Alternative Minimum Tax: How It Works, Exemptions, and Credits

The alternative minimum tax is a parallel calculation of your federal income tax that disallows certain deductions, applies its own rates, and makes you pay whichever number comes out higher: your regular tax or the AMT result. For the 2026 tax year, single filers get an AMT exemption of $90,100 and married couples filing jointly get $140,200. If your recalculated income after AMT adjustments stays below your exemption, you owe no AMT.¹

How the Parallel Calculation Works

You compute your tax twice. Start with your regular taxable income, add back the deductions and preference items the AMT disallows, subtract your AMT exemption, and apply the AMT rates to what’s left. That figure is your tentative minimum tax. If it exceeds your regular tax, the difference is what you owe on top as AMT.

The deductions the AMT strips out are the ones most likely to shrink a high earner’s regular tax bill. State and local taxes, personal exemptions, and accelerated depreciation all get reversed. The question the system asks is whether, after removing those breaks, your income should have produced a larger tax bill.

2026 Exemption Amounts

The exemption functions like a large deduction that applies only inside this parallel calculation. For 2026, the IRS has set:¹

Single filers: $90,100
Married filing jointly or surviving spouse: $140,200
Married filing separately: $70,100
Estates and trusts: $31,400

These amounts adjust for inflation each year, which keeps the tax focused on higher earners rather than gradually reaching into middle incomes.

Phase-Out of the Exemption

The exemption shrinks once your alternative minimum taxable income (AMTI) crosses a threshold, at a rate of 50 cents lost for every dollar above the limit. For 2026:¹

Single filers: phase-out begins at $500,000; exemption fully gone at $680,200
Married filing jointly: begins at $1,000,000; fully gone at $1,280,400
Married filing separately: begins at $500,000; fully gone at $640,200

The phase-out is aggressive. A single filer with $600,000 in AMTI has already lost $50,000 of the $90,100 exemption, leaving roughly $40,100 as a buffer. Above the endpoint, every dollar of AMTI faces the AMT rates with no exemption at all.

What Gets Added Back to Your Income

The AMT calculation begins with your regular taxable income and adds back specific items. These are the adjustments and preference items that most often trigger AMT liability.

State and Local Taxes

The AMT eliminates the deduction for state and local income, sales, and property taxes entirely.² Every dollar you deducted on your regular return gets added back to AMTI. This is one of the most common reasons taxpayers in high-tax areas end up owing AMT.

Standard Deduction and Personal Exemptions

Both the standard deduction and personal exemptions are disallowed under the AMT.² Households with several dependents see a wider gap between regular taxable income and AMTI as a result.

Incentive Stock Options

This is where the AMT surprises people most often. When you exercise incentive stock options, the regular tax system waits until you sell the shares to recognize any income. The AMT does not wait. The spread between your exercise price and the stock’s fair market value at exercise counts as AMT income in the year you exercise.³ Exercising $200,000 worth of options with a $50,000 exercise price adds $150,000 to AMTI without any cash changing hands.

Private Activity Bond Interest

Interest on certain private activity bonds is tax-free under the regular income tax but counts as a preference item for AMT.⁴ Not all municipal bonds trigger this; it applies to bonds financing private projects like stadiums or industrial parks rather than traditional government infrastructure.

Depreciation and Mortgage Interest

Businesses and rental property owners using accelerated depreciation must recompute those deductions using the slower straight-line method for AMT, and the difference gets added back. Home mortgage interest is generally deductible under both systems if the loan was used to buy or improve your home. Interest on home equity debt used for unrelated purposes, like paying off credit cards, is disallowed under the AMT.

The AMT Rates

After subtracting the exemption from AMTI, you apply a two-tier rate:⁵

26% on the first $244,500 of taxable excess above the exemption
28% on everything beyond $244,500

For married individuals filing separately, the 28% rate starts at $122,250.¹ These thresholds also adjust for inflation.

Long-term capital gains and qualified dividends keep their preferential rates inside the AMT calculation.³ Investment gains are not taxed more heavily just because you owe AMT. They can, however, push your AMTI higher, which accelerates the phase-out of your exemption and pulls more ordinary income into the AMT rates.

Recovering AMT Through the Minimum Tax Credit

Paying AMT in one year does not always mean the money is gone. If the AMT resulted from timing differences rather than permanent tax breaks, you may recover some or all of it in future years through the minimum tax credit on IRS Form 8801.⁶

The distinction depends on whether the adjustment was a deferral item or an exclusion item. Deferral items, such as depreciation differences or the ISO spread, create a temporary mismatch between regular and AMT income. The income eventually gets recognized under both systems, and the earlier AMT you paid can be credited against your regular tax later. Exclusion items, such as the lost state and local tax deduction, create a permanent difference and generate no credit.⁷

The credit carries forward indefinitely. In any later year where your regular tax exceeds your tentative minimum tax, you can apply the credit to reduce what you owe. This is often meaningful for people who paid AMT because of an ISO exercise and later sold the shares.

Reporting the AMT

You report the AMT on IRS Form 6251, which walks through each adjustment and preference item.⁸ The form begins with your adjusted gross income, adds back disallowed deductions, subtracts the exemption, applies the AMT rates, and compares the result to your regular tax. Additional AMT owed transfers to Schedule 2 of Form 1040. Form 6251 must be attached to your return.

IRS systems flag returns where income levels suggest an AMT calculation should have been done. Skipping the form when it applies will generate follow-up correspondence. Underpaying because you failed to account for AMT carries the standard failure-to-pay penalty of 0.5% of the unpaid balance for each month it remains outstanding, up to a 25% maximum, plus interest.⁹ If you pay estimated taxes, your quarterly payments should reflect projected AMT liability as well.

Managing AMT Exposure

Most planning around the AMT comes down to timing. If you hold incentive stock options, spreading exercises across multiple years instead of concentrating them into one can keep AMTI under the exemption in each year. Running the projection before exercising matters because the tax bill can arrive before you have sold any shares to cover it.

For taxpayers in high-tax states, the complete loss of the state and local tax deduction under the AMT is unavoidable, but knowing it in advance lets you plan. When you are close to the threshold, accelerating income into one year or deferring deductions can sometimes tip the calculation. Years that include an ISO exercise, a property sale with significant depreciation recapture, or unusually large state tax payments deserve a side-by-side calculation of both the regular tax and the AMT before you file.

1
Internal Revenue Service. Revenue Procedure 2025-32
2
Office of the Law Revision Counsel. 26 US Code 56 – Adjustments in Computing Alternative Minimum Taxable Income
3
Internal Revenue Service. Topic No. 556, Alternative Minimum Tax
4
Office of the Law Revision Counsel. 26 US Code 57 – Items of Tax Preference
5
Office of the Law Revision Counsel. 26 Code 55 – Alternative Minimum Tax Imposed
6
Internal Revenue Service. About Form 8801, Credit for Prior Year Minimum Tax – Individuals, Estates, and Trusts
7
Internal Revenue Service. Instructions for Form 8801
8
Internal Revenue Service. About Form 6251, Alternative Minimum Tax – Individuals
9
Internal Revenue Service. Failure to Pay Penalty