What Is My Employee’s Option Exercise Window After They Leave the Company?

An employee spends years helping build a startup. They vest stock options, contribute to growth, and leave believing they own something valuable.

Then they discover they have only 90 days to exercise their options after leaving the company.

Suddenly, they are facing:

• A potentially large exercise cost
• Possible tax consequences
• Illiquid private shares that cannot be easily sold

Many employees cannot afford to exercise within that timeframe, which means they lose the equity they spent years earning.

This situation happens constantly in startups, and many founders do not fully understand how option exercise windows work until employees begin asking difficult questions during departures.

What is the Option Exercise Window?

The post-termination exercise period, usually called the PTEP, is the amount of time an employee has to exercise vested stock options after leaving the company.

In most startup option plans, the default window is 90 days.

That means once employment ends, the employee generally has three months to:

• Pay the exercise price
• Complete the paperwork
• Handle any tax obligations tied to the exercise

If they do not exercise before the deadline, the vested options typically expire permanently.

Many employees do not realize this deadline exists until they resign or are terminated.

Why the 90-Day Window Creates Problems

The issue is not just the short timeline itself.

The problem is that exercising startup options often requires significant cash at a time when employees no longer receive a salary from the company.

Employees may need to pay:

• The exercise cost itself
• Potential Alternative Minimum Tax (AMT)
• Additional taxes depending on the option structure

At the same time, the company is usually still private, meaning there may be no immediate way to sell the shares and recover liquidity.

That creates a difficult financial decision.

An employee may technically own vested equity but still lack the cash necessary to convert the options into actual shares.

The ISO Tax Issue Makes the Deadline More Important

Many startup employees receive Incentive Stock Options (ISOs), which offer potentially favorable tax treatment under U.S. tax rules.

However, ISOs come with an important condition.

If the employee does not exercise within 90 days after termination, the options automatically lose ISO status and convert into Non-Qualified Stock Options (NQSOs).

That changes the tax treatment significantly.

ISOs can potentially qualify for more favorable capital gains treatment if handled correctly. NQSOs generally trigger ordinary income tax at exercise.

This is one reason the 90-day deadline matters so much. The clock affects not only whether options remain exercisable, but also how they are taxed.

More Companies Are Extending Exercise Windows

In recent years, some startups have started offering longer post-termination exercise windows.

Examples include:

• 5-year windows
• 7-year windows
• 10-year windows in some cases

Companies like Pinterest and Loom publicly became known for extended exercise window policies.

The reasoning is simple: many employees cannot realistically make large financial decisions within 90 days, especially in private companies where liquidity may still be years away.

Extended windows are increasingly viewed as a fairness and retention tool rather than just a compensation detail.

Extended Windows Do Not Preserve ISO Treatment

One common misunderstanding is that a longer exercise window also extends ISO tax advantages.

It does not.

Even if the company allows an employee to exercise years later, the ISO-to-NQSO conversion still occurs after the original 90-day threshold passes.

That means:

• The employee may still exercise later
• But the options will usually be treated as NQSOs for tax purposes

This distinction matters because employees often assume a longer exercise period preserves the original tax structure.

It usually does not.

What Extended Exercise Windows Cost the Company

For founders, extending the PTEP is usually not a direct cash issue.

The larger considerations involve:

• Equity dilution
• Administrative complexity
• Option pool management

Companies may need to amend:

• Option plans
• Individual grant agreements
• Equity policies

Some startups apply extended windows only to employees who meet certain tenure requirements, while others maintain the standard 90-day structure for all grants.

The right approach often depends on:

• Company stage
• Hiring competitiveness
• Retention strategy
• Equity philosophy

Common Founder Mistakes

• Assuming the 90-Day Window Is Legally Required: The 90-day standard is common, but companies can modify exercise windows through plan amendments or customized grant terms.
• Failing to Educate Employees: Many employees sign option agreements without understanding the post-termination deadline or tax implications.
• Assuming Extended Windows Preserve ISO Benefits: Longer exercise periods do not prevent ISO conversion after 90 days.
• Ignoring the Employee Experience: Employees who lose vested equity because they could not afford to exercise often leave with negative perceptions of the company’s equity program.

Why This Conversation Matters Earlier Than Most Founders Think

Employees increasingly evaluate startup offers based not only on equity size, but also on whether the equity is realistically usable.

A large option grant sounds attractive until employees realize they may lose it shortly after leaving.

That is why more candidates now ask questions about:

• Exercise windows
• Liquidity opportunities
• Secondary sales
• Tax treatment

Founders who understand these issues generally build more transparent and trusted equity programs.

10-Minute Founder Self-Check

• Does your option plan clearly define the post-termination exercise window?
• Do employees understand the 90-day deadline before signing grant agreements?
• Have you evaluated whether a longer exercise window makes sense for your company?
• Do departing employees understand ISO-to-NQSO conversion rules?
• Can your plan support extended PTEPs without major amendments?
• Do your equity education materials explain exercise timing and taxes clearly?

If several of these questions are unclear, employees at your company may not fully understand the value of the equity they are earning.

Want to Talk Through How Your Option Plan Handles Employee Departures?

Schedule a free 30-minute call with our team to discuss how we can help you.

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Sources Used

• Carta, “The Post-Termination Exercise Period (PTEP) for Options Explained” — https://carta.com/learn/equity/leaving-company/post-termination-exercise-period/
• WilmerHale, “Commonly Considered Option Program Enhancements: Part III — Granting Options with Extended Post-Termination Exercise Periods” — https://www.wilmerhale.com/en/insights/publications/20230705-option-program-enhancements-part-iii-options-with-extended-post-termination-exercise-periods
• The Startup Law Blog, “When to Exercise Stock Options at a Startup (2026)” — https://www.thestartuplawblog.com/blog/when-to-exercise-stock-options-startup/