ISOs vs NSOs 2027 Tax Decision Calculator
Incentive Stock Options (ISOs) and Non-Qualified Stock Options (NSOs) have different tax treatment. ISOs: no regular tax at exercise (AMT may apply), capital gains on sale. NSOs: ordinary income at exercise, capital gains on subsequent appreciation. Source: irs.gov Topic 427.
ISOs vs NSOs — Key Differences
Incentive Stock Options (ISOs): No regular income tax at exercise; bargain spread (FMV - Strike) is AMT preference income. Sale after 2 years from grant + 1 year from exercise: qualified disposition = LTCG on full appreciation. NSOs: Ordinary income tax at exercise on bargain spread. Subsequent appreciation taxed as cap gains (LT or ST). Source: IRS Topic 427.
AMT Trap for ISO Exercises
When exercising ISOs and holding past Dec 31, the bargain spread becomes AMT preference. For a $150,000 spread on 10,000 shares ($20 FMV - $5 strike), AMT taxable amount might force you to pay AMT in the exercise year — sometimes $30-40k surprise. Strategy: cashless exercise + immediate sale (disqualifying disposition) treats as NSO ordinary income, avoiding AMT but losing LTCG opportunity.
Optimal Strategy by Stage
Pre-IPO ISOs: exercise early when FMV ≈ strike (no spread, no AMT) — start LTCG clock + cap gains exposure. Post-IPO ISOs: harder; large spread = AMT trap. Strategy: exercise + immediate sale (disqualifying), or annual partial exercise to stay under AMT crossover. NSOs simpler: exercise when you have liquidity to pay ordinary tax, hold 1 year+ for LTCG.
Disqualifying Disposition for ISOs
Selling ISO shares before holding 2 years from grant AND 1 year from exercise = disqualifying disposition. The bargain spread becomes ordinary income (like NSO) and the AMT credit may help recover prior-year AMT paid. Sometimes intentional to avoid massive AMT liability when stock value uncertain.
Frequently Asked Questions
What's the main difference between ISOs and NSOs?
ISOs: no regular tax at exercise (AMT possible), LTCG on sale if qualified. NSOs: ordinary income tax at exercise on bargain spread. Source: IRS Topic 427.
What triggers AMT on ISO exercise?
Exercising ISOs and holding past Dec 31 — the bargain spread (FMV - Strike) becomes AMT preference income.
How long must I hold ISO shares?
2 years from grant + 1 year from exercise. Both required for qualified disposition (LTCG on full appreciation).
Is exercise + immediate sale taxed as ordinary income?
For ISOs: yes — disqualifying disposition treats spread as ordinary income, like NSO. Eliminates AMT but loses LTCG.
Can I avoid AMT on ISO exercise?
(1) Exercise + sell same year (disqualifying disposition). (2) Time exercise to be 'just below' AMT crossover. (3) Exercise in low-income years.