Exercising options can trigger tax on money you have not received yet. Model AMT, timing, and sale together.
Free stock options and AMT calculator from Fynvorax.
Practical tip Start with round numbers from your bank or contract. You can refine decimals after the first pass.
What to enter
Have these handy before you start. Names vary by tool, but the ideas are the same.
Income, gains, or transaction amounts
Holding period or filing status where relevant
Rates or brackets that apply to your case
State or local rules if the tool supports them
Quick workflow
Enter amounts as shown on your statements.
Pick the filing options that match your situation.
Use the result as a rough check before filing.
Free calculator Estimate ISO exercise spread and AMT exposure in the stock options AMT calculator before you exercise.
Worked example (illustrative)
You exercise 5,000 ISOs at $10 strike when FMV is $45—bargain element is $175,000 added for AMT purposes even if you do not sell. Regular tax might stay lower while AMT adds a tentative minimum tax bill due with your return. A disqualifying sale later changes the story. Model shares, FMV, and income in the ISO exercise & AMT calculator; state AMT and withholding vary—not tax advice.
Common search questions
AMT tax calculator — ISO spread can trigger alternative minimum tax.
Stock options AMT calculator — exercise timing vs cash to pay AMT.
ISO exercise calculator — pair with our RSU tax tool for total equity comp.
Open the tool when you already have a quote, a deadline, or a what-if and need a clear number for taxes.
Situations people use it for
Rough-order tax impact before talking to a CPA
Comparing entity or filing structures at a high level
Estimating proceeds after tax on a sale or exercise
How to read the result
Treat the output as a structured estimate. Small input changes should move the result in a direction that makes sense.
Run a conservative case first. If it still works, you have margin.
Change one field at a time so you know what actually moved the number.
Save the scenario with a name you will recognize later ("2027 refi", "15-year plan").
This model assumes: Free stock options and AMT calculator from Fynvorax.
Common slip-ups
Using the result as if it were a tax return (it is only a model)
Using last year's brackets for a life event that changed your situation
Ignoring state/local when only federal was modeled
Try it with your numbers
Open the Stock Options & AMT Tax calculator, enter your case, and keep a screenshot or PDF if you will revisit the decision. Everything runs in your browser; your inputs are not sent to our servers for the math.