AMT Calculator
Calculate the Alternative Minimum Tax (AMT), a parallel tax system designed to ensure high-income taxpayers pay a minimum amount of tax regardless of deductions.
How AMT Works
The AMT is calculated alongside regular tax, and you pay whichever is higher. It disallows certain deductions and uses different exemptions and rates.
2024 AMT Parameters
| Parameter | Single | Married Filing Jointly | Exemption$85,700$133,300 Phase-out starts$609,350$1,218,700 Phase-out complete$952,150$1,751,900 26% rateFirst $220,700First $220,700 | 28% rate | Above $220,700 | Above $220,700 |
AMT Calculation
``javascript
function calculateAMT(taxableIncome, preferences, filingStatus = 'single') {
const exemption = filingStatus === 'married' ? 133300 : 85700;
const phaseoutStart = filingStatus === 'married' ? 1218700 : 609350;
const breakpoint = 220700;
// Calculate AMTI (AMT Income)
// Add back preferences (SALT, certain deductions, ISO exercise, etc.)
const amti = taxableIncome + (preferences.salt || 0) +
(preferences.isoSpread || 0) +
(preferences.miscDeductions || 0);
// Calculate exemption reduction (25% of excess)
const excessOverPhaseout = Math.max(0, amti - phaseoutStart);
const exemptionReduction = Math.min(exemption, excessOverPhaseout * 0.25);
const effectiveExemption = exemption - exemptionReduction;
// Calculate tentative AMT
const amtBase = Math.max(0, amti - effectiveExemption);
let tentativeAMT = 0;
if (amtBase <= breakpoint) {
tentativeAMT = amtBase * 0.26;
} else {
tentativeAMT = breakpoint * 0.26 + (amtBase - breakpoint) * 0.28;
}
return {
amti,
exemption: effectiveExemption,
amtBase,
tentativeAMT: tentativeAMT.toFixed(2)
};
}
``
Common AMT Triggers
| AMT Preference Item | Effect | State/local tax deduction (SALT)Added back for AMT Incentive Stock Options (ISO)Spread taxed under AMT Private activity bond interestAdded back Accelerated depreciationDifference added back | Large capital gains | Can push into AMT |
Who Gets Hit by AMT?
Since the 2017 tax law increased regular tax rates and capped SALT at $10k, fewer taxpayers trigger AMT. Those most at risk:
- ISO exercise with large spread
- High income with significant preferences
- Large capital gains in certain situations