The U.S. tax code runs two parallel systems simultaneously. Every year you calculate both, and pay whichever is higher. Here's how they differ.

High Level Differences

| General Category | Regular Income Tax | Alternative Minimum Tax | |---|---|---| | Marginal Tax Brackets | 7 brackets ranging from 0%–37% | 2 brackets: 26% and 28% | | Adjustments & Deductions | Standard deduction or itemized deductions (mortgage interest, SALT, etc.) | Only a smaller subset of specific deductions. No standard deduction. | | Exemptions | None (removed by TCJA 2017) | Large AMT-specific exemption based on filing status and income |

2026 Regular Income Tax Brackets

Single filers — taxable income over:

| Rate | Income Threshold | |---|---| | 10% | $0 | | 12% | $12,400 | | 22% | $49,750 | | 24% | $106,000 | | 32% | $202,350 | | 35% | $257,350 | | 37% | $640,600 |

Married filing jointly — taxable income over:

| Rate | Income Threshold | |---|---| | 10% | $0 | | 12% | $24,800 | | 22% | $99,500 | | 24% | $211,400 | | 32% | $404,700 | | 35% | $514,700 | | 37% | $768,600 |

2026 AMT brackets (all filers except married separately):

| Rate | Income Threshold | |---|---| | 26% | $0 | | 28% | $244,500 |

AMT is one of the rare instances where being married may work against you. The 28% bracket threshold is the same for single filers and married couples filing jointly — $244,500.

Deductions

Above-the-line deductions (apply to both systems):

| Deduction | 2026 Limit | Regular Tax | AMT | |---|---|---|---| | Traditional 401(k) | $23,500 | ✓ | ✓ | | HSA | $4,400 (self) / $8,750 (family) | ✓ | ✓ | | Traditional IRA | $7,000 | ✓ | ✓ | | Student Loan Interest | $2,500 | ✓ | ✓ |

Below-the-line deductions:

| Deduction | Regular Tax | AMT | |---|---|---| | Standard Deduction ($16,100 single / $32,200 MFJ in 2026) | ✓ | ✗ | | Mortgage Interest | ✓ | ✓ | | SALT (capped at $40,400 in 2026 per OBBBA) | ✓ | ✗ | | Medical Expenses | ✓ | ✗ |

Note: The SALT cap was raised significantly in 2026 under the One Big Beautiful Bill Act (OBBBA) — up from $10,000 previously. It phases out for high earners above roughly $505,000 MAGI.

2026 AMT Exemptions

| Filing Status | AMT Exemption | Phaseout Threshold | |---|---|---| | Single | $90,100 | $500,000 | | Married Filing Jointly | $140,200 | $1,000,000 | | Married Filing Separately | $70,100 | $500,000 | | Head of Household | $90,100 | $500,000 |

Important 2026 change: The phaseout rate doubled from 0.25 to 0.50 under OBBBA. This means for every $1 of AMTI over the threshold, your exemption shrinks by $0.50 — twice as fast as in prior years. High earners lose their exemption much more quickly now.

How the exemption works:

  1. If your AMTI is below the exemption amount, you owe no AMT.
  2. If your AMTI is above the exemption, you subtract the exemption to arrive at your final taxable AMTI.
  3. If your AMTI exceeds the phaseout threshold, the exemption shrinks by $0.50 per $1 over the threshold until it's fully phased out.

Example (2026, single filer): AMTI of $510,000 — $10,000 over the $500,000 threshold. At a 0.50 phaseout rate, the exemption is reduced by $5,000 (50% × $10,000), leaving a $85,100 exemption instead of $90,100.

Next: see how the AMT is actually calculated with a step-by-step example →