Key Takeaways
- AMT is a parallel tax system ensuring high-income taxpayers pay a minimum level of tax
- You calculate tax under both regular and AMT systems — you pay whichever is higher
- Common AMT triggers: incentive stock options (ISOs), accelerated depreciation, private activity bonds
- The TCJA significantly increased the AMT exemption, reducing the number of affected taxpayers
- AMT paid may generate credits (Form 8801) that can be used in future years
The Alternative Minimum Tax Explained
The Alternative Minimum Tax (AMT) is a separate, parallel tax system created by Congress to ensure that high-income taxpayers pay a minimum amount of tax regardless of how many deductions and credits they claim under the regular tax system.
When you file your taxes, you essentially calculate your tax liability twice — once under the regular system and once under the AMT system. If the AMT calculation results in a higher tax, you pay the AMT amount. Think of it as a backstop that prevents wealthy taxpayers from using excessive deductions to eliminate their tax liability entirely.
How AMT Is Calculated
The AMT calculation starts with your regular taxable income, then adds back certain deductions and preferences that are not allowed under the AMT system. These include state and local tax deductions (SALT), certain miscellaneous deductions, and the spread on exercised incentive stock options (ISOs).
After adding back these items, an AMT exemption amount is subtracted (this exemption phases out at higher income levels). The remaining amount is taxed at AMT rates (26% and 28%), and if this AMT tax exceeds your regular tax, you pay the difference as additional tax.
Who Is Affected by AMT?
Since the Tax Cuts and Jobs Act significantly increased the AMT exemption amount, far fewer taxpayers are affected. However, AMT can still apply to high-income earners who exercise incentive stock options, have large amounts of accelerated depreciation, hold private activity bonds, or have substantial state and local tax deductions.
If you think you might be subject to AMT, it is important to plan ahead. Timing of ISO exercises, depreciation methods, and investment decisions can all impact your AMT liability.
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More on Alternative Minimum Tax (AMT)
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5:18ISO and AMT: How Incentive Stock Options Trigger AMT
4:44Accelerated Depreciation and AMT: Common AMT Trigger
4:08Private Activity Bonds and AMT: What Investors Need to Know
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