ISO Exercise AMT Calculator — 2026
Model the alternative minimum tax impact before you exercise ISOs. Uses 2026 federal income tax brackets, AMT exemptions (including OBBBA-adjusted phaseout thresholds), and shows your safe exercise zone — the maximum shares you can exercise this year without triggering additional AMT. Not tax advice; your actual numbers may differ.
How to read these results
Additional AMT owed
This is the extra federal tax you pay in the exercise year — the amount by which the tentative minimum tax exceeds your regular income tax. It is not permanently lost. AMT paid on ISO exercises is a "deferral item" that generates an AMT credit (Form 8801) you can use in future years to reduce regular tax when your regular tax exceeds your AMT.
Safe exercise zone
The maximum ISO shares you can exercise and hold this calendar year without triggering any additional AMT. Many specialist advisors use this as the basis for a multi-year tranche strategy: exercise exactly this many shares each year, converting options to LTCG-eligible shares while staying AMT-neutral. The zone shifts each year with your income and the company's stock price.
Total cash needed
Includes the actual exercise cost (shares × strike price), any AMT owed in the exercise year, and state income tax if your state taxes ISOs at exercise (California and Pennsylvania do; most others don't). You need this cash available before exercising. Some employees use non-recourse exercise financing to cover the gap — see the exercise financing guide.
2026 AMT parameters used in this calculator
| Parameter | Single | Married Filing Jointly |
|---|---|---|
| AMT exemption | $90,1001 | $140,200 |
| Exemption phaseout starts at | $500,000 (OBBBA) | $1,000,000 (OBBBA) |
| Phaseout rate | 50¢ per $1.00 of AMTI above threshold | |
| AMT rate: first $244,500 of AMT base | 26% | |
| AMT rate: above $244,500 | 28% | |
| Standard deduction | $16,100 | $32,200 |
Source: IRS Rev. Proc. 2025-32. Phaseout thresholds reflect OBBBA (One Big Beautiful Bill Act, July 2025) restoration of 2018-level thresholds with 50% phaseout rate (previously 25%, effective since 2018 TCJA).
What this calculator does and doesn't model
- Does model: 2026 federal AMT (exemption, phaseout, 26%/28% rates), 2026 federal regular income tax (graduated brackets), safe exercise zone, AMT credit created, state tax on spread.
- Does not model: State AMT (Colorado, Minnesota, Connecticut have their own); multi-year phased exercise (model each year separately); NIIT on investment income; 83(b) early-exercise on unvested shares (use the 83(b) calculator); NQSO exercises (use the NQSO calculator).
- Regular tax simplification: The calculator uses your W-2 + other ordinary income minus deductions as the tax base, applying 2026 federal brackets. It does not model other credits, AMT preference items beyond the ISO spread, or alternative deductions. Your actual regular tax liability may differ.
Related tools and guides
- 83(b) Election Calculator — early exercise on unvested shares
- NQSO After-Tax Calculator — nonqualified stock option exercises
- RSU Tax Calculator — restricted stock unit vesting tax bill
- ISO AMT Credit Carryforward Guide — how to recover AMT paid in prior years
- AMT and ISO Exercise: Full Guide — mechanics, strategies, and worked examples
- ISO Exercise Timing Framework — tranche strategies and decision windows
- Exercise Financing Guide — funding options when you need exercise capital
Frequently Asked Questions
How is AMT calculated on an ISO exercise?
When you exercise ISOs and hold the shares, the spread (FMV minus strike price) becomes an AMT preference item under IRC § 56(b)(3). Your AMT income (AMTI) equals your regular income plus that spread. AMT is calculated at 26% on the first $244,500 of your AMT base (AMTI minus the AMT exemption) and 28% above that threshold. AMT is owed only when the tentative minimum tax exceeds your regular federal income tax.
What is the 2026 AMT exemption for ISO holders?
For 2026, the federal AMT exemption is $90,100 for single filers and $140,200 for married filing jointly (IRS Rev. Proc. 2025-32). The OBBBA (One Big Beautiful Bill Act, July 2025) restored the phaseout threshold to $500,000 for single filers and $1,000,000 for married filers, where the exemption phases out at 50 cents per dollar of AMTI above the threshold.
What is the ISO safe exercise zone?
The safe exercise zone is the maximum number of ISO shares you can exercise and hold in a calendar year without triggering additional AMT. It depends on your W-2 income, deductions, the per-share spread (FMV minus strike), and filing status. Many specialist advisors use this as the basis for a multi-year tranche strategy — exercising exactly this many shares annually while staying AMT-neutral and starting the LTCG and QSBS holding-period clock.
Can I recover AMT paid on ISO exercises?
Yes. AMT paid on ISO exercises is a "deferral item" under IRC § 53, which creates a recoverable AMT credit tracked on Form 8801. In future years where your regular tax exceeds your tentative minimum tax, you use the credit dollar-for-dollar to offset regular tax. The recovery timeline depends on income variability and your exercise schedule — see the AMT credit carryforward guide for a worked 4-year example.
Do I owe AMT if I exercise ISOs and immediately sell?
No. An immediate same-day sale is a disqualifying disposition — the spread becomes ordinary W-2 income rather than an AMT preference item. You avoid AMT entirely but also forfeit long-term capital gains treatment and any QSBS exclusion eligibility. You owe regular income tax on the full spread instead.
How do I minimize AMT when exercising stock options?
Five common strategies: (1) Exercise only up to your safe zone each year. (2) Spread exercises across multiple tax years to stay below the AMT trigger annually. (3) Exercise ISOs in low-income years — sabbatical, job transition, or after maxing retirement contributions. (4) Coordinate with NQSO exercises, which add to ordinary income but not to AMT income. (5) Consider a disqualifying disposition in a high-liquidity year to restart the credit recovery clock. A specialist advisor models these interactions across your full grant picture.
Get your multi-year plan modeled
A specialist advisor runs your actual grant numbers — multi-year tranche strategy, AMT credit recovery, QSBS stacking — not just this year's exposure. Free match.
Sources
- IRS Rev. Proc. 2025-32 — 2026 tax year inflation adjustments (brackets, AMT exemptions, standard deductions)
- IRS News Release — 2026 adjustments including OBBBA amendments (phaseout thresholds)
- Tax Foundation — 2026 federal income tax brackets
- IRS Topic 556 — Alternative Minimum Tax
Tax values verified June 2026 against IRS Rev. Proc. 2025-32 and Tax Foundation 2026 bracket data.