How much cash do I need to exercise ISOs?

Two things - the exercise cost itself (your strike price times the number of shares) and any alternative minimum tax triggered by the bargain element if you exercise and hold past year-end. This calculator adds both into a single cash figure.

Can I exercise and sell same day to avoid AMT?

Yes. A same-day sale is a disqualifying disposition that taxes the gain as ordinary income instead of creating an AMT preference item. You lose the favorable ISO treatment but avoid a large AMT bill on shares you have not sold.

What is the bargain element?

It is the fair market value at exercise minus your strike price, times the number of shares. It does not appear on your regular tax return when you hold, but it is added to your alternative minimum tax income.

When does the long-term capital gains clock start for ISOs?

At exercise. To get the most favorable treatment you must hold more than two years from grant and more than one year from exercise - a qualifying disposition.

ISO exercise tax calculator

Estimate the all-in cash to exercise ISOs: exercise cost plus the AMT from the bargain element.

The real cost of exercising ISOs

Exercising incentive stock options has two cash costs that catch people off guard. The first is the exercise cost - your strike price times the number of shares, which you pay to actually buy the stock. The second, easy to forget, is the alternative minimum tax the bargain element can trigger when you exercise and hold past December 31. This calculator adds both into the total cash you actually need.

Worked example

Say you exercise 10,000 ISOs with a $1 strike at an $11 fair market value, with $200,000 of other income (single):

Exercise cost: $1 × 10,000 = $10,000
Bargain element: ($11 − $1) × 10,000 = $100,000
Estimated AMT: about $17,840 (the bargain element pushes your tentative minimum tax above your regular tax)
Total cash needed to exercise and hold: roughly $27,840

So the “$10,000 to buy my shares” turns into nearly $28,000 once the AMT is counted - on shares you have not sold.

Why holding is what triggers the AMT

If you exercise and sell in the same year, there is no AMT preference - the gain is simply ordinary income (a disqualifying disposition). The AMT only appears when you hold past year-end to start the clock toward long-term capital gains treatment. So the AMT is the price of chasing the lower long-term rate.

Managing the bill

Find your AMT crossover. Use the AMT / ISO calculator to see how many shares you can exercise before AMT kicks in, and exercise up to that point each year.
Exercise early in the year. Exercising in January gives you until December to decide whether to hold (keeping the ISO treatment) or sell to undo the AMT.
Exercise when the spread is small. Right after a grant or a 409A reset, the bargain element - and the AMT - may be near zero.
Same-day sale. Convert to ordinary income and skip the AMT entirely if you need the cash or want to avoid concentration risk.

Don’t forget liquidity

For employees at private companies, the exercise cost is real cash out of pocket for shares you cannot yet sell, plus a possible AMT bill - a meaningful liquidity commitment. Make sure the company’s prospects justify tying up that cash, and never exercise more than you can afford to lose.

Common mistakes

Budgeting only the strike-price cost and being blindsided by the AMT.
Exercising a large block in December with no room to course-correct.
Holding illiquid private shares whose value could fall below the tax you already owe.

For the underlying AMT mechanics, see the AMT / ISO calculator; to compare ISO and NSO treatment, use the stock option tax calculator.

Last reviewed January 2026. This calculator provides general educational estimates based on the inputs you enter and simplified assumptions. It is not financial, tax, legal or investment advice, and figures may differ from your actual liability. Verify with a licensed CPA or financial advisor before acting.