What Is the Alternative Minimum Tax (AMT)?
The Alternative Minimum Tax (AMT) is a parallel tax system in the United States designed to ensure that high-income taxpayers who benefit from certain deductions, credits, and exclusions pay at least a minimum amount of tax. Created in 1969 after it was discovered that 155 wealthy individuals paid zero federal income tax, the AMT adds back certain tax preference items and applies a separate set of rates and exemptions to determine if you owe additional tax beyond your regular tax liability.
The AMT works by calculating your Alternative Minimum Taxable Income (AMTI), subtracting an AMT exemption, and applying AMT tax rates (26% and 28%). If your tentative minimum tax exceeds your regular tax, you pay the difference as AMT. After the Tax Cuts and Jobs Act (TCJA) of 2017, the number of taxpayers subject to AMT decreased dramatically due to higher exemption amounts, but it still affects many taxpayers, particularly those who exercise incentive stock options (ISOs) or have high state and local taxes.
The most common AMT triggers are: (1) exercising incentive stock options (ISOs), (2) high state and local tax (SALT) deductions, (3) large long-term capital gains, and (4) certain tax-exempt interest from private activity bonds.
How the AMT Is Calculated
AMT Exemption Amounts (2026)
| Filing Status | AMT Exemption | Phase-Out Begins | Phase-Out Complete |
|---|---|---|---|
| Single / Head of Household | $88,100 | $609,350 | $961,750 |
| Married Filing Jointly | $137,000 | $1,218,700 | $1,766,700 |
| Married Filing Separately | $68,500 | $609,350 | $883,350 |
Common AMT Adjustment Items
- State and local income taxes (SALT): The largest AMT adjustment for most taxpayers; fully added back for AMT purposes
- Incentive stock option (ISO) exercise spread: The difference between the fair market value and exercise price is an AMT preference item in the year of exercise
- Private activity bond interest: Tax-exempt interest from private activity municipal bonds is included in AMT income
- Depreciation differences: AMT uses different depreciation methods than regular tax for certain assets
- Standard deduction: If you take the standard deduction for regular tax, it is not allowed for AMT (but this rarely triggers AMT)
- Medical expense threshold: AMT uses a 10% AGI threshold for medical deductions (same as regular tax after TCJA)
- Net operating loss: AMT NOL is calculated differently and may not fully offset AMTI
- 1Step 1: Calculate AMTI = $200,000 + $25,000 + $50,000 = $275,000
- 2Step 2: AMT Exemption (single) = $88,100
- 3Step 3: AMTI exceeds phase-out? $275,000 < $609,350, so full exemption applies
- 4Step 4: AMT base = $275,000 - $88,100 = $186,900
- 5Step 5: Tentative minimum tax = $186,900 x 26% = $48,594
- 6Step 6: AMT = $48,594 - $42,000 = $6,594
AMT and Stock Options: What You Need to Know
Incentive stock options (ISOs) are one of the most common triggers for AMT liability. When you exercise ISOs, the bargain element (the difference between the fair market value at exercise and the exercise price) is not taxed for regular income tax purposes but is included as an AMT adjustment item. This can create a significant and unexpected AMT bill, especially in years when stock prices rise sharply.
To manage ISO-related AMT risk, consider exercising options gradually over multiple years rather than all at once, exercise early in the tax year when stock prices may be lower, or consider a same-day sale (which eliminates the AMT adjustment but converts the gain to ordinary income). The AMT credit (Form 8801) allows you to recover AMT paid on timing differences like ISOs in future years when your regular tax exceeds your tentative minimum tax.
Strategies to Minimize AMT
AMT Reduction Strategies
The AMT calculations shown here are estimates based on simplified assumptions. The actual AMT calculation involves numerous adjustments and interactions that may affect your result. Always consult a qualified tax professional for accurate AMT planning, especially if you exercise incentive stock options.