A non-qualified stock option, or NSO, is a contractual right to buy a set number of your company’s shares at a fixed price, and when you exercise, the difference between that price and the current market value is taxed as ordinary income at federal rates that reach 37% in 2026.1Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 The IRS calls them “nonstatutory stock options” to distinguish them from incentive stock options (ISOs), which follow different rules.2Internal Revenue Service. Topic No. 427, Stock Options Companies use NSOs to compensate employees, consultants, board members, and independent contractors, which makes them the most flexible form of equity pay in common use.
The Basic Mechanics: Grant, Vesting, Expiration
On the grant date, your company’s board approves the option and sets a strike price, which is the amount you’ll pay per share whenever you decide to exercise. The strike price is almost always set at the stock’s fair market value on the grant date.
You can’t exercise immediately. Options come with a vesting schedule that requires continued service. A common arrangement is four years with a one-year cliff: nothing vests until your first anniversary, then options vest monthly or quarterly over the remaining three years. Your specific schedule is spelled out in the option agreement.
NSOs also carry an expiration date, typically ten years from grant. If you never exercise before that deadline, the options vanish. That gives you a real planning window in which to weigh price, taxes, and personal cash flow.
What You Owe When You Exercise
Receiving the grant itself is not a taxable event. The tax hits when you exercise.2Internal Revenue Service. Topic No. 427, Stock Options At exercise, the difference between the current market price and your strike price, called the spread, counts as ordinary income for the year. If your strike price is $10 and the stock trades at $50 the day you exercise, that $40 per share is taxable income whether you sell the shares or hold them.
For employees, this income appears on your W-2 alongside regular wages. For consultants and outside board members, it appears on a 1099. Either way, the spread is subject to the full stack of income and payroll taxes:
- Federal income tax at rates from 10% to 37% in 2026, with the top bracket beginning above $640,600 for single filers.1Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026
- Social Security tax of 6.2% on earnings up to $184,500 in 2026. If your regular salary already exceeds the cap, the exercise won’t add more Social Security tax.3Social Security Administration. Contribution and Benefit Base
- Medicare tax of 1.45% with no earnings cap.
- Additional Medicare Tax of 0.9% once your combined wages and exercise income cross $200,000 (single) or $250,000 (married filing jointly). Your employer does not match this portion.4Internal Revenue Service. Topic No. 560, Additional Medicare Tax
Why Withholding Often Falls Short
Your employer withholds on the exercise spread the way it would on a bonus, because the IRS treats both as supplemental wages. The default federal withholding rate is a flat 22%. If your total supplemental wages for the year exceed $1 million, the excess is withheld at 37%.5Internal Revenue Service. Publication 15, Employer’s Tax Guide
That flat 22% is the trap. If your actual marginal rate is 32% or 35%, withholding won’t cover the bill, and you’ll owe a substantial balance when you file. State supplemental withholding rates vary and add another layer. Setting aside an additional 10% to 20% of the spread before filing is a practical hedge.
When Not to Exercise
If the stock price sits below your strike price, your options are underwater. The spread is zero and doesn’t produce a loss. Exercising would mean paying more per share than the open market charges, so there’s no reason to do it. Wait, and hope the price recovers before the option expires.
What You Owe When You Sell the Shares
A second layer of tax applies to any gain after you exercise. Your cost basis in the shares is the fair market value on the exercise date, not the strike price you paid. Any gain above that basis is a capital gain, and the rate depends on how long you hold the shares after exercising.
Shares sold within a year of exercise are taxed at short-term capital gains rates, which match ordinary income brackets. Shares held longer than a year qualify for long-term rates of 0%, 15%, or 20%. For single filers in 2026, the 0% rate applies to taxable income up to $49,450, the 15% rate covers $49,450 to $545,500, and the 20% rate applies above that.6Internal Revenue Service. Topic No. 409, Capital Gains and Losses
High earners face an additional 3.8% Net Investment Income Tax on capital gains once modified adjusted gross income exceeds $200,000 (single) or $250,000 (married filing jointly). Those thresholds are not indexed for inflation.7Internal Revenue Service. Questions and Answers on the Net Investment Income Tax The exercise income itself isn’t investment income, but it does inflate your AGI, which can pull other investment gains over the threshold.
Sales get reported on Schedule D of Form 1040, with transaction detail on Form 8949.8Internal Revenue Service. About Schedule D (Form 1040), Capital Gains and Losses
The Cost Basis Trap That Causes Double Taxation
This is the mistake that costs NSO holders the most money. When your broker issues a 1099-B for the sale, the cost basis often reflects only the strike price you paid, not the higher fair market value on the exercise date. Take that number at face value and you’ll pay capital gains tax on the same income you already paid ordinary income tax on at exercise.
The fix is on Form 8949. Enter the basis your broker reported in column (e), then enter an adjustment in column (g) using code “B” to increase the basis to the fair market value on the exercise date.9Internal Revenue Service. Instructions for Form 8949, Sales and Other Dispositions of Capital Assets Skipping this step is writing the IRS a check you don’t owe.
How to Actually Exercise
Most companies run exercises through an equity management platform where you initiate the transaction online. Where no platform exists, you submit a written notice of exercise to the corporate secretary specifying how many shares you want. You’ll typically pick from three payment methods.
A cash exercise means you pay the full strike price and tax withholding out of pocket and keep every share. You get maximum upside, but you need serious liquidity. A cashless exercise, also called a same-day sale, has the broker sell all the shares immediately, deduct the strike price and taxes from the proceeds, and hand you the cash. You end up with money, not equity. A sell-to-cover sits in the middle: the broker sells just enough shares to cover the strike price and withholding and deposits the rest in your brokerage account.
The right method turns on your cash position and your view of the stock. Cash exercise fits when you have the liquidity and expect the price to keep climbing. Sell-to-cover is the pragmatic default when you want to keep shares without a large outlay. Cashless is the cleanest exit when you’d rather have cash than a concentrated position.
Early Exercise and the 83(b) Election
Some plans, particularly at early-stage startups, let you exercise options before they vest. You receive restricted shares that remain subject to the original vesting schedule, and the company keeps the right to buy back unvested shares at the strike price if you leave.
Filing an 83(b) election with the IRS within 30 days of the early exercise tells the government to tax you now on the current spread rather than later as each tranche vests. At a startup where the stock is still worth pennies, that spread might be zero, so the tax cost of the election can be nothing. Future appreciation can then qualify for long-term capital gains rates if you hold the shares long enough.
The risks are real. Leave before vesting and you forfeit the unvested shares, with no refund of tax already paid. If the company fails, you’ve paid tax on value that evaporated. And the 30-day filing deadline is absolute; the IRS grants no extensions, and a late filing is the same as no filing.
What Happens When You Leave
Unvested options are almost always forfeited immediately when you leave. Vested options usually come with a post-termination exercise window of 90 days from your last day. After that window closes, unexercised options expire worthless. Some employers offer six months or a year, but 90 days is the industry default.
Exercising inside that window means producing the strike price and tax withholding on short notice. On a large vested block, that can mean writing a check for tens of thousands of dollars during a stretch when no paycheck is arriving. Run the numbers on cash exercise versus sell-to-cover before you give notice, not after.
Even if you stay for decades, every option has a maximum term. Options that reach expiration unexercised disappear, however valuable they might be.
NSOs vs. Incentive Stock Options
Many employees hold both types, and the two should not be planned the same way. NSO spreads are taxed as ordinary income at exercise. ISO exercises trigger no regular income tax, but the spread is a preference item for the Alternative Minimum Tax and can generate a large AMT bill on its own. NSOs can be granted to employees, consultants, contractors, and board members; ISOs are limited to employees. NSOs have no annual limit; ISOs have a $100,000 annual vesting cap based on grant-date fair market value, and any excess is automatically treated as an NSO. NSO plans can allow transfers to family members or trusts; ISOs can only pass at death. NSO terms can extend beyond ten years; ISOs must expire within ten years of grant.