Stock Options Tax Calculator (ISO vs NSO)
Calculate tax on ISO and NSO stock options at exercise and sale. Compare ISO vs NSO tax treatment.
Spread Per Share
$40.00
Total Spread
$40,000.00
Net After-Tax Value
$34,000.00
Tax Breakdown
| Gross Value | $50,000.00 |
| Total Cost (exercise) | $10,000.00 |
| Total Spread | $40,000.00 |
| AMT at Exercise (28%) | $11,200.00 |
| LTCG Tax at Sale (15%) | $6,000.00 |
| Net After-Tax Value | $34,000.00 |
Use the Stock Options Tax Calculator (ISO vs NSO) above to calculate your results. Enter your values and see instant results — all calculations run in your browser.
Disclaimer: This calculator is for informational purposes only and does not constitute tax, financial, or legal advice. Results are estimates based on the information you provide and current rates. Always consult a qualified tax professional or financial advisor for advice specific to your situation.
How It Works
This calculator compares the tax implications of Incentive Stock Options (ISOs) versus Non-Qualified Stock Options (NSOs) to help employees make informed decisions about stock compensation. Understanding these differences is crucial since ISOs receive preferential tax treatment but come with restrictions, while NSOs are taxed as ordinary income upon exercise.
The calculator determines regular income tax, Alternative Minimum Tax (AMT), and capital gains obligations for each option type. For ISOs, the spread at exercise may trigger AMT but isn't subject to regular income tax until sale, while NSOs create immediate ordinary income tax liability on the spread between exercise price and fair market value.
A common mistake is exercising ISOs late in the year without considering AMT implications, which can create unexpected tax bills. Remember that ISO benefits are lost if shares are sold within two years of grant or one year of exercise (disqualifying disposition), and AMT paid on ISO exercise may be recoverable as a credit in future years.
Employee with 1,000 ISOs at $10 strike price, current value $50
- 1 Calculate the spread: 1,000 shares × ($50 current price - $10 exercise price) = $40,000 total spread
- 2 For ISOs: $40,000 spread triggers AMT calculation but no regular income tax. For NSOs: $40,000 is taxed as ordinary income at marginal rate (assume 32% = $12,800)
- 3 ISO AMT impact: $40,000 × 28% AMT rate = $11,200 potential AMT (subject to exemption). NSO also incurs payroll taxes: $40,000 × 7.65% = $3,060 additional
- 4 Total immediate tax cost: ISOs potentially $11,200 (AMT only), NSOs $15,860 ($12,800 income + $3,060 payroll taxes). ISOs provide $4,660 immediate savings but require holding shares for preferential treatment
Source: IRS — Forms, Instructions & Publications · Last updated: April 2026
Frequently Asked Questions
How are stock options taxed?
What is the difference between ISO and NSO tax treatment?
Do I owe AMT on incentive stock options?
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