When you leave a company, your vested stock options stay yours but only briefly: most plans give you around 90 days to exercise them before they expire, and any unvested options are forfeited on your last day. What you actually walk away with depends on three things: how much of your grant had vested, whether you hold Incentive Stock Options (ISOs) or Non-Qualified Stock Options (NSOs), and the reason your employment ended. Miss the exercise deadline and vested options disappear regardless of what they were worth.
Vested and Unvested Options on Your Last Day
Vesting is the line that separates what you keep from what you lose. Vested options are ones you’ve earned the right to buy at the strike price locked in at grant. Unvested options are forfeited the day you leave, with no compensation. Most grant agreements state this directly: vesting stops on your termination date, and anything that hasn’t vested disappears from your account.
Vested doesn’t mean you own shares. You own the right to buy shares at a set price, and that right expires if you don’t use it in time. Treating vested options as money in the bank is a common and expensive mistake.
There is one situation where unvested options can be rescued: acceleration clauses. The most common form is “double-trigger” acceleration, which requires both a change-of-control event like an acquisition and your involuntary termination or a significant role downgrade afterward. “Single-trigger” acceleration vests options on the acquisition alone. If your agreement includes any acceleration language, the definitions of “good reason,” “cause,” and “material change” control the outcome, and those definitions vary from company to company.
The Exercise Window After You Leave
Once you’re gone, a clock starts running on your vested options. Most companies give you about 90 days to decide, gather the cash, and submit the paperwork. This is the post-termination exercise period, and it’s a hard deadline. Miss it by a day and your options expire worthless, reverting to the company’s equity pool.
The 90-day convention comes from federal tax law. Incentive Stock Options must be exercised within three months of leaving to preserve their favorable tax status,1Office of the Law Revision Counsel. 26 USC 422 – Incentive Stock Options so most companies set their exercise window to that limit and apply the same window to NSOs for administrative simplicity, even though NSOs face no such statutory constraint.
Some startups now offer extended exercise windows of a year or longer, recognizing that 90 days forces employees into rushed financial decisions. The specific terms governing your window sit in two documents: the company’s Stock Option Plan and your individual Grant Agreement. Read both before you sign a separation agreement.
How Your Reason for Leaving Changes the Rules
Not every departure is treated the same. The reason you leave can shorten your exercise window, extend it, or wipe it out entirely.
- Voluntary resignation or layoff without cause: you get the standard post-termination exercise period, usually 90 days.
- Termination for cause: many plans let the company cancel all options immediately, including vested ones. If you’re terminated for fraud, theft, or a serious policy violation, you could lose everything regardless of tenure. How your plan defines “cause” controls whether this applies.
- Disability: federal tax law extends the ISO exercise window to one year for disabled employees, and many plans mirror this extension for all option types.1Office of the Law Revision Counsel. 26 USC 422 – Incentive Stock Options
- Death: most plans give an estate or beneficiary an extended period, often up to one year, to exercise vested options.
Definitions for “cause,” “disability,” and “good leaver” vary significantly across plans. If you’re facing termination and hold valuable options, reading those definitions before you sign anything is one of the highest-leverage things you can do.
ISOs vs. NSOs After You Leave
The two main option types follow different rules after departure, and confusing them can cost thousands.
Incentive Stock Options
ISOs get preferential tax treatment only if you follow strict rules. The most important one for a departing employee: you must exercise within three months of your last day for the options to keep ISO status.1Office of the Law Revision Counsel. 26 USC 422 – Incentive Stock Options Exercise after that window and your ISOs automatically convert to Non-Qualified Stock Options, losing their tax advantages.2eCFR. 26 CFR Part 1 – Certain Stock Options
Then there’s the AMT trap. When you exercise ISOs, you don’t owe regular income tax on the spread between your strike price and the stock’s fair market value, but that spread counts as an adjustment for the Alternative Minimum Tax under IRC Section 56. It gets added to your alternative minimum taxable income, which can generate a large and unexpected bill.
An example: strike price of $2, fair market value at exercise of $20. That $18 spread, multiplied across every share you exercise, becomes AMT income. Exercise 10,000 shares and you’ve added $180,000 in AMT income on top of your regular earnings for the year. You haven’t sold anything and you haven’t received a dollar of cash, but you may owe tens of thousands in taxes.
The AMT risk is especially dangerous for departing employees because the 90-day deadline pushes people to act before modeling the tax hit. If you hold ISOs with a large spread and your window is closing, talk to a tax professional first. Exercising in stages across two tax years, or exercising only enough to stay below AMT thresholds, can dramatically reduce the bill.
Non-Qualified Stock Options
NSOs don’t have a statutory three-month deadline tied to their tax status. Your exercise window is whatever the plan says it is, and NSOs don’t convert to anything if you wait. The tradeoff is worse tax treatment from the start: the spread between strike price and fair market value at exercise is taxed as ordinary income, regardless of when you exercise or how long you hold the shares afterward.
Your company must withhold federal income tax and FICA on that spread, and the income appears on your W-2. The withholding rate is the flat supplemental wage rate: 22% federal on amounts up to $1 million, and 37% on amounts above $1 million in the same calendar year.3IRS.gov. Publication 15 – Employer’s Tax Guide Social Security and Medicare taxes apply on top. The practical problem: exercising doesn’t generate cash. You’re buying shares, not selling them, so you need money for both the purchase price and the withholding.
Paying for the Exercise
Exercising means writing a check for the strike price times the number of shares, plus covering the tax withholding. Three main approaches exist, and which are available depends on whether your company is publicly traded.
- Cash exercise: you pay the strike price out of pocket and cover withholding separately. Works anywhere but demands cash on hand.
- Sell-to-cover: you exercise and immediately sell just enough shares to cover the strike price and taxes, keeping the rest. Only works at public companies.
- Cashless exercise: you exercise and sell all the shares at once, pocketing the difference minus taxes and fees. Also requires a liquid market.
If you’re leaving a private company, cash exercise is likely your only route. The shares aren’t publicly traded, so there’s no market to sell into. Departing startup employees often face a hard choice: come up with tens or hundreds of thousands to exercise options on shares they can’t sell, or let them expire. Factor in AMT liability for ISOs and the total out-of-pocket cost can far exceed the strike price alone.
What Happens If the Company Gets Acquired
If the company is acquired while you hold options, whether you’re still employed or already gone with unexercised vested options, the deal terms control the outcome. Acquirers generally do one of three things with outstanding options: cash them out at the difference between the acquisition price and your strike price, convert them into options on the acquiring company’s stock, or cancel them. Underwater options, where the strike price exceeds the acquisition price, are almost always cancelled for nothing.
For unvested options held by current employees, the acquirer may accelerate vesting, assume the grants on a new schedule, or cancel them. Double-trigger acceleration clauses matter most here. If your agreement requires both an acquisition and a subsequent termination or demotion to trigger acceleration, you’re protected if the new owner pushes you out. Without that clause, the acquirer can let unvested options continue on their original schedule and terminate you before they vest.
If you’ve already left and are inside your post-termination exercise window when a deal is announced, move fast. Deals can close quickly, and plan language may allow the company to shorten or cancel your remaining window in connection with the transaction.
Restrictions That Survive Exercise
Exercising options and holding shares doesn’t necessarily put you in the clear. Two categories of restriction can reach you afterward.
Clawback Provisions
Many option agreements contain forfeiture or clawback provisions tied to post-employment conduct. If you go to work for a competitor, solicit former colleagues, or breach confidentiality obligations, the company may have the contractual right to cancel unexercised options or recoup the profit from shares you’ve already exercised and sold.
Courts have generally upheld these provisions, treating them not as illegal non-competes but as a choice: compete or keep your equity gains, but not both. The typical clawback window runs six months to a year after departure, sometimes longer. Look for sections labeled “detrimental activity,” “forfeiture,” or “clawback” in your option agreement or shareholder agreement, and read them before accepting a new job, not after.
Private Company Buyback Rights
At private companies, exercising your options and becoming a shareholder brings another layer of restrictions. Most private companies maintain a Right of First Refusal: you can’t sell your shares to anyone without first offering them to the company at the same price. The company can match any outside offer and keep the shares in-house.
The price at which the company buys back shares is typically based on a 409A valuation, an independent appraisal of the common stock’s fair market value. That figure is usually lower than the company’s headline fundraising valuation because it values common shares rather than the preferred shares investors buy. Even if the company just raised at a $500 million valuation, your shares might be valued at a fraction of that for buyback purposes.
Some agreements go further with mandatory buyback provisions that force departing shareholders to sell their shares back within a set period. If you’re exercising at a private company, understand the repurchase terms before spending the money. You may end up owning shares you can only sell to the company, at a price the company largely controls.
If You Early-Exercised Your Options
Some employers, particularly early-stage startups, allow employees to exercise options before they vest. If you did this and filed an 83(b) election with the IRS within 30 days of exercise, the analysis when you leave looks different. The unvested portion of shares is typically repurchased by the company at your original exercise price, so you get your money back but lose the equity. The vested portion remains yours, and because you already exercised, there’s no post-termination exercise deadline to worry about. You already own those shares, subject to any clawback and buyback rules described above.