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AMT calculator for ISO exercise.
Free AMT calculator for tech employees exercising ISOs. Inputs W-2 income, ISO grant, strike price, FMV, exercise quantity. Outputs estimated AMT bite, AMT credit eligibility, dual-basis adjustment, and disqualifying-disposition impact.
Educational only · not investment, tax, or legal advice · confirm with your CPA
Common questions about this calculator.
What is AMT for ISO exercise?
Alternative Minimum Tax is a parallel tax system that catches ISOs at exercise even though regular tax doesn't. The "spread" between strike and FMV at exercise becomes AMT income. The 2026 AMT exemption is $86,200 single / $137,000 MFJ; phaseout starts at $626,350 / $1,252,700.
Is the AMT credit recoverable?
Yes — AMT paid on ISO exercise creates a Minimum Tax Credit you can use to offset future regular tax (when regular tax exceeds tentative minimum tax). The credit can be used against ordinary income in subsequent years until exhausted.
What is the dual-basis problem?
When you exercise ISOs and pay AMT, your "AMT basis" in the shares = strike + AMT-recognized spread. Your regular-tax basis stays at strike. When you sell, you have two different bases for AMT vs regular tax — and the bigger AMT basis reduces AMT gain. Most tax software gets this wrong; HELM tracks both bases automatically.
What is a disqualifying disposition?
Selling ISOs within 1 year of exercise OR within 2 years of grant. Disqualifying disposition converts ordinary-income treatment for the spread instead of capital gain. Often beneficial in HIGH-AMT years (you can claw back AMT credit faster), often costly in low-AMT years.