Alternative Minimum Tax History: From 1969 to Today

The alternative minimum tax has a history that spans more than fifty years and at least eight major laws, moving from a narrow 1969 surcharge aimed at 155 wealthy non-payers to a parallel tax system that once threatened tens of millions of middle-class households, then narrowed again after 2017 to reach only about 200,000 taxpayers. What follows is how the AMT got from there to here.

1969: A Political Firestorm Creates the First Minimum Tax

In January 1969, outgoing Treasury Secretary Joseph Barr told the Joint Economic Committee that 155 taxpayers earning more than $200,000 had paid zero federal income tax in 1966.¹ That $200,000 exceeded $1.5 million in today’s dollars. The disclosure produced more public anger than any other tax story that year, and Congress moved fast.

The Tax Reform Act of 1969 answered with a “minimum tax for tax preferences.”² It was not a parallel calculation. It worked as an add-on: if a taxpayer’s preference items (accelerated real estate depreciation, capital gains exclusions, and similar shelters) exceeded a threshold, they owed an extra 10% on the excess, on top of their regular tax. The design was blunt but narrow, going after specific shelter techniques rather than reworking the tax code.

1978: A True Parallel Tax Appears

The add-on had a structural flaw. A surcharge on preference items did not guarantee the taxpayer ended up owing a meaningful total. So the Revenue Act of 1978 created something new alongside it: a real alternative minimum tax that required a second computation, with the taxpayer paying whichever number was higher.³

This early AMT used graduated rates of 10%, 20%, and 25% with a $20,000 exemption.³ For a few years the old add-on and the new AMT ran side by side, so a taxpayer could owe either or both.

1982: TEFRA Sets the Architecture That Still Governs Today

The Tax Equity and Fiscal Responsibility Act of 1982 ended the dual system.⁴ TEFRA repealed the individual add-on minimum tax, broadened the AMT base, and set a single flat AMT rate of 20%.³ From then on, the concept was straightforward: compute the tax the normal way, compute it again under AMT rules with fewer deductions, pay the larger figure.

TEFRA also pulled new items into the calculation, including certain tax-exempt interest and incentive stock options. The parallel-computation-on-an-expanded-base framework it built is still the foundation of the AMT in 2026.

1986: A Rate Increase, a Corporate AMT, and One Costly Omission

The Tax Reform Act of 1986 rewrote federal tax law more thoroughly than any bill before or since.⁵ For the AMT, it raised the rate from 20% to 21%, adjusted exemption amounts, and introduced a corporate alternative minimum tax so that profitable companies also paid a baseline amount.

One decision from 1986 shaped the next 26 years of AMT policy: Congress did not index the exemption amounts for inflation. Regular income tax brackets moved upward with prices, but the AMT exemption stayed frozen in nominal dollars. As wages grew with the broader economy, those fixed thresholds sheltered less income every year. A tax written to catch the very rich began drifting steadily toward the middle class.

1993: The Two-Tier Rate Structure

The Omnibus Budget Reconciliation Act of 1993 replaced the flat 21% AMT rate with the two-tier structure that still applies: 26% on the first slice of AMT income above the exemption and 28% above that.⁶ The statutory dividing line sits at $175,000 of AMT income above the exemption, with an annual inflation adjustment.⁷

The higher rates made the frozen-exemption problem worse. Taxpayers who crossed the unindexed threshold now owed more than they would have at 21%. The tax reached further and hit harder at the same time.

The Patch Era

By the early 2000s, the frozen exemptions had produced a genuine crisis. Without action, the number of households owing AMT was projected to jump from roughly one million to tens of millions within a few years. Congress responded with short-term fixes, known informally as the “AMT patch,” that raised the exemption for one or two years at a time.

The patches became an annual ritual, usually attached to year-end tax packages. Taxpayers often could not know their real liability until Congress acted in late December, and the IRS sometimes delayed processing returns while it waited. Every filing season began with the same question: would Congress patch it again? The answer was always yes, but the uncertainty made planning difficult and showed how far the tax had wandered from its original target.

2012: Permanent Inflation Indexing

The American Taxpayer Relief Act of 2012 ended the patch cycle.⁸ Enacted as Public Law 112-240, it set higher exemption amounts and permanently indexed them to the Consumer Price Index.⁹ For 2013, the exemption was $51,900 for single filers and $80,800 for married couples filing jointly, and those figures would rise automatically each year.

Automatic indexing delivered what a decade of patches never could. Taxpayers no longer needed a last-minute vote to know where they stood, the IRS could plan return processing, and the tax stopped its slow march into the middle class.

2017: TCJA Sharply Narrows the Individual AMT and Kills the Corporate Version

The Tax Cuts and Jobs Act pulled the AMT back further. For 2018 it raised individual exemptions to $70,300 for single filers and $109,400 for married couples filing jointly.³ It also raised the phase-out thresholds — the income levels where the exemption begins shrinking — to $500,000 for single filers and $1 million for joint filers, up from roughly $120,700 and $160,900.¹⁰

The effect was dramatic. Taxpayers subject to the AMT fell from more than 5 million in 2017 to an estimated 200,000 in 2018.¹⁰ For most upper-middle-income households, the group hit hardest before 2018, the tax simply stopped applying.

TCJA also repealed the corporate alternative minimum tax that had existed since 1986. The parallel calculation profitable corporations had been running for roughly 30 years disappeared for tax years starting after 2017.

Why SALT Mattered So Much

Much of the pre-2018 AMT’s reach came from how it handled state and local taxes. The regular code allowed unlimited deductions for state income tax and local property tax. The AMT disallowed them completely. For families in high-tax states, losing that deduction alone often pushed AMT liability above the regular tax bill. TCJA’s separate $10,000 cap on state and local tax deductions under the regular code narrowed the gap between the two systems.

2022: A Different Corporate Minimum Tax Returns

Five years after TCJA scrapped the corporate AMT, Congress brought back a different version. The Inflation Reduction Act of 2022 created the Corporate Alternative Minimum Tax, a 15% minimum tax on the adjusted financial statement income of corporations with average annual income above $1 billion.¹¹ It took effect for tax years beginning after December 31, 2022.¹²

The mechanics differ from the old corporate AMT. Instead of recalculating taxable income with adjusted preferences, it starts from financial statement income, the profit figure a company reports to shareholders. The $1 billion threshold confines it to the largest corporations. The impulse behind it, though, is the same one that produced the 1969 minimum tax: public frustration that some of the most profitable entities pay little federal tax.

2025: The TCJA Rules Become Permanent

TCJA’s higher exemptions and phase-outs were scheduled to expire after 2025, which would have pushed an estimated 7 million taxpayers back into the AMT. The One Big Beautiful Bill Act, signed in 2025, made TCJA’s higher exemption amounts and phase-out thresholds permanent, with continued inflation adjustments.¹³

For 2026 the AMT exemption amounts are:

$140,200 for married couples filing jointly and surviving spouses
$90,100 for single filers
$70,100 for married individuals filing separately

The exemption begins to phase out at $1,000,000 for married couples filing jointly and $500,000 for single filers.¹³ One change worth noting: the 2025 law doubled the phase-out rate from 25 cents to 50 cents per dollar of income above the threshold, so the exemption vanishes twice as fast at very high income levels. Taxpayers below the thresholds are unaffected.

AMT income above the exemption is still taxed at the two rates set in 1993: 26% on the first portion and 28% above the crossover point.⁷

Who the AMT Reaches Now

With TCJA’s higher thresholds locked in, the individual AMT applies to roughly 200,000 taxpayers rather than the millions it was on track to swallow before 2018. The people most likely to trigger it are high-income earners who exercise large blocks of incentive stock options, hold significant private activity bond investments, or have other preference items that widen the gap between regular taxable income and AMT income. Most households that once dreaded April now sit safely below the exemption, and the tax has settled roughly back onto the group it was written for in 1969.

1
U.S. Department of the Treasury. AMT
2
GovInfo. Public Law 91-172 – Tax Reform Act of 1969
3
Congress.gov. The Alternative Minimum Tax for Individuals: In Brief
4
U.S. Government Publishing Office. Public Law 97-248 – Tax Equity and Fiscal Responsibility Act of 1982
5
Congress.gov. H.R. 3838 – Tax Reform Act of 1986
6
Joint Committee on Taxation. Present Law and Issues Relating to the Individual Alternative Minimum Tax
7
Office of the Law Revision Counsel. 26 USC 55 – Alternative Minimum Tax Imposed
8
U.S. Bureau of Economic Analysis. How Will the American Taxpayer Relief Act of 2012 Impact Personal Current Taxes?
9
Congress.gov. H.R. 8 – American Taxpayer Relief Act of 2012
10
Tax Policy Center. How Did the TCJA Change the AMT?
11
Internal Revenue Service. Corporate Alternative Minimum Tax
12
Internal Revenue Service. IRS Clarifies Rules for Corporate Alternative Minimum Tax
13
Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026, Including Amendments From the One, Big, Beautiful Bill