Stock option plan guide

Estimates only. This calculator uses simplified assumptions and doesn't account for your complete tax situation or your specific option plan's terms. A tax advisor or equity compensation attorney reviews your actual plan documents. See our full disclaimer.

Stock option exercise calculator

Your option grant

Option type

Total shares granted

% currently vested

Strike / exercise price per share ($)

Current fair market value per share ($, if known) From your most recent 409A valuation, if you have access to it.

Employment status

Your stock option analysis

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A business attorney reviews your specific option plan documents, exercise deadlines, and tax implications, and can advise on strategies like early exercise or 83(b) elections where applicable.

What's the difference between ISOs and NSOs?

Incentive Stock Options (ISOs) receive favorable tax treatment - if holding period requirements are met (generally 2 years from grant and 1 year from exercise), gains are taxed at long-term capital gains rates rather than ordinary income rates. However, ISOs are only available to employees (not contractors or advisors) and have annual value limits.

Non-Qualified Stock Options (NSOs) don't receive this special tax treatment - the difference between the exercise price and fair market value at exercise is generally taxed as ordinary income at exercise, regardless of when shares are eventually sold. NSOs can be granted to employees, contractors, advisors, and board members without the restrictions that apply to ISOs.

If you're building an equity compensation plan for your company rather than evaluating your own options, use the corporate bylaws generator to establish your governance structure first, since equity plans typically require board approval.

What is vesting and why does the "cliff" matter?

Vesting is the schedule by which you earn the right to exercise your options over time, typically as an incentive to stay with the company. A common structure is 4-year vesting with a 1-year cliff - meaning you vest nothing for the first year, then 25% vests at the 1-year mark, with the remainder vesting monthly or quarterly over the following 3 years.

The "cliff" is significant: if you leave before reaching it, you typically forfeit all unvested options entirely, receiving nothing despite having worked at the company. Understanding exactly where you stand relative to your vesting cliff is one of the most important pieces of information when considering a job change.

Why does the post-termination exercise window matter so much?

Most option plans require you to exercise vested options within a specific window after leaving the company - historically often just 90 days, though some companies now offer extended windows (1 year or longer) as a more employee-friendly term. If you don't exercise within this window, you generally forfeit your vested options entirely, even though you earned them through years of work.

This is one of the most consequential and commonly overlooked aspects of leaving a job with unexercised options - the cost to exercise can be substantial, particularly combined with the tax impact, and the decision needs to be made quickly after the window starts, often before you know whether the company will ultimately succeed. Our employment contract generator and business acquisition checklist cover related equity and employment considerations.

Frequently asked questions

An 83(b) election allows you to be taxed on the value of restricted stock (or early-exercised options) at the time of grant/exercise rather than as it vests, which can significantly reduce total tax if the stock's value increases over time. This is most relevant for early exercise of options while the exercise price and fair market value are still close together (typically shortly after a company's founding). The election must be filed with the IRS within 30 days of the grant or early exercise - there are no exceptions to this deadline, and missing it forfeits the potential tax benefit entirely, which is why this decision requires prompt attention rather than being deferred.

Unvested options are typically forfeited entirely upon termination, regardless of the reason for termination, unless your specific plan or employment agreement includes acceleration provisions (common for executives, sometimes negotiated as part of a severance package). Vested options generally remain yours to exercise, subject to the post-termination exercise window described above. If you're being laid off with significant unvested equity close to a vesting milestone, this can sometimes be a point of negotiation in severance discussions, particularly if the timing seems designed to avoid a vesting date.

Exercising ISOs can trigger Alternative Minimum Tax, a separate parallel tax calculation, even though ISO exercise itself isn't subject to regular ordinary income tax. The "bargain element" (difference between fair market value and strike price at exercise) is added back for AMT purposes, which can result in a substantial unexpected tax bill, particularly if you exercise a large number of ISOs when the fair market value has grown significantly above your strike price, especially for a private company where you can't easily sell shares to cover the resulting tax liability. This is a critical and commonly underestimated consideration before a large ISO exercise.

Sometimes, particularly at the time of hiring or during a severance negotiation, though it depends heavily on your use and the company's policies. Some companies have proactively extended their standard post-termination exercise window (to 1, 2, or even 10 years) as a more employee-friendly practice, recognizing how the traditional 90-day window disadvantages long-tenured employees who can't afford the exercise cost and tax bill on short notice. If you're negotiating a job offer with significant equity component, asking about the exercise window policy is a reasonable and increasingly common question.

The strike price is typically set at the fair market value of the company's common stock on the grant date, determined through an independent 409A valuation (required for private companies to avoid adverse tax consequences under IRS rules). As the company grows and its valuation increases, later employee grants typically have a higher strike price than earlier employees, since the underlying stock is worth more. This is why earlier employees at a successful company often have significantly more favorable strike prices relative to current value than employees who joined later.