AMT Calculator

Estimate your Alternative Minimum Tax based on your income and deductions.

What Is the Alternative Minimum Tax?

The Alternative Minimum Tax (AMT) is a parallel tax system designed to ensure that high-income individuals, trusts, and estates pay at least a minimum amount of federal income tax. It operates by disallowing certain tax breaks and deductions that are permitted under the regular tax system. If your calculated AMT liability exceeds your regular tax liability, you must pay the difference as the AMT.

This calculator estimates your tentative minimum tax (TMT) by applying the AMT rates to your alternative minimum taxable income (AMTI), which is your adjusted gross income plus specific preference items and adjustments, minus the AMT exemption amount.

How the AMT Calculation Works

The AMT calculation follows a specific sequence:

Calculate Alternative Minimum Taxable Income (AMTI): Start with your adjusted gross income (AGI). Add back certain tax preference items (e.g., private activity bond interest, certain depletion deductions) and make AMT adjustments (e.g., standard deduction, state and local tax deductions, medical expense deduction limits).
Subtract the AMT Exemption: Deduct the applicable AMT exemption amount based on your filing status. The exemption phases out at higher income levels.
Apply the AMT Tax Rates: Apply the two-tier AMT rate structure (26% and 28%) to the resulting income after the exemption.
Compare to Regular Tax: The AMT is the amount by which your tentative minimum tax exceeds your regular tax liability.

This calculator automates steps 2 and 3 based on your inputs. It assumes you have already identified your AMT adjustments and preference items.

How to Use This Calculator

To get an accurate estimate, you will need your adjusted gross income and a list of your AMT adjustments and preference items. These are typically calculated on Form 6251.

Enter your Adjusted Gross Income (AGI): This is your total income from all sources minus specific deductions, found on your tax return.
Enter your AMT Adjustments and Preferences: This is the total of all items that must be added back to your AGI for AMT purposes. Common items include state and local taxes deducted, the standard deduction, and certain medical expenses.
Select your Filing Status: This determines your AMT exemption amount and phase-out threshold.

The calculator will then compute your AMTI, apply the exemption, and calculate your tentative minimum tax.

Understanding Your Results

The result displayed is your tentative minimum tax (TMT). This is the amount of tax you would owe under the AMT system before comparing it to your regular tax.

If your TMT is higher than your regular tax liability, the difference is your AMT. If your TMT is lower, you do not owe the AMT. This calculator provides the TMT, which is the critical first step in determining your final AMT liability.

Note that this is an estimate. The actual calculation can be more complex depending on your specific financial situation, including capital gains, net operating losses, and other specialized adjustments.

Common AMT Triggers

Certain tax situations are more likely to trigger the AMT. Being aware of these can help you plan and understand your results:

High state and local taxes: These deductions are not allowed under the AMT.
Large numbers of personal exemptions: These are not allowed under the AMT.
Exercise of incentive stock options (ISOs): The bargain element can be an AMT preference item.
Interest from private activity bonds: This income is tax-free for regular tax but taxable for AMT.
Large miscellaneous itemized deductions: These are not allowed under the AMT.

Limitations of This Calculator

This calculator provides a simplified estimate and does not account for every nuance of the AMT calculation. Key limitations include:

It does not calculate the AMT credit, which may be available in future years.
It does not handle the special treatment of capital gains and qualified dividends under the AMT.
It does not account for the Net Operating Loss (NOL) deduction or other complex adjustments.
It assumes a standard phase-out of the exemption based on filing status.

For a definitive calculation, consult a tax professional or use official IRS Form 6251.

Frequently Asked Questions

What is the difference between regular tax and AMT?

The regular tax system allows for various deductions and credits to reduce your tax bill. The AMT is a separate system that disallows many of these benefits, creating a broader tax base. You pay the higher of the two calculated amounts.

Who is most likely to be affected by the AMT?

While originally intended for the very wealthy, the AMT can affect upper-middle-income taxpayers, especially those living in high-tax states, those with large families (many exemptions), or those who exercise incentive stock options.

Does the AMT exemption phase out?

Yes. The AMT exemption amount is reduced by 25% of the amount by which your AMTI exceeds a specific threshold. This phase-out effectively increases the marginal tax rate for taxpayers in the phase-out range.

Can I get a credit for AMT paid in a prior year?

Yes, in many cases. The AMT credit allows you to recapture AMT paid on certain deferral items (like the exercise of ISOs) in future years when you are not subject to the AMT. This calculator does not compute this credit.

Is this calculator a substitute for professional tax advice?

No. This tool is for estimation and educational purposes only. Tax laws are complex and subject to change. You should consult with a qualified tax professional for advice specific to your financial situation.