What Is the Alternative Minimum Tax (AMT) and How Does It Work?

For many taxpayers, AMT never comes into play. But for higher-income individuals, executives exercising incentive stock options, business owners, and investors experiencing significant income or capital gains, understanding the AMT before a major financial decision can help prevent an unexpected tax bill.

Why Does the Alternative Minimum Tax Exist?

Congress originally enacted the AMT in 1969 after discovering that a small number of high-income taxpayers were legally paying little or no federal income tax because of deductions and other tax preferences.

The AMT was designed as a backstop. It limits or changes the treatment of certain tax benefits available under the regular tax system to establish a minimum level of federal income tax for affected taxpayers.

How Does the Alternative Minimum Tax Work?

At a high level, taxpayers potentially subject to AMT calculate their federal income tax twice:

1. Calculate tax under the regular federal income tax system.
2. Recalculate income under the AMT rules to determine Alternative Minimum Taxable Income (AMTI).
3. Apply the applicable AMT exemption and tax rates.
4. Compare the tentative minimum tax with regular tax liability.

If the resulting AMT calculation exceeds the taxpayer’s regular income tax liability, the difference may be owed as AMT.

For tax year 2026, the AMT exemption is $90,100 for unmarried individuals and $140,200 for married couples filing jointly. The exemption begins phasing out at $500,000 and $1 million of AMTI, respectively. The AMT generally uses 26% and 28% tax rates, although qualified dividends and capital gains may receive preferential rates.

What Can Trigger the Alternative Minimum Tax?

AMT exposure depends on your complete tax situation, but several financial events and tax preference items can increase the likelihood of owing AMT.

1. Exercising Incentive Stock Options

An incentive stock option (ISO) exercise is one of the most important AMT considerations for executives and employees with equity compensation.

For regular income tax purposes, exercising an ISO generally does not create ordinary income at exercise. For AMT purposes, however, the difference between the stock’s fair market value and the exercise price may be included as an AMT adjustment.

A substantial ISO exercise can therefore create an AMT liability even when the shares have not been sold.

2. Certain Private Activity Municipal Bonds

Interest from certain private activity bonds may be tax-exempt for regular federal income tax purposes but treated as a preference item for AMT purposes.

Investors with significant municipal bond portfolios should understand whether any holdings could affect their AMT calculation.

3. Business Depreciation and Pass-Through Adjustments

Different depreciation rules can create AMT adjustments for certain business assets. Partnerships and S corporations can also pass AMT-related adjustments through to their owners.

4. Large Capital Gains

Long-term capital gains generally retain their preferential tax rates under the AMT system. However, a significant capital gain can increase AMTI and potentially reduce or eliminate the taxpayer’s AMT exemption.

As a result, selling a business, concentrated stock position, investment property, or another highly appreciated asset may warrant an AMT projection before the transaction occurs.

How Can You Reduce or Plan for AMT?

The most effective approach to AMT is often proactive tax planning before a taxable event occurs.

Depending on your circumstances, planning strategies may include spreading income or ISO exercises across multiple tax years, coordinating the timing of capital gains, reviewing municipal bond exposure, and maximizing appropriate tax-advantaged savings opportunities such as retirement plan and Health Savings Account contributions.

Charitable planning may also play a role as part of a broader income and tax strategy.

The key is to model these decisions together. A strategy that lowers regular taxable income does not necessarily produce the same result under the AMT calculation.

Can You Get AMT Back in Future Years?

Sometimes.

Certain AMT liabilities result from timing differences rather than permanent differences in taxable income. When this happens, a taxpayer may qualify for the Minimum Tax Credit in a future year.

The credit may allow taxpayers to recover some or all of qualifying AMT previously paid when their regular tax liability exceeds their tentative minimum tax in a subsequent year. Eligibility and the amount available depend on the source of the prior AMT and the taxpayer’s future tax situation.

When Should You Run an AMT Projection?

Consider preparing both a regular income tax projection and an AMT projection before year-end if you anticipate a significant financial event, including:

• Exercising a substantial number of incentive stock options
• Selling highly appreciated investments
• Selling a business or other major asset
• Receiving significant pass-through business income
• Realizing an unusually large capital gain
• Making other decisions that could materially change taxable income

Running projections before completing a transaction gives you more opportunity to adjust the timing or structure of the decision.

Frequently Asked Questions About the Alternative Minimum Tax

1. What is the Alternative Minimum Tax in simple terms?
   The AMT is a separate federal tax calculation that limits certain deductions and tax preferences. Taxpayers potentially subject to AMT calculate their tax under both the regular and AMT systems and may owe additional tax when the AMT calculation produces the higher liability.
2. What income level triggers AMT?
   There is no single income level at which everyone begins owing AMT. Filing status, deductions, incentive stock option exercises, investment income, capital gains, and other AMT adjustments all affect the calculation. For 2026, the AMT exemption begins phasing out when AMTI exceeds $500,000 for unmarried taxpayers or $1 million for married couples filing jointly.
3. Do incentive stock options trigger AMT?
   They can. When an ISO is exercised, and the shares are held beyond the year of exercise, the difference between the stock’s fair market value at exercise and the exercise price generally creates an AMT adjustment. The larger the spread, the greater the potential AMT exposure.
4. Are capital gains subject to AMT?
   Capital gains generally retain their preferential federal tax rates under the AMT calculation. However, a large gain can increase AMTI and cause the AMT exemption to phase out, potentially increasing overall AMT exposure.
5. Is AMT an additional tax on top of regular income tax?
   AMT operates alongside the regular income tax system. Taxpayers calculate their liability under both systems, and when the tentative minimum tax exceeds regular tax liability, the difference generally becomes AMT owed.

Planning Ahead for the Alternative Minimum Tax

The AMT depends heavily on your overall income, investments, equity compensation, deductions, and the timing of financial decisions. That makes forward-looking planning particularly important.

Before exercising significant stock options, realizing a large capital gain, selling a business, or completing another major transaction, consider modeling both your regular federal income tax and AMT exposure. Coordinating these decisions with your broader financial plan can help identify opportunities to manage taxes while keeping your long-term financial priorities at the center of the strategy.

A Mission Wealth advisor working alongside your tax professional can help evaluate how major income events affect not only this year’s tax bill, but also your investments, cash flow, diversification strategy, and long-term financial plan.