Finance term
Stock Option (ISO vs. NSO)
Also known as: ISO, NSO, incentive stock option, non-qualified stock option, NQO
Definition
Stock options give employees the right to buy company shares at a fixed price (exercise/strike price) in the future. ISOs (Incentive Stock Options, IRC Section 422) receive preferential tax treatment — no ordinary income at exercise, potential long-term capital gain. NSOs (Non-Qualified Stock Options, IRC Section 83) are taxed as ordinary income at exercise.
Detailed explanation
Stock options are a right, not an obligation, to purchase shares at a predetermined exercise price. They have value only if the market price (FMV) at exercise exceeds the exercise price — unlike RSUs, which have intrinsic value as long as the stock is worth anything.
## ISO — Incentive Stock Options (IRC Section 422) ISOs may only be granted to employees (not contractors or board members). Under [IRC Section 422](https://www.irs.gov/pub/irs-pdf/p525.pdf), ISOs receive special treatment: no ordinary income tax at exercise (though the spread may trigger AMT); if shares are held 1 year from exercise AND 2 years from grant, the entire gain is long-term capital gain. Annual ISO limit: no more than $100,000 in options (by exercise price × shares) can become exercisable in any calendar year.
## NSO — Non-Qualified Stock Options NSOs can be granted to employees, contractors, board members, or anyone. At exercise, the spread (FMV − exercise price) is ordinary income subject to income and payroll taxes, reported on the W-2 (employees) or Form 1099-NEC (non-employees) per [IRC Section 83](https://www.irs.gov/pub/irs-pdf/p525.pdf). After exercise, the shares' basis equals the exercise price plus the spread taxed as ordinary income. Subsequent appreciation is capital gain.
## Employer Deductibility Employers receive no deduction for ISO exercises. For NSO exercises, employers deduct the spread as compensation when the employee recognizes income. This asymmetry — ISO is better for employees, NSO is better for employers (via deduction) — is why NSOs are common for high-value grants to executives.
◈ Worked example
- ISO exercise: employee granted 10,000 ISOs at $5 exercise price. Exercises when FMV = $25. Spread = $200,000 — no ordinary income tax (but $200,000 AMT preference item). Holds 2 years. Sells at $35. Entire $300,000 gain ($35 − $5 per share × 10,000) taxed at LTCG rate.
- NSO exercise: contractor granted 5,000 NSOs at $3 exercise price. Exercises when FMV = $15. Spread = $60,000 → ordinary income, 1099-NEC from company. Shares have $15 basis. Sells at $20 after 14 months → $25,000 LTCG.
- ISO $100K annual cap: employee granted ISOs for 20,000 shares at $10 exercise price ($200K total). Only $100K worth (10,000 shares) can be classified as ISOs in the first year; the remaining 10,000 shares are automatically NSOs.
Common questions
The most-asked questions about Stock Option (ISO vs. NSO) — answered straightforwardly.
What is the main tax difference between ISO and NSO? +
ISO: no ordinary income tax at exercise (may trigger AMT); sale after qualifying holding period (1 year from exercise, 2 years from grant) produces LTCG. NSO: the spread at exercise is ordinary income — taxed immediately at your marginal rate. Post-exercise appreciation is capital gain. ISOs are more tax-efficient when the stock appreciates significantly and you can hold through the qualifying period.
Should I exercise my ISOs early? +
Early exercise of ISOs (before vesting, under a Section 83(b) election) can start the LTCG holding period earlier and potentially minimize AMT. But it requires paying cash for unvested shares you might forfeit if you leave. The decision involves evaluating the spread, AMT exposure, and your financial situation. Consult a tax advisor with equity compensation experience before exercising significant ISO grants.
Can business owners offer ISOs to contractors? +
No. ISOs are limited to employees under IRC Section 422. Contractors, consultants, and board members can receive NSOs but not ISOs. If a worker's classification changes from contractor to employee, any outstanding options would need to be re-granted as ISOs to qualify for favorable treatment — with a new grant date and potential FMV determination.
Further reading
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