How Stock Options Are Reported on W-2 and 1099

Stock options are reported on three different tax forms depending on the type of option and what you did with it. Exercising a non-qualified stock option (NSO) as an employee puts the spread on your W-2; exercising the same option as a contractor puts it on a 1099-NEC; exercising an incentive stock option (ISO) triggers a separate Form 3921 and, if you hold long enough, nothing on your W-2 at all. Selling any of the resulting shares generates a Form 1099-B from your broker, and that form almost always shows the wrong cost basis. Reading each form correctly, and fixing the 1099-B before you file, is the difference between paying tax once and paying it twice on the same dollars.

NSO Exercises on the W-2

When an employee exercises a non-qualified stock option, the spread between the fair market value on the exercise date and the exercise price is compensation income, taxed the same way as a bonus.¹ Your employer folds that spread into several boxes on your W-2:

Box 1 (wages, tips, other compensation): the full spread is added to your salary.
Box 3 (Social Security wages): the spread is included up to the Social Security wage base, which is $184,500 for 2026.²
Box 5 (Medicare wages): the full spread, with no cap.
Box 12, Code V: the spread broken out on its own line.

Code V is the number to protect. It tells you exactly how much of your Box 1 wages came from NSO exercises, and you’ll need that figure when you eventually sell the shares to keep the IRS from taxing the same income again as a capital gain.

Why the Withholding Rarely Covers It

Your employer withholds federal income tax on NSO income at the supplemental wage rate: 22% flat on the first $1 million of supplemental wages in the calendar year, and 37% above that.³ Social Security (6.2%, capped at the wage base) and Medicare (1.45%, uncapped) come out too.

The trap is that 22% often isn’t your real rate. If the exercise pushes your total income into the 32% or 35% bracket, the shortfall lands on your return in April. A quarterly estimated payment in the quarter you exercise is the way to stay ahead of the underpayment penalty.

NSO Exercises When You’re Not an Employee: The 1099-NEC

Independent contractors, outside directors, and other non-employees who exercise NSOs get a Form 1099-NEC instead of a W-2. The company reports the full spread in Box 1 of the 1099-NEC and withholds nothing. Income tax, Social Security, and Medicare all fall to you, which means the spread is also subject to self-employment tax at 15.3%.

One exception forces withholding into the picture: if you never provided a valid taxpayer identification number, or the IRS flagged a TIN mismatch, the company must withhold 24% as backup withholding.³ That 24% is a credit against your final tax, not an extra charge, but you won’t see the cash again until you file.

ISO Exercises: Form 3921, Not the W-2

A qualifying ISO exercise generates no ordinary income and nothing on the W-2. The tax code gives ISOs this treatment as long as you hold the shares more than two years from the grant date and more than one year from the exercise date before selling.⁴

Even though nothing hits your W-2, your employer reports the exercise on Form 3921 and sends you a copy.⁵ The form is informational and it carries two numbers you’ll need later:

Box 3: the exercise price per share.
Box 4: the fair market value on the exercise date.

The gap between them is the bargain element. It’s the figure that drives your Alternative Minimum Tax adjustment for the year of exercise (calculated on Form 6251) and, later, your correct cost basis when you sell. If your employer hasn’t handed you a 3921 by the end of January following the exercise year, ask for it. You cannot fill out Form 6251 correctly without it.

When ISO Income Does Show Up on a W-2

Sell the shares before clearing both holding-period tests and the ISO treatment collapses. The IRS calls this a disqualifying disposition. The ordinary income amount is the lesser of the actual gain on the sale or the bargain element at exercise, and your employer adds it to Box 1 of your W-2 just like NSO income.⁴

This catches people who exercised expecting capital gains treatment, sold early for cash flow reasons, and then found thousands in unexpected compensation income on the W-2 they thought was final.

Selling the Shares: Form 1099-B and the Basis Problem

Every sale of option-acquired stock produces a Form 1099-B from your broker showing gross proceeds and cost basis.⁶ The cost basis on that form is almost always wrong for stock option shares, and that single reporting quirk is where most stock option tax mistakes happen.

For NSO shares, the broker reports only the exercise price as your basis. It does not include the compensation income you already recognized and paid tax on through the W-2. If you copy the broker’s basis onto your return without adjustment, you’ll pay capital gains tax on income that was already taxed as wages.

For ISO shares, the broker also reports only the exercise price. The right basis depends on how the sale plays out. A qualifying disposition uses the exercise price for regular tax and a higher AMT basis (exercise price plus bargain element) for AMT purposes. A disqualifying disposition uses the exercise price plus whatever ordinary income landed on the W-2.

Correcting the Basis on Form 8949

Form 8949 is where you reconcile the broker’s numbers with reality.⁷ Enter the sale as the 1099-B shows it, then use column (f) to enter code B (basis reported to IRS is incorrect) and column (g) for the adjustment.⁸ For an NSO sale, the adjustment is your W-2 Code V amount, entered as a negative number to reduce the reported gain. The corrected totals flow to Schedule D, where short-term versus long-term treatment gets settled. Long-term rates require holding the shares more than one year past the exercise date.⁹

If a Form Is Missing or Wrong

You cannot file a clean return without the right forms in hand. A missing 3921 blocks your AMT calculation for an ISO exercise. A W-2 without a Code V entry, or with the wrong Code V amount, will either understate your wages or leave you with no clear number to plug into Form 8949 when you sell. A 1099-NEC missing after a contractor exercise is a hint that self-employment tax and estimated payments were probably neglected too.

Ask the employer or issuer to correct the form. If they don’t, file with the numbers you can support from your own records (exercise confirmations, brokerage statements, grant agreements) and keep documentation of what you asked for and when. The IRS treats the W-2 and 1099 series as the authoritative record, so an incorrect form left uncorrected tends to surface later as a notice, not a quiet win.

1
Internal Revenue Service. Topic No. 427, Stock Options
2
Social Security Administration. 2026 Cost-of-Living Adjustment (COLA) Fact Sheet
3
Internal Revenue Service. Publication 15 (2026), (Circular E), Employer’s Tax Guide
4
Office of the Law Revision Counsel. 26 USC 422 – Incentive Stock Options
5
Internal Revenue Service. About Form 3921, Exercise of an Incentive Stock Option Under Section 422(b)
6
Internal Revenue Service. About Form 1099-B, Proceeds from Broker and Barter Exchange Transactions
7
Internal Revenue Service. About Form 8949, Sales and Other Dispositions of Capital Assets
8
Internal Revenue Service. 2025 Instructions for Form 8949
9
Internal Revenue Service. Topic No. 409, Capital Gains and Losses