Alternative Minimum Tax Calculator
Alternative Minimum Tax Calculator
Your total income after above-the-line deductions (Line 11 of Form 1040)
Tax before credits from your tax return. If blank, we estimate from your AGI and filing status.
Tax Credits (Reduce AMT)
AMT paid in prior years due to deferral items (like ISO exercises) that is now creditable against regular tax
Enter Your Tax Information
Fill in your AGI and filing status to instantly see whether you owe Alternative Minimum Tax and your full AMT breakdown for 2024 or 2025.
Important
This calculator is provided for general information only and is not financial, tax, or legal advice. Results are estimates and do not reflect your full circumstances, current rates, fees, or eligibility rules. Speak to a qualified professional before making a financial decision.
Calculate your AMT liability for 2024 and 2025 — including ISO stock options, SALT add-backs, and exemption phase-out
The Alternative Minimum Tax (AMT) is a parallel tax system designed to ensure that high-income individuals pay at least a minimum amount of federal income tax, regardless of deductions and credits available under the regular tax system. Originally enacted in 1969 to prevent wealthy taxpayers from using legal loopholes to avoid taxes entirely, the AMT operates alongside the regular income tax — you calculate both and pay whichever is higher. The AMT functions by eliminating many of the deductions and exclusions allowed under the regular tax code and adding back certain tax preference items. The result is your Alternative Minimum Taxable Income (AMTI). After subtracting an AMT-specific exemption (which phases out at higher income levels), you apply a flat rate of 26% or 28% to arrive at your Tentative Minimum Tax. If this amount exceeds your regular tax liability, you owe the difference as AMT. Under the Tax Cuts and Jobs Act of 2017 (TCJA), Congress dramatically increased AMT exemption amounts and phase-out thresholds, sharply reducing the number of AMT filers from approximately 5 million to fewer than 200,000. For 2025, the exemption is $88,100 for single filers and $137,000 for married filing jointly, with phase-outs starting at $626,350 and $1,252,700 respectively. These generous amounts are scheduled to expire after December 31, 2025, unless Congress acts — making AMT planning especially critical right now. The most common triggers for AMT in today's environment are Incentive Stock Options (ISOs) and private activity bond interest. When you exercise ISOs, the bargain element — the difference between the fair market value and the strike price times the number of shares — is not income for regular tax purposes but is fully added back as a preference item under AMT. This 'phantom income' can push many equity compensation recipients into significant AMT liability despite their regular tax being unaffected. Other AMT preference items include state and local tax (SALT) deductions, which are fully disallowed under AMT; miscellaneous itemized deductions subject to the 2% AGI floor; standard deductions; and accelerated depreciation differences. If you itemize deductions heavily or have large state income tax deductions, you may face AMT even without ISO exercises. This calculator implements the official IRS Form 6251 methodology, including the 5-step calculation process: computing AMTI by adding back preference items, applying the exemption with the 25-cents-per-dollar phase-out, computing AMT taxable income, applying the 26%/28% bracket rates while preserving preferential rates on long-term capital gains and qualified dividends, and finally determining how much (if any) AMT you owe above your regular tax. It also tracks AMT credit carryforward — the portion of AMT paid due to deferral items (like ISOs) that creates a minimum tax credit usable in future years when your regular tax exceeds your AMT.
Understanding the Alternative Minimum Tax
What Is the Alternative Minimum Tax?
The Alternative Minimum Tax (AMT) is a separate federal tax system that runs in parallel with the regular income tax. Taxpayers must calculate their liability under both systems and pay the higher amount. The AMT was created because certain tax preferences and deductions allowed under the regular code could dramatically reduce — or even eliminate — a high-income taxpayer's tax bill. By requiring everyone to pay at least a minimum tax, Congress intended to ensure that taxpayers with substantial economic income contribute meaningfully to federal revenue. The AMT uses a broader definition of income (AMTI) that includes items excluded from regular taxable income, most notably ISO stock option spreads and private activity bond interest. It then applies flat rates of 26% or 28% rather than the graduated bracket system of the regular tax, after a generous exemption that phases out at higher income levels.
How Is the AMT Calculated?
The AMT calculation follows five steps. First, start with your regular taxable income and add back all AMT preference items: state and local taxes you deducted, ISO bargain elements, private activity bond interest, miscellaneous itemized deductions, standard deductions (if taken), excess depreciation, percentage depletion excess, and non-acquisition home equity interest. The result is your Alternative Minimum Taxable Income (AMTI). Second, subtract your AMT exemption — $88,100 for single, $137,000 for MFJ in 2025 — but note the exemption phases out at 25 cents per dollar above the phase-out threshold. Third, the remaining amount is your AMT taxable income. Fourth, apply 26% on the first $239,100 (2025) and 28% above that, preserving preferential 15% rates on long-term capital gains and qualified dividends. Fifth, compare the resulting Tentative Minimum Tax against your regular tax — if TMT exceeds regular tax, you owe the difference as AMT.
Who Is Affected and Why It Matters
While the TCJA dramatically reduced AMT exposure for most Americans, several groups remain at significant risk. ISO exercisers are the largest group — the bargain element at exercise (FMV minus strike price times shares) creates immediate AMT income even though it doesn't appear on W-2 or trigger regular tax until shares are sold. A single large exercise can trigger AMT of tens or hundreds of thousands of dollars. High earners with large SALT deductions face exposure if they itemize state income taxes, property taxes, or both. People receiving substantial private activity bond interest from municipal bonds may find that interest is taxable under AMT. Business owners and real estate investors using accelerated MACRS depreciation face an adjustment for the difference between MACRS and AMT depreciation. Understanding whether you're subject to AMT is also important for planning purposes — you may be able to time ISO exercises, defer income, or accelerate deductions to minimize AMT liability.
Limitations and Important Notes
This calculator provides estimates based on the inputs you provide and official IRS parameters for 2024 and 2025. Several important limitations apply. First, the regular tax comparison uses a simplified bracket calculation from AGI minus standard deduction — for accuracy, enter your actual regular tax liability from tax software or Form 1040. Second, long-term capital gains within AMT receive preferential rates (this calculator uses 15% — your actual rate may be 0% or 20% depending on income). Third, the AMT credit carryforward calculation is an approximation — only AMT paid attributable to deferral items (like ISOs) generates future credits, while exclusion items (like SALT) do not. Fourth, state AMT rules vary and are not included here. Fifth, business and corporate AMT rules differ significantly from individual AMT covered here. Always consult a qualified tax professional for personalized advice, especially for ISO exercises, which can create complex multi-year AMT scenarios.
How to Use the AMT Calculator
Enter Your Basic Information
Select your tax year (2024 or 2025) and filing status, then enter your Adjusted Gross Income (AGI) from Line 11 of your Form 1040. If you know your regular tax liability, enter it too — otherwise, the calculator estimates it automatically from your AGI and filing status.
Add Your AMT Preference Items
Click 'AMT Preference Items & Add-Backs' to expand the section. Enter any state and local taxes (SALT) you deducted, private activity bond interest, depreciation adjustments, miscellaneous itemized deductions, and other items that are disallowed or added back under AMT rules.
Enter ISO Stock Option Details (if applicable)
If you exercised Incentive Stock Options (ISOs) during the year, click the 'ISO Stock Options' section and enter the number of shares exercised, the fair market value (409A valuation) at exercise, and your strike price. The calculator automatically computes your ISO bargain element and adds it to AMTI.
Review Your Full AMT Breakdown
The results show your AMTI, AMT exemption with phase-out gauge, Tentative Minimum Tax, regular tax comparison, and whether you owe additional AMT. Check the TCJA Sunset Warning for post-2025 planning context, and use the optimization tips if you do owe AMT. Export to CSV or print for your records.
Frequently Asked Questions
What is the AMT exemption for 2025?
For 2025, the AMT exemption is $88,100 for single filers and heads of household, $137,000 for married filing jointly, and $68,500 for married filing separately. These exemptions begin to phase out at $626,350 for single/HOH filers and $1,252,700 for married couples filing jointly, at a rate of 25 cents for every dollar above the threshold. This means the exemption fully disappears at $978,750 for single filers and $1,800,700 for MFJ filers. These are significantly higher than pre-Tax Cuts and Jobs Act amounts and are scheduled to revert to much lower levels after December 31, 2025.
How do ISO stock options trigger AMT?
When you exercise Incentive Stock Options (ISOs), you don't recognize ordinary income for regular tax purposes. However, the bargain element — the difference between the fair market value of the stock on the exercise date and the strike price you paid, multiplied by the number of shares — is treated as an AMT preference item and added to your AMTI. This 'phantom income' can be substantial. For example, exercising 10,000 ISOs with an FMV of $25 and a strike price of $5 creates a $200,000 AMT preference item. If this pushes your AMTI well above the exemption, you could owe tens of thousands in AMT even though you received no cash and may still have unvested shares. The AMT paid on ISO exercises becomes an AMT credit (Form 8801) usable in future years when you sell the shares and recognize regular income.
What is the difference between 26% and 28% AMT rates?
The AMT uses a two-bracket system. For 2025, the first $239,100 of AMT taxable income (after subtracting the AMT exemption) is taxed at 26%, and any AMT taxable income above $239,100 is taxed at 28%. For married filing separately, the 26%/28% threshold is halved to $119,550. An important exception: long-term capital gains and qualified dividends included in AMT taxable income retain their preferential rates of 0%, 15%, or 20% — they are not subject to the 26%/28% AMT rates. This means the effective AMT rate on your total income depends significantly on how much of your income comes from long-term capital gains versus ordinary sources.
What is the AMT credit carryforward and how does it work?
When you pay AMT in a given year due to timing differences — most commonly ISO stock option exercises — that AMT payment generates a Minimum Tax Credit (Form 8801) that carries forward indefinitely. In future years when your regular tax exceeds your AMT (meaning you don't owe any AMT), you can use this credit to reduce your regular tax, effectively getting a refund of the AMT you paid earlier. The key distinction is that only AMT paid on deferral items generates credits — AMT triggered by exclusion items like SALT, standard deductions, or private activity bond interest does not generate future credits. ISO exercises are deferral items because you'll eventually recognize regular income when you sell the shares, at which point the credit becomes available.
Will the TCJA AMT changes expire after 2025?
Yes, unless Congress acts, the favorable AMT parameters enacted by the Tax Cuts and Jobs Act of 2017 are scheduled to expire on December 31, 2025. If the TCJA sunsets, AMT exemptions would revert to approximately $55,400 for single filers and $86,200 for married filing jointly — dramatically lower than the current $88,100 and $137,000. Phase-out thresholds would also revert to much lower levels (approximately $123,000 for single, $164,100 for MFJ), meaning the exemption would effectively be eliminated for most affected taxpayers. This could expose millions of additional taxpayers to AMT, particularly those with large SALT deductions or equity compensation. Planning for this possibility is important if you have significant ISO exercises or other AMT preference items planned for 2026 and beyond.
How can I reduce or avoid AMT?
Several strategies can help minimize AMT liability. For ISO holders, spreading exercises across multiple years keeps the annual AMT preference item smaller and potentially below the exemption threshold — this is the most impactful planning lever. Timing SALT payments is less effective since SALT is fully disallowed under AMT, but understanding this helps with planning. Accelerating ordinary income into a year you already owe AMT can be beneficial since that income may only face 26-28% AMT rates rather than higher regular brackets, effectively lowering your blended rate. Using AMT credit carryforwards from prior years can reduce current AMT liability. Avoiding private activity bond funds if you're already in an AMT position reduces preference items. Finally, if you owe AMT because of ISOs, consider whether a disqualifying disposition (selling shares in the same year) makes sense — you'd owe ordinary income but eliminate the AMT, sometimes resulting in lower total tax.