Understanding the IRS Alternative Minimum Tax (AMT) in 2026

What AMT Is — The Parallel Tax System

The Alternative Minimum Tax was created to ensure that high-income taxpayers could not use deductions, credits, and preferences to reduce their regular income tax to zero or near-zero.

The AMT operates as a parallel calculation: (1) calculate regular tax in the ordinary way; (2) calculate AMT separately — starting from a broader income base that adds back certain "preference items"; (3) pay whichever is higher. AMT only applies when the AMT calculation produces a result higher than regular tax (IRC §55).

The AMT Formula

Step 1: Start with regular taxable income (from Form 1040)
Step 2: Add back AMT adjustments and preferences:
  + Standard deduction if claimed (Form 6251, line 2a)
  + State/local taxes deducted for regular tax, if applicable
  + ISO bargain element (FMV minus exercise price)
  + Other AMT adjustments as applicable
  = Alternative Minimum Taxable Income (AMTI)

Step 3: Subtract REDUCED 2026 AMT exemption
  Single: max(0, $90,100 − 50% × max(0, AMTI − $500,000))
  MFJ: max(0, $140,200 − 50% × max(0, AMTI − $1,000,000))
  MFS: max(0, $70,100 − 50% × max(0, AMTI − $500,000))
  Taxable excess = max(0, AMTI − reduced exemption)

Step 4: Apply rates to taxable excess
  26% on first $244,500 ($122,250 if MFS)
  28% above the applicable breakpoint
  = Tentative Minimum Tax (TMT), before applicable credits

Step 5: Compare
  If TMT > regular tax → additional AMT equals the excess
  If regular tax ≥ TMT → no additional AMT due

Source: IRC §§55–56; Rev. Proc. 2025-32 §4.10; Form 6251 instructions (standard-deduction addback).

Common AMT Triggers Post-TCJA

TCJA dramatically curtailed the AMT's reach by raising the exemption substantially and increasing phase-out thresholds. For most filers, SALT and miscellaneous itemized deductions are no longer meaningful AMT triggers.

1. Incentive Stock Option (ISO) exercises:This is the dominant AMT trigger for working professionals today. When you exercise an ISO, you don't pay regular income tax at exercise. However, the "bargain element" — the difference between the fair market value (FMV) and your exercise price — is treated as an AMT preference item and added to AMTI. A large bargain element can create a massive AMT bill even for someone with modest regular income.

2. Accelerated depreciation: Businesses and landlords who use accelerated depreciation methods (MACRS, bonus depreciation) must use a slower schedule for AMT purposes, creating an add-back.

3. Certain tax-exempt income: Some private activity bond interest that is tax-exempt for regular purposes is an AMT preference item.

2026 AMT Exemption and Phase-Out Thresholds

Per Rev. Proc. 2025-32 §4.10:

Phase-out mechanics: The exemption falls $0.50 for each dollar of AMTI above the phase-out threshold, but not below zero. A single filer with $600,000 AMTI is $100,000 over the $500,000 threshold, reducing the $90,100 exemption by $50,000 to $40,100. The single exemption reaches zero at $680,200 AMTI; the MFJ exemption reaches zero at $1,280,400.

Worked Example — California ISO Holder

Profile: Single filer. W-2 wages: $200,000. Exercised 10,000 ISO shares at $10 strike price when FMV was $100. Bargain element: ($100 − $10) × 10,000 = $900,000.

Regular tax calculation (2026 single brackets; no credits):
W-2 wages: $200,000
Standard deduction: $16,100
Taxable income: $183,900
Regular income tax: $17,966 + 24% × ($183,900 − $105,700) = $36,734

AMT calculation:
Regular taxable income: $183,900
Add back: standard deduction (not allowed for AMT): $16,100
Add: ISO bargain element ($90 × 10,000): $900,000
AMTI: $1,100,000

AMT exemption (single): $90,100 before phase-out
Phase-out excess: $1,100,000 − $500,000 = $600,000
Exemption reduction: 50% × $600,000 = $300,000
Reduced exemption: max($0, $90,100 − $300,000) = $0
AMT taxable excess: $1,100,000

AMT tax (no preferential-rate gains or foreign tax credit):
26% on $244,500 = $63,570
28% on ($1,100,000 − $244,500) = 28% × $855,500 = $239,540
Total Tentative Minimum Tax (TMT): $303,110

Additional AMT: $303,110 − $36,734 = $266,376

Result: $266,376 additional AMT on top of regular tax. Total federal income tax in this simplified no-credit example: $303,110.

Strategies — Managing ISO Exercise AMT

1. Exercise in low-AMT years. Spread ISO exercises across multiple years. Model the AMT breakeven before exercising — exercise enough shares that the bargain element stays below the AMT exposure zone.

2. Early exercise (83(b) election). For early-stage startups with low FMV, exercising immediately after grant (when FMV ≈ strike price) minimizes or eliminates the bargain element. This requires filing an 83(b) election within 30 days of exercise.

3. Track the AMT credit carryforward. When you pay AMT due to an ISO exercise and later sell the stock (recognizing the gain as regular income), the prior AMT may convert to an AMT credit that offsets future regular tax — see below.

4. Charitable stock donations. If you hold appreciated ISO stock (post-exercise, post-holding-period), donating it to charity avoids the capital gains tax. Complex; consult a tax professional.

The AMT Credit — Recovery in Later Years

When you pay AMT due to "deferral" preference items (like ISO bargain elements), you generate an AMT credit (Form 8801). This credit can offset regular tax in future years when your regular tax exceeds your AMT calculation.

In essence: the AMT collected on the ISO bargain element is not permanently lost. When you eventually sell the ISO stock and pay regular capital gains tax, the AMT credit offsets that regular tax liability. The AMT credit carries forward indefinitely.

Frequently Asked Questions

Estimate Your Full Federal Liability with the 2026 Federal Income Tax Calculator

AMT calculations are mechanical but detail-sensitive. The ISO bargain element, depreciation adjustments, and exemption phase-outs all interact. The 2026 federal income tax calculator includes AMT as part of the full liability estimate for filers with ISO income or other AMT-relevant inputs. The capital gains tax calculator helps model the gain side when ISO shares are eventually sold.