Should you exercise your stock options before leaving a job?

When you leave a startup, the clock starts: your plan controls when vested options expire, while ISO tax status generally requires exercise within three months after employment ends. Exercising can still mean writing a real check for shares and taxes.

This decision is hitting a lot of people right now. By mid-August 2026, tech layoffs had already passed the full-year 2025 total, which means a wave of employees are staring at a separation agreement, an exercise window, and a roughly three-month ISO-status period they may not fully understand. If that’s you, here’s how to think it through before the window closes.

The 3-month ISO-status rule

Federal tax law generally provides a three-month period after employment ends to exercise and retain ISO status. Your plan—not the IRS—controls the option’s actual expiration. If the plan permits a later exercise, that exercise is taxed as an NSO; passing three months does not itself forfeit the option. The ISO-status period is one year for disability, and the three-month employment rule does not apply after death.

Some companies offer extended windows — three, five, even ten years. If you exercise after the statutory ISO-status period, the exercise is taxed as an NSO, provided the option remains exercisable under the plan. Read your separation agreement for the exact deadline and whether any extension applies.

What it actually costs to exercise

Exercising isn’t a button you click. It’s a purchase. The cost has two parts.

Part one: the shares. You pay the strike price times the number of options you’re exercising, in cash, out of pocket. At a private company you generally can’t sell some of the shares to cover the rest (a “cashless exercise”). There’s no market to sell into. So you need the actual cash.

Part two: the tax. This is the part that surprises people, because you can owe tax without receiving a dollar.

• For ISOs, the spread between the fair market value and your strike price at exercise is an “adjustment” for the Alternative Minimum Tax. Exercise and hold through year-end, and that spread can push you into AMT: a tax bill on paper gains, with no cash in hand. This is the classic “AMT trap.”
• For NSOs, the spread is taxed as ordinary income at exercise. There is no separate ISO AMT preference adjustment.

The AMT math depends on the 2026 thresholds. Per the IRS, the AMT exemption for 2026 is $90,100 for single filers and $140,200 for married couples filing jointly, phasing out at $500,000 and $1,000,000 respectively. Under the One Big Beautiful Bill Act, that phaseout is now steeper: you lose 50 cents of exemption per dollar over the threshold. Whether you actually owe AMT, and how much, comes down to the size of your spread against those numbers.

Rather than estimate it in your head, run your own numbers through the ISO exercise tax calculator. It takes your strike, share count, and current valuation and shows the exercise cost and the AMT exposure.

The four questions that actually decide it

Strip away the mechanics and the decision comes down to four honest questions.

Can you afford it? Add the strike-price cost and the estimated tax bill. That’s the real number. If exercising drains your emergency fund right after you’ve lost your income, that alone may answer the question.

Do you believe in the company? Exercising is buying stock in a private company you’re leaving. If you wouldn’t invest that same cash in it as an outside investor today, that’s worth sitting with.

How far away is a liquidity event? Your cash is locked up until the company sells, goes public, or runs a tender offer. That could be years. Could be never.

Can you afford to lose it entirely? This is the one people skip. If you exercise and the company fails, the cash you spent — on shares and on taxes — is gone. Exercising is a bet, and the stake is real money you’re spending on the way out the door.

The ISO-to-NSO tax-treatment cutoff

If you decide the options are worth keeping but exercise after the roughly three-month ISO-status period, you don’t necessarily lose them, provided the plan still allows exercise, but the exercise is generally taxed as an NSO. Held properly as ISOs (exercised within the statutory period and held long enough after), your eventual gain can qualify for long-term capital gains rates. With NSO tax treatment, the spread at exercise becomes ordinary income instead. On a large spread, that difference can run into six figures of extra federal tax.

So you need to track both the plan’s exercise window and the roughly three-month ISO-status period. For valuable grants, the choice may be “exercise in time to retain ISO treatment, or accept NSO tax treatment later if the plan still allows exercise.” That’s a reason not to let either deadline pass by default.

What to do next

If you’ve just left or been laid off, the sequence is: find your exact exercise deadline in your paperwork, count the vested shares, and calculate the full cost — strike plus tax — before you decide anything. Don’t let the exercise window run out simply because the math felt overwhelming. And if the numbers are large, this is worth an hour with a tax professional who does equity — the cost of good advice is trivial against the cost of getting AMT wrong.

Start with the numbers. The ISO exercise tax calculator will tell you what exercising would actually cost you, so you’re deciding with facts instead of dread. For the bigger picture on how AMT is hitting option holders this year, see our piece on why AMT risk is rising for ISO holders in 2026.

Frequently asked questions

How long do I have to exercise stock options after leaving?

Your plan sets the actual exercise deadline. Federal law generally gives you a three-month period after employment ends to exercise and retain ISO tax treatment. If the plan allows you to exercise after that period, the exercise is generally taxed as an NSO; extending the exercise window does not itself change the option’s ISO status during the statutory period. The ISO-status period is one year after employment ends due to disability, and different rules apply after death. Check your specific plan and separation agreement.

What does it cost to exercise stock options?

The strike price times the number of options, paid in cash, plus potential tax. For ISOs, exercising can trigger Alternative Minimum Tax on the spread between fair market value and your strike, even though you haven’t sold anything. For NSOs, the spread is taxed as ordinary income at exercise.

Should I exercise my options if I’m getting laid off?

Only if you can afford the full cost (shares plus tax), you believe in the company’s future, and you can afford to lose that money if it fails. The cash is locked up until a liquidity event that may be years away or may never come. Run your numbers before deciding.

What happens if I don’t exercise within three months?

Check the plan. If the option remains exercisable, a later exercise is taxed as an NSO; if the contractual term has expired, it cannot be exercised. Disability and death have different statutory rules. Consult your own tax advisor about your circumstances.