What this calculator answers
This tool estimates 2026 federal Alternative Minimum Tax for an individual using the ordinary 26% and 28% tentative-minimum-tax path after two return-level amounts have been established. It applies the filing-status exemption, reduces that exemption inside the 2026 phaseout range, calculates tentative minimum tax, and compares it with supported regular tax.
It does not construct alternative minimum taxable income from raw wages, deductions, stock-option documents, partnership items, or investment statements. It also does not handle the preferential-rate worksheet for qualified dividends and capital gains, the alternative minimum tax foreign tax credit, excluded foreign income, kiddie-tax exemption limit, or special return calculations. Those issues can change the Form 6251 arithmetic before the final comparison.
AMT is the excess over regular tax, not a second full tax bill
The alternative system recalculates income using different treatment for specified deductions, income, adjustments, and preference items. After an allowed exemption and the AMT rate calculation, Form 6251 produces tentative minimum tax. Alternative Minimum Tax is generally the amount by which tentative minimum tax after the applicable AMT foreign tax credit exceeds the regular tax amount used on Form 6251.
If tentative minimum tax is $135,000 and the supported regular-tax comparison amount is $120,000, the estimated AMT is $15,000. The taxpayer does not ordinarily add the entire $135,000 to the $120,000. If regular tax is already equal to or greater than tentative minimum tax, the simplified AMT estimate is zero even though Form 6251 may still be relevant for filing, credit, or record purposes.
2026 individual AMT exemption amounts
For 2026, the statutory exemption is $90,100 for single and head-of-household filers, $140,200 for married couples filing jointly and qualifying surviving spouses, and $70,100 for married individuals filing separately. These amounts reduce alternative minimum taxable income only to the extent the exemption remains after the phaseout calculation.
The exemptions are not deductions carried from Form 1040, and they are not the standard deduction. The ordinary 2026 standard deduction and the AMT exemption have different amounts, purposes, and rules. Entering ordinary taxable income in place of AMTI can miss the very adjustments that make the AMT calculation necessary.
The 2026 exemption phaseout uses 50%, not 25%
Public Law 119-21 changed the AMT exemption phaseout percentage from 25% to 50% for tax years beginning after December 31, 2025. The allowed exemption is reduced by 50 cents for each dollar of AMTI above the applicable 2026 phaseout threshold, until the exemption is fully eliminated. Reusing a 2025 calculator can therefore materially understate how quickly the 2026 exemption disappears.
For single, head-of-household, and married-filing-separately taxpayers, phaseout begins when AMTI exceeds $500,000. For married filing jointly and qualifying surviving spouse, phaseout begins above $1,000,000. The exemption is fully phased out at $680,200 for unmarried individuals other than surviving spouses, $1,280,400 for joint filers and surviving spouses, and $640,200 for married filing separately.
A single filer with $600,000 of supported AMTI is $100,000 into the phaseout range. The $90,100 base exemption is reduced by $50,000, leaving $40,100. A 25% phaseout shortcut would incorrectly leave $65,100. Showing this step separately is one of the most important reasons to use a 2026-specific calculation.
The 26% and 28% AMT rate breakpoints
After subtracting the allowed exemption from AMTI, but not below zero, the result is taxable excess. For 2026, the 26% AMT rate applies to the first $244,500 of taxable excess for taxpayers other than married filing separately. The 28% rate applies above that amount. For married filing separately, the corresponding breakpoint is $122,250.
The 28% rate is not applied to all AMTI merely because taxable excess crosses the breakpoint. The first band remains taxed at 26%, and only the amount above the breakpoint is taxed at 28%. For ordinary-rate cases, the same arithmetic can be expressed as 28% of taxable excess minus $4,890 for most filers, or minus $2,445 for married filing separately, once the breakpoint is exceeded. The calculator displays the bands instead of relying on the compressed shortcut.
Alternative minimum taxable income must come from Form 6251 work
AMTI begins with return information and then applies the adjustments and preferences required by Form 6251. Depending on the facts, those can involve the standard deduction, state and local tax deductions, investment interest, depletion, depreciation, passive activities, loss limitations, private activity bond interest, incentive stock options, qualified small business stock, partnership or S corporation items, tax shelters, and other specialized calculations.
Some adjustments can be negative. An AMT basis can differ from regular-tax basis, and a later disposition can reverse or alter an earlier adjustment. A page that simply adds a handful of common items to adjusted gross income can look convenient while omitting the controlling form lines. That is why this calculator requires supported Form 6251 line 4 AMTI rather than pretending to prepare Part I from incomplete facts.
For married filing separately, Form 6251 can require a special addition to line 4 at high income. The exact 2026 instructions must be used before entering the supported line 4 amount. This calculator applies the published 2026 exemption profile to the entered final line 4 figure; it does not invent the preceding married-separate adjustment.
Incentive stock options can create an AMT adjustment
For regular federal income tax, exercising a qualifying incentive stock option generally does not create ordinary income at exercise. For AMT, the excess of the stock’s fair market value over the exercise price can become an adjustment when the acquired rights are transferable or no longer subject to a substantial risk of forfeiture. The adjustment generally increases AMTI and AMT basis.
No ISO adjustment is generally required when the stock is disposed of in the same year as exercise, but disqualifying dispositions, holding periods, restrictions, later sales, basis differences, capital-loss rules, and compensation reporting can make the complete result more complicated. An “ISO spread × AMT rate” shortcut is not the same as Form 6251 because the exemption, phaseout, rate bands, regular-tax comparison, and other return items still matter.
Use employer option records, exercise confirmations, Form 3921, vesting and transferability facts, sale documents, and the current Form 6251 instructions to establish the actual line 2i adjustment and final line 4 AMTI. For one supported vested-at-exercise Form 3921 lot, the 2026 ISO AMT Adjustment Calculator removes same-year dispositions and shows the positive spread, retained-share exercise cost, line 2i input, and modeled AMT basis. When an identified ISO lot is sold during 2026, the 2026 ISO Sale Tax and AMT Basis Calculator separates regular compensation and capital gain from the distinct AMT basis result without presenting its raw difference as final line 2k. The 2026 Stock Compensation Tax Guide connects the exercise and sale records with payment planning and employer-stock risk. Then use this AMT calculator only if the ordinary-rate suitability path remains valid.
Capital gains and qualified dividends need Part III
The IRS permits qualifying dividends and certain capital gains to retain applicable preferential rates in the AMT calculation when those rates are lower than the regular AMT rates. Form 6251 Part III coordinates the AMT version of the qualified-dividend and capital-gain computation. Different AMT basis or loss carryovers can require an AMT Form 8949, Schedule D, or related worksheet.
This calculator stops for that path because applying 26% or 28% to all taxable excess can overstate tentative minimum tax. The 2026 Long-Term Capital Gains Tax Calculator models a simplified regular federal preferential-rate calculation, but its result cannot substitute for the AMT Part III worksheet. Use the official Form 6251 instructions and complete the AMT versions required by the return.
Foreign tax and foreign earned income need separate worksheets
The alternative minimum tax foreign tax credit has its own limits and can require AMT versions of Form 1116. A prior simplified-limitation election can affect the procedure. The credit reduces tentative minimum tax before the comparison with regular tax, so ignoring a valid AMT foreign tax credit could overstate AMT.
Taxpayers using the foreign earned income exclusion, housing exclusion, or housing deduction on Form 2555 must use the foreign earned income worksheet in the Form 6251 instructions. This calculator stops rather than silently applying the domestic ordinary-rate formula to a return that needs either calculation.
Regular tax means the Form 6251 comparison amount
The second money input is not total tax, withholding, estimated payments, refund, or balance due. Use the regular-tax amount established under the Form 6251 line 10 instructions. Foreign tax credit, Schedule J income averaging, tax from certain children’s income, lump-sum distribution tax, partner reporting adjustments, and nonresident-return rules can change what belongs on that line.
The 2026 Federal Income Tax Bracket Calculator calculates a simplified ordinary rate-schedule amount from taxable income; that result is not automatically Form 6251 line 10. Withholding and estimated payments are payments toward the complete return liability. They do not reduce tentative minimum tax or the line 10 regular-tax comparison. After the AMT amount is carried into the broader projected total tax, use the 2026 Quarterly Estimated Tax Calculator for a separate general safe-harbor payment analysis.
Three useful 2026 examples
AMTI below the exemption
A single filer has $80,000 of supported AMTI. The full $90,100 exemption remains available, so taxable excess is zero and tentative minimum tax is zero under this simplified path. No AMT results from the comparison, regardless of a non-negative regular-tax amount.
Exemption remains but is partially phased out
A single filer has $600,000 of AMTI. The $90,100 exemption is reduced by $50,000 because AMTI is $100,000 above the $500,000 phaseout threshold and the 2026 reduction rate is 50%. Taxable excess is $559,900. The first $244,500 is taxed at 26% and the remaining $315,400 at 28%, producing $151,882 of tentative minimum tax before the regular-tax comparison.
Joint exemption is fully phased out
A married couple filing jointly has $1,300,000 of AMTI. That exceeds the $1,280,400 complete-phaseout point, so no exemption remains. The ordinary-rate tentative minimum tax is 26% of the first $244,500 plus 28% of the remaining $1,055,500, or $359,110. The AMT itself still depends on subtracting the supported Form 6251 line 10 regular tax.
AMT can affect later-year records and credits
Paying AMT in one year can produce a potential minimum tax credit for a later year, particularly when the AMT came from a deferral item. Form 8801 determines whether a credit is available and how much can be used. Not every AMT component produces the same later benefit, and this calculator does not estimate the credit.
Maintain separate regular-tax and AMT basis records for assets when an adjustment creates a difference. ISO shares are a common example. Without the AMT basis adjustment, a later sale can be calculated incorrectly and the return may miss a negative AMT adjustment or misstate capital gain or loss.
The 2026 Net Investment Income Tax Calculator and 2026 Additional Medicare Tax Calculator cover other separate high-income taxes. AMT, NIIT, and Additional Medicare Tax use different income definitions, thresholds, rates, and forms. Carry each supported result into a complete return only once.
Why this tool asks for two totals instead of a wall of adjustments
Form 6251 Part I is a reconciliation system, not a generic income checklist. A long page of boxes for state taxes, options, bonds, depreciation, passive losses, partnership items, and deductions would still omit facts needed to determine whether each amount is positive, negative, deferred, duplicated elsewhere, or subject to a separate worksheet.
The four-step path first rejects calculations that need preferential-rate, foreign, child, entity, or special-return rules. It then makes the 2026 filing profile visible, confirms that the two source amounts are supported, and exposes only AMTI and regular tax together. The result shows each exemption and rate step so users can audit the arithmetic without mistaking the calculator for return preparation.
A practical record checklist
Retain the projected or filed Form 1040 and Form 6251, Schedule A, Forms 1116 and 2555 when relevant, Schedules K-1, Forms 3921, option exercise and sale records, regular and AMT basis schedules, Forms 1099, depreciation worksheets, passive-activity and loss carryovers, private activity bond information, prior Forms 6251 and 8801, and the instructions used for the calculation.
For planning, preserve a baseline Form 6251 and a revised version after one proposed transaction. Compare the final AMTI, allowed exemption, tentative minimum tax, regular tax, and AMT—not merely the transaction’s headline income. Rerun the broader return, payment, and cash-flow projections when the transaction changes regular tax, capital gains, NIIT, withholding, or state tax.
Official sources and the 2026 filing caveat
The official 2026 exemption amounts, 26%–28% breakpoints, phaseout thresholds, and complete-phaseout amounts are published in IRS Revenue Procedure 2025-32 and the Internal Revenue Bulletin 2025-45. The 50% phaseout change comes from section 70107 of Public Law 119-21.
The purpose of the tax, filing guidance, adjustment rules, ISO treatment, preferential-gain worksheet, AMT foreign tax credit, and regular-tax comparison come from IRS Topic No. 556, the Instructions for Form 6251, About Form 6251, Topic No. 427 on stock options, and Publication 525.
As of July 27, 2026, the detailed individual Form 6251 instructions identified on the IRS site are the 2025 revision; final 2026 individual instructions were not identified. This calculator uses enacted and officially published 2026 parameters with the current ordinary-rate mechanics for planning. Check the final 2026 Form 6251 and instructions before filing.
This calculator provides educational federal arithmetic for a supported 2026 individual ordinary-rate AMT scenario. It is not tax preparation, tax, legal, accounting, investment, equity-compensation, or financial advice. It does not determine AMTI, adjustments, preference items, filing status, exemption eligibility, regular tax, capital-gain treatment, AMT foreign tax credit, ISO treatment, basis, minimum tax credit, withholding, estimated payments, penalties, refund, balance due, state tax, or filing obligations. Verify every input and result with current IRS forms, instructions, records, software, and qualified guidance before filing, exercising or selling options, investing, or paying tax. Official sources were accessed July 27, 2026.