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ISO Exercise Calculator

Estimate the cash needed to exercise incentive stock options and calculate your simplified AMT reserve based on the spread between fair market value and strike price.

Quick answer: Estimate ISO exercise cash and a simplified AMT reserve from positive spread and a user-entered tax-rate assumption. Enter Shares Exercised, Strike Price, Fair Market Value at Exercise, and AMT Rate to personalize the estimate. It returns AMT Preference Income, Cost to Exercise, and Simplified AMT Reserve Estimate so you can compare the impact before choosing a next step. Use it to compare long-term value, tax impact, risk, time horizon, and contribution choices.

SWReviewed by SwitchWize Research Desk · Last reviewed July 14, 2026
AMT Preference Income
$60,000
AMT Preference Income
$60,000
Cost to Exercise
$15,000
Simplified AMT Reserve Estimate
$15,600
Total Cash Needed
$30,600
Diagnostic

Exercising these options costs $15,000, plus a simplified $15,600 AMT reserve estimate.

The combined planning amount is about $30,600, before a full regular-tax and AMT calculation.

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What to do next

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Your action plan
  1. 1

    Set the target and timeline for this plan

    Estimate ISO exercise cash and a simplified AMT reserve from positive spread and a user-entered tax-rate assumption.

  2. 2

    Check the assumptions before using the result for a high-stakes decision

    Assumptions change the answer, especially when rates, taxes, or timing matter.

  3. 3

    Save the result to Money Map or use the linked next action

    Turn the result into a prioritized action instead of treating it as a one-off number.

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This is an educational estimate, not tax, legal, investment, or lending advice. Tax rules, rates, and eligibility change and depend on your full situation. Confirm with a qualified professional or the provider before acting.

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Frequently Asked Questions

Everything you need to know.

What does an example ISO Exercise Calculator calculation look like?
Using this calculator's own default assumptions, a shares exercised of 5000, strike price of $3 and fair market value at exercise of $15 produces an estimated amt preference income of $60,000 and cost to exercise of $15,000. Enter your own numbers above to see how it changes for your situation.
Why do I have an AMT liability on ISO exercise if I haven't sold the shares yet?
The AMT system treats the spread between fair market value and strike price as income in the year you exercise, even though you haven't realized any cash gain. This is an AMT preference item that can trigger AMT tax liability independent of your regular income tax situation.
What's the difference between the AMT reserve and the cost to exercise?
The cost to exercise is the actual cash you need to pay to buy the shares at the strike price. The AMT reserve estimate is a separate potential tax liability based on the spread; you may owe this to the IRS in addition to the purchase cost, depending on your overall tax situation.
Is the ISO Exercise Calculator free to use?
Yes. SwitchWize calculators are free, and you do not need an account to run scenarios or view the result.
Does using the ISO Exercise Calculator affect my credit score?
No. Using a calculator does not trigger a credit check. A credit impact can occur only if you apply directly with a lender, card issuer, or provider.
Are the results personalized financial advice?
No. Calculator outputs are educational estimates based on the inputs you enter. Review assumptions and confirm terms directly with providers before making a financial decision.
What should I do after seeing the result?
Use the recommendation module on this page to compare brokerage accounts, or run Money Map to compare this investing & retirement decision with your other opportunities.
How does SwitchWize choose related offers?
Related offers are matched by the calculator surface (brokerage) and ranked using SwitchWize data such as rate, fees, trust signals, product fit, and switching friction. Paid relationships do not change organic ranking order.
How fresh are the rates and offers shown?
Rate and offer data is reviewed on a recurring cadence and every offer module shows review context or links to the methodology and disclosure pages.
Where can I see the ranking methodology?
The SwitchWize methodology page explains how rate freshness, editorial review, affiliate disclosure, and category ranking factors work.
Can Money Map use this result?
Yes. Money Map is the broader diagnostic path: it compares savings, mortgage, cards, and debt so you can see whether this calculator result is your highest-impact next move.

Why This Matters

When you exercise ISOs, you create a potential AMT liability if the spread between fair market value and your strike price is positive. Understanding this upfront helps you plan for both the cash needed to buy shares and the tax reserve you may need to set aside, since AMT can apply even if you owe no regular income tax that year.

How to Use It

  1. 1Enter the number of shares you plan to exercise.
  2. 2Enter your strike price per share.
  3. 3Enter the fair market value per share at the time of exercise.
  4. 4Enter your assumed tax rate to estimate the AMT reserve.
  5. 5Review the cost to exercise, AMT preference income, simplified AMT reserve estimate, and total cash needed.
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