How the Alternative Minimum Tax Exemption Reduces Your AMT Bill

The exemption shields part of your income from the AMT calculation

The Alternative Minimum Tax exemption is a dollar amount the IRS lets you subtract from your income before calculating whether you owe AMT. Think of it as a floor: if your AMT income falls below the exemption, you owe no AMT at all. If it rises above the exemption, you only pay AMT on the amount that exceeds it.

The exemption amount changes every year and depends on your filing status. For 2024, the exemption is $85,900 for single filers and $133,900 for married filing jointly. These numbers are adjusted annually for inflation, so they will be different in 2025. The IRS publishes the current year's exemption in the AMT instructions that come with Form 6251.

Without this exemption, far more taxpayers would owe AMT. The exemption exists because Congress designed AMT to catch high-income earners who use deductions to reduce their regular tax bill to almost nothing — not to tax middle-income households. The exemption is the primary reason most people never calculate AMT at all.

Key Takeaways

The exemption is a fixed dollar amount you subtract from your AMT income; if your AMT income is below the exemption, you owe no AMT.
Exemption amounts vary by filing status and increase each year for inflation — check the Form 6251 instructions for the current year.
The exemption phases out (reduces) as your AMT income rises above a threshold, which means higher earners get less benefit from it.
You calculate the exemption on Form 6251, and it directly reduces the amount of income subject to the 26% or 28% AMT tax rates.

How the exemption amount is determined each year

The IRS sets the exemption using a formula tied to inflation. The base exemption amounts were established by Congress and are adjusted upward each January 1 to reflect the prior year's cost-of-living increase. This is why the exemption you see on Form 6251 in 2024 will not match the exemption in 2025.

You do not calculate the exemption yourself. The IRS publishes it in the Form 6251 instructions, and tax software fills it in automatically. If you are preparing the form by hand, you copy the number directly from the instructions — it is not derived from your income, deductions, or filing status beyond the status category itself.

The exemption applies to all taxpayers in your filing status equally. A single filer with $50,000 in AMT income and a single filer with $500,000 in AMT income both start with the same exemption amount. The difference is what happens next: the higher earner's exemption begins to phase out.

The phase-out: how high earners lose the exemption

As your AMT income rises above a certain threshold, your exemption shrinks. This is called the phase-out. For 2024, the phase-out threshold is $578,150 for married filing jointly and $289,075 for single filers. Once your AMT income exceeds these thresholds, you lose $0.25 of exemption for every $1.00 of income above the threshold.

This phase-out means the exemption does not protect high-income earners as much as it protects middle-income earners. A married couple with $600,000 in AMT income loses $5,462.50 of their $133,900 exemption (because $600,000 − $578,150 = $21,850, and $21,850 × 0.25 = $5,462.50). The phase-out is built into Form 6251, and tax software calculates it automatically.

The phase-out thresholds also adjust for inflation each year, so they will be different in 2025. The instructions to Form 6251 always show the current year's thresholds.

Where the exemption appears on Form 6251

The exemption calculation happens on Form 6251, Alternative Minimum Tax — Individuals. You will find it in the middle section of the form, after you have calculated your AMT income but before you calculate the tax itself.

Line 3 of Form 6251 is where you enter your exemption amount (or where tax software enters it for you). You then subtract this amount from your AMT income on line 4 to get your AMT taxable income. This AMT taxable income is what gets multiplied by the 26% or 28% AMT tax rate to produce your AMT liability.

If you use tax software, the exemption is filled in automatically based on your filing status and the current year. If you prepare Form 6251 by hand, you look up the exemption in the instructions and copy it onto line 3. You do not calculate it yourself.

Why the exemption matters to your tax bill

The exemption is the single most important factor in determining whether you owe AMT at all. Because the exemption is substantial — $85,900 or more depending on filing status — most taxpayers never reach the point where AMT applies. The exemption does the heavy lifting of keeping AMT from affecting people it was not designed to reach.

For someone whose AMT income is $100,000 and filing status is single, the exemption of $85,900 means only $14,100 is subject to the AMT tax rate. That $14,100 × 26% = $3,666 in AMT. Without the exemption, the full $100,000 would be taxed, producing $26,000 in AMT — a difference of $22,334.

The exemption also means that if your AMT income falls below the exemption amount, you owe zero AMT, period. You do not owe a partial amount or a minimum. This is why calculating your AMT income accurately is the first step: if it is below the exemption, you are done.

When the exemption does not help much

If your AMT income is very high, the phase-out reduces the exemption so much that it provides little protection. A single filer with $1,000,000 in AMT income loses nearly all of their exemption to the phase-out. At that income level, the exemption shrinks to almost nothing, and AMT becomes a real tax liability.

High-income earners — particularly those with substantial capital gains, stock options, or large deductions for state and local taxes — are the ones for whom AMT remains a genuine concern. The exemption still applies to them, but it is phased out so far that it does not reduce their AMT bill by much.

This is intentional. AMT was designed to prevent high-income taxpayers from using deductions to eliminate their tax liability. The exemption protects middle-income households from AMT, but it does not shield high earners from the tax's intent.

How to find the current exemption amount

The IRS publishes the exemption amount in the instructions to Form 6251 every year. You can find these instructions on IRS.gov by searching for "Form 6251 instructions" and the current tax year. The exemption is listed near the top of the instructions, in a table organized by filing status.

Tax software looks up the exemption automatically based on the tax year you are filing for and your filing status. You do not need to search for it yourself if you are using software. If you are preparing the form by hand, print the instructions and copy the number directly — do not try to calculate it or estimate it.

The exemption for prior years is also available in the archived Form 6251 instructions on IRS.gov, in case you need to amend a return from a previous year.

Frequently Asked Questions

Can I claim a higher exemption if I have dependents or a lower income?

No. The exemption is based only on your filing status, not on your income level, number of dependents, or other factors. All single filers get the same exemption amount; all married filing jointly filers get the same exemption amount. The only thing that changes the exemption is inflation adjustment and your filing status.

What happens if my AMT income is exactly equal to the exemption amount?

You owe no AMT. The exemption is subtracted from your AMT income, leaving zero AMT taxable income. Zero times any tax rate is zero. You would report AMT on Form 6251 but owe nothing.

Does the exemption explore to the AMT I owe on capital gains?

Yes. The exemption reduces your total AMT income before any tax rate is applied. Capital gains are included in AMT income, and the exemption applies to your total AMT income, which includes those gains. You do not calculate a separate exemption for capital gains.

If I am married filing separately, do I get half the married filing jointly exemption?

No. Married filing separately has its own exemption amount, which is lower than married filing jointly. The IRS publishes the married filing separately exemption in the Form 6251 instructions. It is not half of the joint amount.

Does the exemption phase-out affect my regular income tax, or only my AMT?

Only your AMT. The exemption and its phase-out are part of the AMT calculation on Form 6251. They have no effect on your regular income tax calculation on Form 1040. The two tax systems are separate.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.