Top 3 things you need to know before you do a cashless exercise of your incentive stock options

A cashless exercise is the button in your brokerage portal that turns incentive stock options (ISOs) into cash without writing a check: you exercise and sell the same day, and the broker pays the strike price out of the proceeds. It is convenient, and it throws away the one tax feature that makes an ISO different from an ordinary option. Here are the three things that matter before you click, then the reporting mechanics, the AMT math, the $100,000 rule and a worked comparison.

1. A same-day cashless exercise is a disqualifying disposition

An ISO gets favorable tax treatment only if you hold the shares long enough. Under Internal Revenue Code section 422(a)(1), you must not sell the shares within two years of the grant date or within one year of the exercise date. Meet both tests and the entire gain from strike price to sale price is a long-term capital gain. Fail either test and the sale is a "disqualifying disposition."

A cashless exercise sells the shares the same day you exercise, so it fails the one-year test by definition. The result, per IRS Publication 525, is that the spread between the exercise price and the fair market value at exercise (the "bargain element") is taxed as ordinary wage income, exactly as a cash bonus would be. The ISO is treated, in effect, as a non-qualified stock option.

• You pay your marginal ordinary rate on the spread. For most tech employees that is 24%, 32% or 35% federal in 2026 (Rev. Proc. 2025-32), plus state tax.
• You give up the long-term capital gains rate of 0%, 15% or 20%. In 2026 the 15% rate applies to single filers with taxable income between $49,450 and $545,500, and to joint filers between $98,900 and $613,700 (Rev. Proc. 2025-32, section 3.03).
• There is no AMT. The one upside: because regular-tax and AMT treatment are identical when you sell in the year of exercise, the Form 6251 instructions say no adjustment is required.

2. Sell-to-cover is the middle path most people never see

The portal usually offers three choices: pay cash and hold everything, sell everything, or "sell to cover." Sell-to-cover exercises all of your options but sells only enough shares to pay the strike price (and sometimes an estimate of tax). The shares sold are a disqualifying disposition; the shares kept start their one-year holding clock.

The shares you keep are still ISO shares: hold them past the one-year and two-year marks and their gain is long-term capital gain. You have funded the exercise from the position itself and limited the ordinary-income hit to the shares you sold. Sell-to-cover also softens the AMT problem described next, because the ordinary income on the sold shares raises your regular tax at the same time the held shares raise your AMT income; in the worked example below it produces no AMT at all.

The cost is concentrated exposure to one stock. That is a risk decision, not a tax decision. If you also hold restricted stock units in the same company, our RSU tax guide explains why "sell at vest" is the default there; weigh how much total employer stock you are comfortable holding.

3. Exercise-and-hold trades ordinary income for AMT risk

The textbook ISO strategy is to exercise, pay the strike in cash, hold for the required periods and sell at long-term rates. For regular tax there is no income at exercise (section 421(a)). The catch is the alternative minimum tax: the bargain element is an AMT adjustment (Form 6251 line 2i), and if your tentative minimum tax exceeds your regular tax you pay the difference in the year of exercise, before selling a share.

1. The exemption. For 2026 the AMT exemption is $90,100 for single filers and $140,200 for joint filers, phasing out above $500,000 and $1,000,000 of AMT income respectively (Rev. Proc. 2025-32, section 3.10). A large part of your income is shielded before the 26% rate starts.
2. The credit. AMT paid on an ISO exercise generates a minimum tax credit (Form 8801) usable in later years when regular tax exceeds tentative minimum tax, typically the year you sell. You are prepaying tax, not losing it, though recovery can take years.

The real risk is a price drop. Exercise at $60, pay AMT on a $40 spread, and if the stock falls to $30 you have paid tax on value that no longer exists, with the credit coming back slowly. The ISO AMT calculator models how many shares you can exercise before AMT kicks in at your income level; many people exercise up to that line each year and no further.

How the income gets reported

Form 3921, every time

Whenever you exercise an ISO, the company must file Form 3921 with the IRS and give you a copy. It reports the grant and exercise dates, the exercise price, the fair market value per share on the exercise date and the number of shares, and you receive it whether you hold or sell. It is the document used to compute either the AMT adjustment or the ordinary income on a disqualifying disposition.

W-2 for a disqualifying disposition

When you sell in a disqualifying disposition, Publication 525 says your employer "should report the ordinary income to you as wages in box 1 of Form W-2." Two quirks: under section 421(b) no federal income tax withholding is required on that income, so unlike a non-qualified option exercise nothing is withheld at the default 22% supplemental rate and the tax is simply due with your return (set the money aside or make an estimated payment); and under section 3121(a)(22) the income is not subject to Social Security or Medicare tax.

Form 1099-B basis trap

Your broker's 1099-B often shows a cost basis equal to only the strike price. The correct basis after a disqualifying disposition is the strike price plus the ordinary income on your W-2. Adjust it on Form 8949 or you pay tax on the spread twice. It is the most common ISO return error.

The AMT math if you hold

Alternative minimum taxable income starts from your regular taxable income, adds back items the AMT does not allow (for most tech employees, the standard deduction or state and local taxes), and adds the ISO bargain element. Subtract the exemption, apply 26% to the first $244,500 of what is left and 28% above that (Rev. Proc. 2025-32 section 3.10, for all filers except married filing separately), and compare the result with your regular tax. The excess is your AMT.

Step (single filer, 2026)	Amount
Regular taxable income before ISO exercise	$300,000
Add back standard deduction (Form 6251 line 2a)	$16,100
Add ISO bargain element (2,000 shares x $40 spread)	$80,000
AMT income	$396,100
Less AMT exemption (no phase-out below $500,000)	($90,100)
Taxable excess	$306,000
Tentative minimum tax: 26% x $244,500 + 28% x $61,500	$80,790
Regular tax on $300,000 (Rev. Proc. 2025-32 Table 3)	$71,961
AMT due in the exercise year	$8,829

Holding costs $8,829 of AMT up front, recoverable later through the Form 8801 credit. Note how much work the exemption does, and that it begins to phase out at $500,000 of AMT income for single filers: a very large exercise in one year is punished twice, by the spread and by the shrinking exemption. Spreading exercises across tax years is the standard response.

The $100,000 ISO limit

Section 422(d) caps the value of options that can be treated as ISOs: to the extent the aggregate fair market value of stock (measured at grant) for which ISOs first become exercisable in any calendar year exceeds $100,000, the excess options are treated as non-qualified options. Companies apply it in grant order and usually show the ISO/NSO split on your grant paperwork.

If you were granted 50,000 options at a $10 grant-date value vesting evenly over four years, $125,000 of value vests each year, so about $25,000 of value per year is NSO and is taxed as ordinary income at exercise, with withholding, however you exercise. Check your grant notice for the ISO/NSO split before planning around ISO treatment; our stock options explainer covers how the two types differ.

Worked example: cashless vs sell-to-cover vs hold

Assumptions: single filer, 2026 federal rates, regular taxable income of $300,000 before the option event (so the whole spread falls in the 35% bracket), 2,000 ISOs with a $20 strike, stock at $60 on the exercise date and still $60 when held shares are sold after the holding periods are met. Long-term gains are taxed at 15% plus the 3.8% net investment income tax, which applies above $200,000 of modified adjusted gross income for single filers (IRS NIIT page). State tax is ignored; figures are rounded.

Item	A. Cashless, same day	B. Sell-to-cover	C. Exercise and hold
Shares sold at exercise	2,000	667 (covers $40,000 strike)	0
Cash you put in	$0	$0	$40,000
Ordinary income (W-2 box 1)	$80,000	$26,680	$0
Federal tax on that income at 35%	$28,000	$9,338	$0
AMT adjustment on held shares	$0	$53,320	$80,000
AMT due in exercise year	$0	$0	$8,829 (creditable later)
Long-term gain when held shares sold	n/a	$53,320	$80,000
Tax on that gain at 18.8%	n/a	$10,024	$15,040
Total permanent federal tax	$28,000	$19,362	$15,040
Shares still held after exercise	0	1,333	2,000

Path B produces no AMT because the ordinary income on the sold shares raises regular tax ($81,299) above the tentative minimum tax ($80,790). Path C saves $12,960 of permanent tax against Path A but requires $48,829 of cash in the exercise year and exposes you to a price fall on 2,000 shares. Path A alone carries no market risk after the exercise date. None is "right"; the point is to see what the convenience of selling everything costs.

At six-figure spreads the interaction with state tax, estimated payments and the exemption phase-out gets complicated; see our page on planning for high earners. If the company has not gone public yet, start with the private company equity guide.

Common mistakes

1. Treating a cashless exercise as tax-free because nothing was withheld. No withholding is required on an ISO disqualifying disposition. The tax is still due in April.
2. Not knowing the ISO/NSO split. The $100,000 rule means part of a large grant is probably an NSO, with different rules and withholding.
3. Using the 1099-B basis without adjustment. Add the W-2 income to your strike price or you will be taxed twice on the spread.
4. Exercising a huge block in one year to "get it over with." The AMT exemption phases out above $500,000 (single) of AMT income, so lumping exercises compounds the bill.
5. Missing the two-year clock. Holding one year after exercise is not enough if the grant is less than two years old.
6. Ignoring the three-month post-termination window. Under section 422(a)(2) an option exercised more than three months after you leave is no longer an ISO.

Rates and thresholds change every year. Verify the current figures in the IRS revenue procedure for the tax year, the Form 6251 instructions and your plan documents before acting.

Related guides

• What is Amazon's RSU vesting schedule, and how are Amazon RSUs taxed?
• RSU taxes: a tech employee's guide to tax on restricted stock units
• Amazon RSUs, not stock options: your choices for building wealth
• Everything you need to know about your private company equity compensation