By Harry Prabandham · Updated September 27, 2026
Equity Compensation
Deciding Whether to Exercise Startup Stock Options
Exercising options converts cash, and often tax, into illiquid company shares; the decision turns on cost, deadlines, tax timing, and money at risk.
Deciding Whether to Exercise Startup Stock Options
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What does exercising a stock option cost?
- Exercising means paying the strike price times the number of shares to turn options into actual shares.
- For NSOs, the spread between the 409A fair market value and the strike is taxed as wage income at exercise.
- For ISOs, there's no regular income tax at exercise, but the spread counts toward the alternative minimum tax.
- Private-company shares usually can't be sold to cover these costs, so both the strike and the tax typically come from savings.
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Full Guide
What does exercising a stock option cost?
- Exercising means paying the strike price times the number of shares to turn options into actual shares.
- For NSOs, the spread between the 409A fair market value and the strike is taxed as wage income at exercise.
- For ISOs, there's no regular income tax at exercise, but the spread counts toward the alternative minimum tax.
- Private-company shares usually can't be sold to cover these costs, so both the strike and the tax typically come from savings.
When is the decision forced?
- Leaving the company starts a post-termination exercise window, commonly 90 days, after which vested options expire.
- ISOs exercised more than three months after employment ends are taxed as NSOs.
- Options also expire at the end of their term, often ten years from grant, and acquisitions can accelerate deadlines.
- Mapping these dates in advance keeps a large decision from being made under a two-week deadline.
How do tax rules reward earlier exercise?
- Exercising when the spread is small keeps tax low, and an 83(b) election within 30 days of an early exercise locks that in.
- ISO shares held more than one year after exercise and two years after grant qualify for long-term capital gains on the full gain.
- Exercise starts the Section 1202 QSBS clock if the company qualifies; shares acquired after July 4, 2025, can exclude 50% of gain after three years, rising to 100% after five.
- For 2026, the AMT exemption is $90,100 single and $140,200 joint, phasing out above $500,000 and $1,000,000 of AMT income.
What is the downside of exercising?
- If the company fails, the strike price is lost and tax already paid is generally not refunded.
- AMT paid on ISOs can create a credit for later years, but recovering it can take a long time.
- Exercised shares tie up cash that may be needed during a job change or emergency.
- Your salary and your shares depend on the same company, so one bad outcome can hit both.
Looking at the company as an outside investor would
- What did the last investors pay, and how much liquidation preference sits ahead of common stock?
- How fast is revenue growing, how long is the runway, and what do recent hiring or layoffs suggest?
- Have there been tender offers or secondary trades, and at what prices?
- Would you buy these shares at this price with money from a brokerage account?
Middle paths between all and nothing
- Exercising part of a grant, such as the lowest-strike shares or ISOs up to the point where AMT begins, limits cash at risk.
- Spreading exercises across tax years can keep each year's AMT or ordinary income lower.
- Company tender offers, permitted secondary sales, and non-recourse exercise financing can fund exercises, each with costs and restrictions.
- Writing down the reasoning and the amount you are willing to lose makes it easier to revisit the decision later.
Key takeaways
- Exercising is an investment decision with a tax bill attached, not just a paperwork step.
- Deadlines, holding periods, and AMT all reward planning before a trigger event.
- Partial and staged exercises can balance tax timing against the risk of losing the money.
- Option taxes depend on your full return; confirm with a CPA, since Rubric does not prepare tax returns and this is general education.
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