How to exercise stock options: step-by-step guide with examples
The steps from a vested grant to shares on the cap table — the documents to read first, the ways to pay, the tax to model, and the deadlines that cannot be missed.
The short answer
To exercise stock options, including ISOs, you read your grant to confirm what has vested and when it expires, price the spread at the latest 409A value, model the tax, choose how to pay, then submit an exercise notice with payment — and file any 83(b) election within 30 days. The cash you need is the strike price times the shares, plus any tax on the spread: shares × strike + tax on shares × (fair market value − strike). At a private company there is usually no market to sell into, so both parts come out of your own pocket — and the deadlines, unlike the price, do not move.
What does “exercise my stock options” mean, and what happens when I do?
An option is the right to buy company shares at a fixed strike price. Exercising it means using that right: you pay the strike, and the company issues you the shares. Until then you own nothing but the contract — no vote, no dividends, and nothing that survives the option’s expiry. What happens when you exercise your stock options is that four things change at once. You become a shareholder of record on the company’s cap table. Your money is now at risk in the shares, not just your time. A tax event may occur, depending on the option type.
How to exercise stock options, step by step
Read the grant and the plan Find the option type (ISO or NSO), the strike, the number vested, the expiry date, the window after leaving, whether early exercise is allowed and what transfer restrictions apply to the shares. Check the deadlines Options expire — ISOs no later than ten years after grant. If you are leaving, find the post-termination window; many plans use 90 days, and ISOs lose their status after three months. Price the spread Ask the company for the current fair market value — at a private company, the latest 409A valuation.
How to exercise ISO stock options
The steps are the same; what changes is what to watch. Exercising an incentive stock option creates no wages, no withholding and no payroll tax. The spread instead goes onto the AMT calculation for the year, and if the result exceeds your regular tax, the difference is due in April — whether or not you could sell the shares. The company reports the exercise on Form 3921, as IRS Topic 427 notes. Three ISO rules shape the timing. Exercise within three months of leaving, or the options are taxed as NSOs.
How to exercise stock options of a private company
Three things differ from a listed company. The price is an appraisal, not a quote: the fair market value used for the spread is the board’s latest 409A, usually below the price of the last preferred round. The shares cannot simply be sold: transfers usually need the company’s consent and are subject to a right of first refusal, so there is rarely a same-day sale to pay for the exercise. And liquidity arrives on the company’s schedule — a tender offer, an acquisition or an IPO — not yours. That makes exercising at a private company an investment decision with a tax bill attached.
How to exercise stock options without cash
A truly cashless exercise — the broker sells enough shares the same day to cover the strike and the tax — needs a market, so it is mostly available after a listing. Before one, the routes are narrower, and each carries a risk worth naming. Same-day sale (listed company) For ISOs, shares sold in the year of exercise are a disqualifying disposition: the spread is ordinary income. Decide that on purpose. Exercise in a tender offer Some company-run tenders let you exercise and sell in one step. The price and the amount you may sell are set by the company.
Worked example: the cash one exercise needs
A single employee earns $216,100 in salary in 2026, with $200,000 of taxable income, and holds 8,000 options with a $3 strike. Exercising costs $24,000 in every case; the tax depends on when and on the option type. The same 8,000 options cost $24,000 or more than twice that, depending only on timing and type. The early exercise is cheapest in tax and riskiest in capital: the $24,000 is committed before anyone knows whether the company will be worth more than $3 a share.
Checklist before you exercise vested stock options
Option type confirmed in the grant agreement, including any part above the $100,000 ISO limit Expiry date and post-termination window written down Latest 409A value obtained in writing, with its date Whole-year tax model run, including AMT for ISOs and the withholding gap for NSOs Cash for strike and tax set aside, with no reliance on a sale before April Transfer restrictions and right of first refusal read 83(b) election drafted in advance if the shares are unvested Records folder ready for the confirmation, Form 3921 or W-2
Common errors when exercising stock options
Letting options expire Unexercised options lapse at the end of the term or the post-termination window, and the value goes with them. Exercising after a new 409A A higher appraisal raises the spread and the tax for the same shares. Ask when the next one is due. Exercising ISOs in December without a model The spread joins the whole year’s AMT calculation. A model run after the trade cannot change it. Filing the 83(b) on day 31 The deadline has no extension. A late election leaves tax measured at each vesting date.
When to get professional tax or legal advice
The ISO spread is large A tax adviser should run AMT on your whole return before you exercise. You are leaving the company The window is short; get the tax model and the plan reading done in the first weeks. You are offered early exercise or an 83(b) Have an adviser check the election and the 30-day timing. You are considering exercise financing Have a lawyer read the contract, especially what happens if the company never exits. You moved state or country during vesting More than one tax authority may claim part of the income.
The terms this page uses
Exercise Paying the strike price to turn options into shares the company issues to you. Strike price The fixed price per share in the grant, normally the 409A value on the grant date. Spread Fair market value at exercise minus the strike, times the shares — the amount that is taxed. Early exercise Exercising options before they vest, where the plan allows it, receiving shares the company can buy back if you leave. 83(b) election A filing within 30 days of receiving unvested shares that fixes the tax measurement at that date.
Questions about exercising stock options
How do you exercise share options at a private company? Through the company: you sign an exercise notice, usually on its equity platform, pay the strike and any withholding, and the company issues the shares. There is no broker and usually no market, so you need the cash yourself. Should I exercise options before they vest? Only if the plan allows early exercise and you can afford to lose the money. It can cut the tax sharply when the spread is near zero, provided you file the 83(b) election within 30 days. Do I pay tax when I exercise ISOs? Not regular income tax, and no payroll tax.
How do you exercise share options at a private company?
Through the company: you sign an exercise notice, usually on its equity platform, pay the strike and any withholding, and the company issues the shares. There is no broker and usually no market, so you need the cash yourself.
Should I exercise options before they vest?
Only if the plan allows early exercise and you can afford to lose the money. It can cut the tax sharply when the spread is near zero, provided you file the 83(b) election within 30 days.
Do I pay tax when I exercise ISOs?
Not regular income tax, and no payroll tax. The spread counts for the alternative minimum tax, which may or may not produce a bill depending on its size and the rest of your return.
What happens to my options if I leave the company?
Unvested options usually lapse. Vested options must be exercised within the plan’s post-termination window or they expire; ISOs exercised more than three months after leaving are taxed as NSOs.
Can I exercise only part of my vested options?
Most plans allow partial exercise, often with a minimum number of shares. Spreading exercises over several tax years is a common way to manage AMT on ISOs.
Where every rule on this page comes from
Every rule, rate and deadline was checked against the US Code and the IRS on 1 October 2026 and applies to tax year 2026. Plan terms such as post-termination windows and early exercise vary by company and are described as such. The worked example is illustrative arithmetic, not market data.