ISO vs NSO at IPO Tax Calculator 2026 β Stock Option Strategy
Calculate ISO AMT exposure vs NSO ordinary income at IPO. Model qualified vs disqualified dispositions, lockup scenarios, 10b5-1 plans, and AMT credit recovery. Multi-scenario post-lockup price analysis.
$
$
$
%
%
Top AMT rate is 28% for amounts over $220,700 (2026) %
ISO Analysis
NSO Analysis
ISO vs NSO at IPO β Key Differences
ISOs offer potential for lower capital gains rates but carry AMT risk. NSOs are taxed as ordinary income at exercise but have no AMT exposure. At IPO, the choice of when and how many options to exercise β and which type β can result in hundreds of thousands of dollars in tax difference.
ISO AMT Adjustment = (IPO Price β Grant Price) Γ Number of ISOs
ISO AMT Tax = AMT Adjustment Γ 28% (minus AMT exemption)
NSO Ordinary Income = (IPO Price β Grant Price) Γ Number of NSOs
NSO Tax at Exercise = Ordinary Income Γ Marginal Rate
Qualified Disposition (ISO): Hold 2yr from grant + 1yr from exercise β LTCG rate
Disqualified Disposition: Spread taxed at ordinary rate in year of sale
AMT Credit: ISO AMT paid carryforward to offset future regular tax (Form 8801)
ISO AMT Tax = AMT Adjustment Γ 28% (minus AMT exemption)
NSO Ordinary Income = (IPO Price β Grant Price) Γ Number of NSOs
NSO Tax at Exercise = Ordinary Income Γ Marginal Rate
Qualified Disposition (ISO): Hold 2yr from grant + 1yr from exercise β LTCG rate
Disqualified Disposition: Spread taxed at ordinary rate in year of sale
AMT Credit: ISO AMT paid carryforward to offset future regular tax (Form 8801)
Example β 50K ISOs, 20K NSOs, $2.50 grant, $25 IPO, $30 post-lockup, 37%/28% AMT:
ISO spread: 50,000 Γ ($25 β $2.50) = $1,125,000 AMT adjustment β $315,000 AMT
NSO income: 20,000 Γ ($25 β $2.50) = $450,000 β $166,500 ordinary tax
If both sold post-lockup at $30 (qualified ISO): gain taxed at LTCG 20%
NSO sale gain: 20,000 Γ ($30 β $25) = $100,000 β $20,000 LTCG tax
ISO spread: 50,000 Γ ($25 β $2.50) = $1,125,000 AMT adjustment β $315,000 AMT
NSO income: 20,000 Γ ($25 β $2.50) = $450,000 β $166,500 ordinary tax
If both sold post-lockup at $30 (qualified ISO): gain taxed at LTCG 20%
NSO sale gain: 20,000 Γ ($30 β $25) = $100,000 β $20,000 LTCG tax
Sources & References (click to expand)
- IRC Β§422 β Incentive Stock Options (ISO qualified disposition requirements)
- IRC Β§83 β Property Transferred in Connection with Performance of Services (NSO taxation)
- IRC Β§55 β Alternative Minimum Tax (AMT) β ISO preference items
- IRS Publication 525 β Taxable and Nontaxable Income (stock options, ISOs, NSOs)
- SEC β Rule 10b5-1 Trading Plans (pre-arranged sale schedules during blackout periods)
Extended
IPO Scenario Planner β Multiple Post-Lockup Prices
Model ISO vs NSO under 5 post-lockup price scenarios. SVG after-tax value chart. AMT credit recovery table.
Model ISO vs NSO performance across 5 post-lockup price scenarios. See after-tax value, AMT credit recovery, and 10b5-1 vs ad-hoc sale comparison.
$
$
%
%
After-Tax Value by Post-Lockup Price Scenario
ISO (Qualified Disp) ISO (Disqualified) NSO After-Tax
5-Scenario Post-Lockup Price Comparison
| Scenario | Post-Lockup Price | ISO Gross Value | ISO Tax (Qualified) | ISO After-Tax | NSO After-Tax | Best Strategy |
|---|
ISO AMT Credit Recovery (Form 8801)
| Year | AMT Credit Available | Estimated Regular Tax | Estimated AMT | Credit Used | Remaining Credit |
|---|
Frequently Asked Questions
What is the AMT risk with ISOs at an IPO?
When you exercise ISOs, the spread (fair market value minus grant price) is NOT regular income β but it IS an AMT preference item. At IPO, if you exercise ISOs on the day of the IPO, the spread (IPO price minus grant price) creates a potentially massive AMT adjustment. If your stock then drops after the lockup expires, you can be left with a massive AMT bill on phantom gains. This is what happened to many tech employees in 2000-2001. The solution: exercise early (while the stock is low), or exercise a calculated number of ISOs to stay within AMT exemption limits.
What is the lockup period and how does it affect options strategy?
IPO lockup agreements prevent insiders (employees, early investors) from selling shares for typically 180 days after the IPO. You cannot sell your exercised shares during this period. This creates risk: if you exercise ISOs at the IPO price and incur a large AMT liability, but the stock drops during the 180-day lockup, you may owe more in taxes than your shares are worth when you can finally sell. Companies sometimes allow a "10b5-1 plan" β a pre-arranged selling schedule that can execute even during blackout periods.
How is a "qualified disposition" of ISOs taxed versus a "disqualified disposition"?
A qualified ISO disposition requires: (1) holding the shares for at least 2 years from the grant date AND (2) at least 1 year from the exercise date. If both conditions are met, the entire gain is taxed as long-term capital gain. A disqualified disposition (selling too early) converts the spread (exercise price to sale price) to ordinary income taxed at your marginal rate. The difference can be enormous: 37% ordinary rate vs 20% LTCG rate on the same gain, plus the AMT credit recovery timeline.
How are NSOs taxed at an IPO?
When you exercise Non-Qualified Stock Options (NSOs), the entire spread (FMV at exercise minus grant price) is ordinary income in the year of exercise β reported on your W-2 and subject to payroll tax withholding. Your company is required to withhold taxes. The cost basis of your shares equals the FMV at exercise. Any subsequent gain when you sell is capital gain β short-term if held less than 1 year, long-term if held more than 1 year. NSOs have no AMT issue, which makes them simpler at IPO but typically results in higher immediate taxes.
What is an AMT credit and how does it help after a disqualifying year?
When you pay AMT in a year due to ISO exercises, you generate a Minimum Tax Credit (Form 8801) equal to the AMT you paid. This credit can be used to reduce your regular tax liability in future years when your regular tax exceeds your AMT (called "coming out of AMT"). The credit carries forward indefinitely. However, in volatile stock markets, you may wait many years to fully recover the credit, and the time value of money reduces its actual benefit. The credit is dollar-for-dollar against future regular tax, not a percentage reduction.