Alternative Minimum Tax for Business Owners: How AMT Works and When It Applies

By Yarik Yarosh, CPA ·September 5, 2026 ·6 min read

Written by Yarik Yarosh, CPA (US & Canada) September 5, 2026 · FL CPA license AC61704 · CPA Ontario

The Alternative Minimum Tax is a shadow tax system that recalculates your tax liability by adding back certain deductions and preference items, applying a flat rate (26%/28%), and comparing the result to your regular tax. If the AMT calculation produces a higher tax, you pay the difference as additional tax. Under IRC 55, the AMT is calculated by starting with regular taxable income, adding back AMT adjustments and preference items to arrive at Alternative Minimum Taxable Income (AMTI), subtracting the AMT exemption ($88,100 single / $137,000 MFJ for 2025), and applying the AMT rate (26% on the first $248,300 above the exemption, 28% on the excess). The TCJA significantly reduced the number of taxpayers affected by AMT by raising the exemption amounts and phase-out thresholds, but certain transactions (particularly ISO exercises) can still trigger substantial AMT liability. For business owners, the AMT interacts with depreciation (MACRS vs. ADS differences), state and local tax deductions (fully disallowed for AMT before TCJA, now largely irrelevant because of the SALT cap), and various business credits.

✓Key takeaway

AMT calculation structure (2025):

Step	Calculation
1	Start with regular taxable income
2	Add back AMT adjustments (state/local taxes, ISO spread, depreciation differences, etc.)
3	Add back tax preference items (private activity bond interest, etc.)
4	= Alternative Minimum Taxable Income (AMTI)
5	Subtract AMT exemption ($88,100 single / $137,000 MFJ)
6	Apply AMT rate (26% or 28%) = Tentative Minimum Tax (TMT)
7	If TMT > regular tax: AMT = TMT - regular tax
8	If TMT < regular tax: AMT = $0

AMT exemption phase-out (2025):

Filing Status	Exemption	Phase-Out Begins	Phase-Out Complete
Single	$88,100	$626,350	$978,750
MFJ	$137,000	$1,252,700	$1,800,700

The exemption phases out at 25 cents per dollar of AMTI above the threshold.

Common AMT triggers for business owners:

Item	AMT Treatment
ISO exercise spread	Added to AMTI (the largest modern AMT trigger)
State and local tax deduction	Not an AMT issue post-TCJA (already limited by SALT cap)
Private activity bond interest	Added to AMTI (tax-exempt for regular tax, taxable for AMT)
Depreciation (pre-TCJA property)	ADS depreciation used for AMT (different from MACRS for regular tax)
Net operating loss (AMT NOL)	Separate AMT NOL calculation; limited to 90% of AMTI
Long-term capital gains	Taxed at preferential rates for both regular tax and AMT, but high gains push AMTI into the exemption phase-out

When does AMT hit business owners?

Hypothetical example

Round numbers. A business owner (single) has $400,000 in regular taxable income and exercises ISOs with a $200,000 spread.

Regular tax calculation:

Item	Amount
Regular taxable income	$400,000
Regular tax (37% bracket)	~$105,000

AMT calculation:

Item	Amount
Regular taxable income	$400,000
Add: ISO spread (AMT preference)	$200,000
AMTI	$600,000
AMT exemption ($88,100, partially phased out)	$88,100 (phase-out doesn’t begin until $626,350 for single)
AMTI minus exemption	$511,900
TMT: first $248,300 at 26%	$64,558
TMT: remaining $263,600 at 28%	$73,808
Total TMT	$138,366
Regular tax	($105,000)
AMT liability	$33,366
Total tax (regular + AMT)	$138,366

The ISO exercise creates $33,366 in additional tax through the AMT, even though no regular income tax was triggered at exercise.

AMT credit carryforward: The AMT paid on “deferral” items (like ISO exercises, where the income isn’t permanently excluded but only deferred) generates a Minimum Tax Credit (MTC) that can be used against regular tax in future years.

Year	AMT Paid	MTC Available	How Used
2025 (exercise year)	$33,366	$33,366	Cannot use (TMT > regular tax)
2026 (if no AMT items)	$0	$33,366	Used against regular tax exceeding TMT
How long carried	Indefinitely	Until used

When the ISO stock is eventually sold:

If qualifying disposition: all gain is long-term capital gain (regular tax); the AMT basis is higher (includes the spread), so AMT gain is lower; the MTC offsets the difference
If disqualifying disposition: spread is ordinary income for regular tax (AMT and regular tax converge); MTC may fully offset in the year of sale

Strategies to minimize AMT:

Strategy	How It Helps
Exercise ISOs in stages across multiple years	Keeps the annual AMT spread below the level that triggers AMT
Exercise and sell in the same year (disqualifying disposition)	Eliminates AMT issue entirely (treated as ordinary income for both regular and AMT)
Exercise in low-income years	Lower regular taxable income means more room before AMT triggers
Project AMT before exercising	Run the calculation before committing to an exercise amount
Use the AMT credit in subsequent years	Plan for years when regular tax exceeds TMT to recover the credit
Sell enough shares to cover the AMT bill	Exercise and sell a portion to fund the tax payment

Post-TCJA AMT landscape:

Before TCJA (2017)	After TCJA (2018-2025)
AMT exemption: $54,300 single	AMT exemption: $88,100 single (2025)
Phase-out: $120,700	Phase-out: $626,350
State/local taxes: full AMT add-back	State/local taxes: already limited by SALT cap (no AMT issue)
Many middle-income taxpayers affected	Primarily affects ISO exercisers and high-income taxpayers with preference items
Estimated 5 million taxpayers paid AMT	Estimated 200,000 taxpayers pay AMT

Corporate AMT (CAMT, for very large corporations): The Inflation Reduction Act created a new Corporate Alternative Minimum Tax for corporations with average annual adjusted financial statement income (AFSI) exceeding $1 billion:

Feature	Details
Applies to	Corporations with $1B+ average AFSI over 3 years
Rate	15% of AFSI
Regular corporate tax	21%
When CAMT applies	When 15% of AFSI exceeds regular tax
Small business impact	None (the $1B threshold eliminates virtually all small businesses)

Illustrative numbers only, not a real client and not advice for your facts.

How does the alternative minimum tax affect business owners?

The AMT is a parallel tax system that adds back certain deductions and preferences to your regular taxable income to compute alternative minimum taxable income (AMTI). Common AMT triggers for business owners include the exercise of incentive stock options (ISOs), accelerated depreciation timing differences, and large state and local tax deductions. The AMT exemption amount ($85,700 for single filers, $133,300 for married filing jointly in 2024) phases out at 25 cents per dollar of AMTI above $609,350 (single) or $1,218,700 (married filing jointly). You pay whichever is higher: your regular tax or the AMT amount (26% on the first $232,600 of AMTI above the exemption, 28% on the excess). AMT paid due to timing differences (like ISO exercises or depreciation) generates a minimum tax credit that can offset regular tax in future years when those items reverse.

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Cite this page

Yarik Yarosh, CPA. "Alternative Minimum Tax for Business Owners: How AMT Works and When It Applies." Blue Cloud CPA, September 5, 2026. https://bluecloudcpa.com/guides/small-business-alternative-minimum-tax-amt-business-owners

This guide is general information, not tax advice for your specific situation. Which points apply, and how, depends on your facts.

Alternative Minimum Tax for Business Owners: How AMT Works and When It Applies

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