BEHIND THE NUMBERS
How this calculation works
Worked example
ISO spread of 1,000 × $100 creates $100,000 AMTI. Subtract the $90,100 exemption: $9,900 × 26% = $2,574 AMT; regular tax is zero.
Example result: US$2,574.00
Start with the right income number
AMTI is a tax base constructed from the return, not a synonym for wages. Incentive stock options, deductions, tax preferences and timing differences can all change it. This tool avoids guessing those adjustments: prepare Part I first, then enter the result and the appropriate regular-tax comparison amount.
What the additional amount means
An AMT result is the positive excess of tentative minimum tax over the regular-tax comparison. It is not the total tax bill and should not be compared with payroll withholding. A zero result means no additional AMT in this supported calculation; it does not establish that every other tax calculation is correct.
Assumptions and rounding
- The 2026 exemption is $90,100 single/HOH, $140,200 joint/survivor or $70,100 separate.
- Phase-out starts at $500,000, or $1,000,000 for joint/survivor returns.
Questions about this calculator
Do I have to calculate AMTI first?
No. Income mode derives it for the supported wage, investment and ISO scenario.
Are qualified dividends handled?
Yes, with the 0%, 15% and 20% bands used in the Form 6251 Part III comparison.