the exemption is reduced by 25 percent of the excess. The exemption cannot fall below zero.

Taxable excess is AMTI minus the allowed exemption. The first AMT bracket is taxed at 26 percent and the amount above the annual breakpoint is taxed at 28 percent. For 2026, the calculator uses a $244,500 breakpoint for most filing statuses and $122,250 for married filing separately. For 2025, it uses $239,100 and $119,550.

A simplified worked example shows the order. A single 2026 projection with $500,000 of taxable income and $150,000 of AMT adjustments has $650,000 of AMTI. The $90,100 exemption is reduced by 25 percent of the $150,000 amount above the $500,000 phaseout threshold, leaving a $52,600 exemption. Taxable excess is $597,400, which produces $162,382 of tentative minimum tax before the regular-tax comparison.

If regular tax in that example is $120,000, estimated AMT owed is $42,382. If regular tax were $170,000, estimated AMT owed would be zero because regular tax would already exceed tentative minimum tax. This is the key reason AMT projections must include both tracks.

According to IRS Topic No. 556, AMT applies to taxpayers with high economic income by limiting certain benefits and is figured by comparing tentative minimum tax with regular tax. This calculator keeps that comparison visible in the results panel.

When capital gains or investment income drive the projection, the capital gains tax calculator can help separate regular capital gain tax from the AMT estimate.

AMT projections become clearer when the major terms are separated. Each term in the calculator represents a different stage of Form 6251-style reasoning.

For incentive stock option planning, the AMT adjustment is often the spread between fair market value and exercise price for shares exercised and held beyond the same tax year. That adjustment can create AMTI without immediate cash from a sale, which is why projections should be treated carefully.

The phaseout also changes the effective marginal cost of additional AMTI. While the AMT rate structure says 26 percent and 28 percent, income inside the exemption phaseout zone can reduce the exemption by another 25 cents per dollar. That reduction increases taxable excess, so an additional dollar of AMTI can expose more than one dollar to AMT rates during the phaseout range.

For broader investment-return context, the percentage return calculator can frame the pretax return before AMT and regular tax effects are reviewed.

The calculator includes 2025 and 2026 values because AMT planning often crosses filing seasons. The 2025 settings align with the IRS 2025 Form 6251 instructions. The 2026 settings use IRS inflation-adjusted figures released for tax year 2026.

For 2026, the exemption is $90,100 for single and head-of-household filers, $140,200 for married filing jointly, and $70,100 for married filing separately. The phaseout starts at $500,000 for single, head-of-household, and married-filing-separately filers, and $1,000,000 for married filing jointly.

For 2025, the exemption is $88,100 for single and head-of-household filers, $137,000 for married filing jointly, and $68,500 for married filing separately. The phaseout starts at $626,350 for single, head-of-household, and married-filing-separately filers, and $1,252,700 for married filing jointly.

The exemption phaseout can fully remove the exemption when AMTI is far enough above the phaseout threshold. Because the reduction is 25 percent of excess AMTI, a $90,100 exemption is fully phased out after $360,400 of excess over the threshold. The calculator applies that cap automatically by never allowing a negative exemption.

The IRS 2026 tax inflation adjustment release lists the 2026 AMT exemption amounts and phaseout starting points used in this calculator.

Inflation-adjusted rules can change regular tax alongside AMT. The inflation calculator offers context for dollar-value changes when comparing thresholds across years.

The calculator expects inputs that are already organized for an AMT estimate. A tax projection worksheet, return draft, brokerage ISO report, or tax software summary can provide the regular taxable income, AMT adjustments, and regular tax figures.

1. 1The tax year sets the exemption, phaseout threshold, and AMT rate breakpoint for the projection year.
2. 2The filing status should match the status expected on the federal return or projection.
3. 3Regular taxable income is entered first, followed by AMT adjustments and preference items as a combined positive amount.
4. 4Regular tax before AMT and any AMT foreign tax credit are included before the final comparison.
5. 5The result panel shows AMTI, the allowed exemption, taxable excess, tentative minimum tax, and estimated AMT owed.

If the result changes sharply after a small adjustment, the projection may be near the exemption phaseout zone or the 28 percent breakpoint. Those cases deserve a closer Form 6251 review because marginal effects can be steeper than the headline AMT rates suggest.

Inputs should be documented outside the calculator. For ISO cases, that usually means grant records, exercise confirmations, fair market value at exercise, and sale records if any shares were sold during the year. For deduction adjustments, that may mean itemized deduction schedules and tax software summaries showing which deductions were added back on the AMT track.

For income inputs that need annualizing before AMT review, the annual income calculator can convert pay patterns into an annual figure.

An AMT estimate is useful when the ordinary tax picture looks incomplete. The calculator is not a substitute for return preparation, but it can identify when the AMT track deserves attention before a transaction or filing deadline.

• • It separates AMTI from regular taxable income, which helps document which adjustment amount is driving the result.
• • It shows how much of the annual exemption remains after phaseout, instead of treating the exemption as all-or-nothing.
• • It reports tentative minimum tax and the final AMT comparison, reducing confusion between the two measures.
• • It supports 2025 and 2026 review, which helps planning conversations that occur before final return forms are filed.
• • It gives ISO, investment, and high-deduction scenarios an early reasonableness check before detailed tax software entry.

AMT planning is especially relevant when a taxpayer has a large timing item. Exercised-and-held incentive stock options are the classic example, but investment interest, private activity bond interest, depreciation adjustments, and deduction differences can also matter. The calculator is best used as a screening tool that points to the next documentation step.

The estimate can also help with cash planning. Some AMT events, especially ISO exercises, can create tax without a matching liquidity event. Seeing tentative minimum tax before a transaction is completed can support a decision about exercise size, withholding, estimated tax payments, or whether shares may need to be sold before year-end.

When fees or tax drag are part of a broader portfolio review, the investment fees calculator can show how non-tax costs interact with after-tax planning.

The largest result changes usually come from AMTI, exemption phaseout, regular tax, and special items that the simplified model does not fully itemize. A projection should keep those limits visible.

Qualified-rate income is the biggest limitation in many investment-heavy returns. Form 6251 can preserve preferential treatment for qualified dividends and long-term capital gains through a separate worksheet. This calculator focuses on ordinary AMT taxable excess, so a return with large qualified-rate income may need a more detailed worksheet calculation.

The IRS Instructions for Form 6251 list adjustment lines, exemptions, AMT rate rules, and filing details that may affect a final return calculation. Those instructions should govern when a projection moves into filing work.

Retirement contributions can affect taxable income before AMT is projected. The 401k calculator can help frame contribution scenarios that may also change regular tax inputs.