Stock option payout tax rates fall into two very different ranges depending on the type of option you hold and how long you keep the shares. Nonstatutory stock options (NSOs) produce ordinary income at exercise, taxed at federal rates from 10% to 37% plus Social Security and Medicare. Incentive stock options (ISOs) can qualify for long-term capital gains rates of 0%, 15%, or 20% if you meet two holding periods, though the spread at exercise may pull you into the Alternative Minimum Tax. On the same underlying gain, the gap between the two paths often runs into tens of thousands of dollars.
How NSO Payouts Are Taxed
The taxable event for an NSO is the exercise, not the vest and not the eventual sale. The IRS treats the spread between the stock’s fair market value on the exercise date and the strike price you paid as compensation income, in the same category as your salary.1Internal Revenue Service. Topic No. 427, Stock Options Federal income tax, Social Security tax (6.2%), and Medicare tax (1.45%) all apply to that spread whether you sell the shares or keep them.
Your employer withholds federal income tax on NSO income at the supplemental wage rate: a flat 22% on amounts under $1 million and 37% on anything above $1 million in the same calendar year.2Internal Revenue Service. Publication 15 – Employer’s Tax Guide That 22% often undershoots your actual rate. A large exercise can lift your total income into the 32%, 35%, or 37% bracket, and the difference between what was withheld and what you owe lands as a bill in April.
The Social Security portion applies only to earnings up to $184,500 in 2026.3Social Security Administration. Contribution and Benefit Base If your salary already exceeds that cap, the spread owes no additional Social Security tax. Medicare tax has no cap.
After exercise, further movement in the stock is a separate capital gains event. Hold the shares more than one year after exercise and additional appreciation qualifies for long-term capital gains rates. Sell within a year and the extra gain is short-term, taxed at ordinary rates.
How ISO Payouts Are Taxed
ISOs run on a different clock. No ordinary income tax applies at grant, vesting, or exercise.1Internal Revenue Service. Topic No. 427, Stock Options The rate you eventually pay depends on whether you satisfy both holding periods in Section 422 of the Internal Revenue Code:
- At least one year from the exercise date, and
- At least two years from the original grant date.
Clear both and the entire gain from strike price to sale price is taxed at long-term capital gains rates.4Office of the Law Revision Counsel. 26 U.S. Code 422 – Incentive Stock Options No payroll taxes apply. That is the core advantage of an ISO over an NSO.
Sell before satisfying either period and you have a disqualifying disposition. The spread between the strike price and the fair market value on the exercise date converts to ordinary income, appears on your W-2, and is taxed at your regular rate. Any additional gain above the exercise-date value is a capital gain, short-term or long-term depending on your holding period.1Internal Revenue Service. Topic No. 427, Stock Options The two-year-from-grant rule is where people most often slip, because they focus only on the one-year post-exercise clock.
The Actual Rate Tables
Whether your payout falls under ordinary rates or capital gains rates changes the tax by more than half.
Ordinary Income Rates
NSO exercise spreads, ISO disqualifying dispositions, and short-term capital gains all run through the ordinary brackets. For 2026, a single filer’s federal rates start at 10% on the first $11,925 and rise to 37% on income above $626,351.5Internal Revenue Service. Federal Income Tax Rates and Brackets A single large exercise can move you into a bracket you have never occupied before, so the marginal rate on the option income is usually higher than the rate you pay on your salary alone.
Long-Term Capital Gains Rates
Qualifying ISO sales, and NSO shares held more than a year after exercise, are taxed at 0%, 15%, or 20% depending on taxable income.6Internal Revenue Service. Topic No. 409, Capital Gains and Losses For 2026, the 20% rate begins around $545,500 for single filers and $613,700 for joint filers. Most option holders land in the 15% band. The gap between paying 37% and paying 15% on the same dollar is the whole reason ISO holding periods matter.
Net Investment Income Tax
High earners pay an additional 3.8% surtax on net investment income, capital gains from stock sales included. It applies to the lesser of your net investment income or the amount by which your modified adjusted gross income exceeds $200,000 (single) or $250,000 (married filing jointly).7Office of the Law Revision Counsel. 26 U.S. Code 1411 – Imposition of Tax Those thresholds are set by statute and do not adjust for inflation, so they catch more filers each year. A large sale can push you well past them even if your salary alone would not.
The AMT Trap on ISO Exercises
The ISO advantage comes with a catch. You owe no ordinary tax at exercise, but the strike-to-market spread counts as an adjustment for the Alternative Minimum Tax. The AMT is a parallel calculation that adds back certain items to ensure a floor level of tax.
If you exercise ISOs and hold the shares past the end of the calendar year, the spread flows into your alternative minimum taxable income. For 2026, the AMT exemption is $90,100 for single filers and $140,200 for joint filers.8Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 Combined with your other income, an ISO spread that lifts you over the exemption can trigger AMT at 26% or 28% on the excess. The calculation happens on Form 6251, with the ISO adjustment reported on Line 2i.9Internal Revenue Service. Instructions for Form 6251
A same-year sale removes the problem. If you sell the shares before December 31 of the exercise year, the disposition converts the income to ordinary compensation and the ISO adjustment falls away. Some holders deliberately arrange a disqualifying disposition late in the year when the AMT hit would be worse than paying ordinary rates on the spread.
Recovering AMT in Later Years
AMT paid because of an ISO exercise creates a minimum tax credit that carries forward with no expiration. In any later year where your regular tax exceeds your tentative minimum tax, the difference can be claimed as a credit on Form 8801. The credit rarely comes back in a single year, but filing Form 8801 annually draws it down. This is real money that many ISO holders leave on the table because they never file the form after the exercise year.
What a Payout Actually Looks Like
Take 1,000 options at a $10 strike, with the stock at $50 on the exercise date. The spread is $40 per share, $40,000 total. From there the three main outcomes split:
- NSO exercise: the $40,000 is added to your W-2. Your employer withholds 22% federal ($8,800), plus Social Security (subject to the cap) and Medicare. If you later sell at $70, the extra $20 per share is a separate capital gain, long-term if you held over a year.
- ISO qualifying disposition: nothing hits your W-2. The $40,000 enters the AMT calculation but is not ordinary income. When you sell at $70 after meeting both holding periods, the full $60 per share ($60,000) is taxed at long-term capital gains rates.
- ISO disqualifying disposition: the $40,000 spread lands on your W-2 as ordinary income, and the remaining $20,000 is a capital gain.
The 22% flat NSO withholding on $40,000 produces $8,800 in federal tax collected. If the exercise pushes you into the 32% or 35% bracket, the shortfall is yours to cover at filing.2Internal Revenue Service. Publication 15 – Employer’s Tax Guide
The Cost Basis Mistake That Doubles Your Tax
This is where option holders most often overpay, and it is entirely avoidable. When you exercise NSOs, or make a disqualifying disposition of ISOs, the spread is already reported as ordinary income on your W-2. When you later sell, your broker issues a Form 1099-B that frequently shows only the strike price as your cost basis, not the higher amount that already includes the income you were taxed on.
Report the sale using just the 1099-B figure and you pay capital gains tax a second time on income that already went through ordinary rates. The fix is to adjust the basis on Form 8949, using Column (g) to add back the compensation income already reported on your W-2.10Internal Revenue Service. Instructions for Form 8949 Your correct cost basis is the strike price plus the spread that was taxed as compensation.
Using the earlier numbers: strike $10, market value at exercise $50, sale at $70. The broker may report a basis of $10 per share. The correct basis is $50, because you already paid ordinary tax on the $40 spread. Your real capital gain is $20 per share, not $60. Skipping the adjustment means paying tax twice on the same $40,000. On a large exercise that mistake alone can cost thousands.
Estimated Payments After a Large Exercise
Paycheck withholding does not stretch to cover a big option payout. A 22% flat withholding on a spread actually taxed at 35% leaves a real gap, and state taxes, the 3.8% net investment income tax, and any follow-on capital gains widen it.
To avoid an underpayment penalty, total withholding and estimated payments must equal at least the smaller of 90% of your 2026 liability or 100% of your 2025 liability, assuming your 2025 return covered a full year. If your 2025 adjusted gross income exceeded $150,000, the prior-year safe harbor becomes 110%.11Internal Revenue Service. Estimated Tax for Individuals If you exercise a large block midyear and your withholding will fall short, send a quarterly estimated payment with Form 1040-ES for the quarter the exercise occurred. Some employers can also withhold at a higher rate on supplemental wages, though not every payroll system supports it.
One last cross-check before you file: pull your W-2 and your 1099-B side by side. The compensation income from any NSO exercise or ISO disqualifying disposition should already be in W-2 Box 1, and your Form 8949 basis should reflect that. Getting those two numbers to line up is the single most valuable minute you can spend on an option return.