Under the Alternative Minimum Tax, long-term capital gains and qualified dividends keep their preferential rates of 0%, 15%, and 20%. The AMT does not reclassify those gains as ordinary income or push them into its 26% and 28% brackets. Instead, the two systems layer together through a stacking calculation on Form 6251 that applies the preferential rate to each dollar of gain based on your total Alternative Minimum Taxable Income. Gains can still raise your AMTI enough to trigger AMT indirectly, and a few related items — incentive stock options, older qualified small business stock, and private activity bond interest — carry their own complications.
How Long-Term Gains Are Taxed Inside the AMT
If you hold an asset more than a year and sell at a gain, the AMT uses the same preferential rate breakpoints as the regular tax. For 2026, single filers pay 0% on taxable income up to $49,450, 15% from $49,450 to $545,500, and 20% above $545,500. For married couples filing jointly, the 15% bracket runs from $98,900 to $613,700, with the 20% rate applying above $613,700. Under the AMT, those same breakpoints are measured against your AMTI rather than regular taxable income.1Internal Revenue Service. Topic No. 556, Alternative Minimum Tax
The 26% and 28% AMT rates apply only to the ordinary income portion of your AMTI. For 2026, the 26% rate covers the first $244,500 of taxable excess above the exemption, and 28% applies above that. Married individuals filing separately use half those brackets.2Office of the Law Revision Counsel. 26 USC 55 – Alternative Minimum Tax Imposed
The Stacking Calculation on Form 6251
Capital gains sit on top of your ordinary AMTI, not alongside it. The IRS layers the two in Part III of Form 6251: ordinary AMTI is taxed first at the AMT rates, and the net capital gain stacks above it. The rate the gain receives depends on where your ordinary income ran out relative to the capital gains breakpoints.3Internal Revenue Service. Instructions for Form 6251
A single filer with $400,000 of ordinary AMTI and $200,000 of long-term capital gains illustrates the mechanic. The 20% threshold for a single filer is $545,500. The ordinary income fills the space below that line, so the first $145,500 of gain lands in the 15% bracket and the remaining $54,500 falls into the 20% bracket. The ordinary income portion is taxed separately at the AMT rates.
The IRS directs you through either the AMT Qualified Dividends and Capital Gain Tax Worksheet or the AMT Schedule D Tax Worksheet, with the result feeding into Part III of Form 6251.
Short-Term Gains Get No Protection
Assets held one year or less produce short-term capital gains, which are ordinary income for both regular tax and AMT. They face the full 26% or 28% AMT rate after your exemption is applied, with no preferential treatment.3Internal Revenue Service. Instructions for Form 6251
What Actually Pushes Capital Gains Investors Into AMT
Capital gains by themselves rarely cause AMT, because they’re taxed the same way under both systems. AMT appears when adjustments and preference items widen the gap between regular tax and tentative minimum tax. Large realized gains then amplify that gap by raising AMTI and pushing the gains themselves into higher preferential brackets.
State and Local Tax Deductions
The regular tax system allows a SALT deduction up to a cap raised to $40,000 for tax years 2025 through 2029 by the One, Big, Beautiful Bill, with a phaseout for household incomes above $500,000.4Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 The AMT disallows SALT entirely. State income tax, local tax, and property tax all get added back when you compute AMTI. For a resident of a high-tax state who also realized a large gain, that add-back alone can lift AMTI far enough to generate AMT and push more of the gain into the 20% bracket.
Incentive Stock Options
Exercising an ISO and holding the stock produces no regular tax that year, but the bargain element — the spread between exercise price and fair market value on the exercise date — is added to AMTI as an adjustment.3Internal Revenue Service. Instructions for Form 6251 A $20,000 exercise on stock worth $200,000 adds $180,000 to AMTI on paper gains you haven’t sold. This is a timing difference. Your AMT basis in the stock becomes higher than your regular tax basis, so the AMT gain at sale will be smaller, and the AMT you paid generates a Minimum Tax Credit against future regular tax.
Private Activity Bond Interest
Interest from private activity bonds issued after August 7, 1986, is excluded from regular taxable income but included in AMTI as a preference item. Municipal bond fund investors can be affected indirectly, because a portion of exempt-interest dividends may be attributable to these bonds.3Internal Revenue Service. Instructions for Form 6251
Depreciation Differences
Rental property and other depreciable business assets can produce a smaller depreciation deduction under AMT than under the regular tax. The AMT requires the 150% declining balance method for certain property, and the difference against more accelerated regular-tax methods is added back to AMTI.5Office of the Law Revision Counsel. 26 USC 56 – Adjustments in Computing Alternative Minimum Taxable Income
Separate Capital Loss Carryovers
Because cost basis can differ between the two systems — most often after an ISO exercise — the gain or loss on a sale may be different under each calculation. If your refigured AMT Schedule D produces a capital loss, the carryover amount can differ from your regular tax carryover.6Internal Revenue Service. Instructions for Form 6251 – Alternative Minimum Tax – Individuals
The IRS provides a separate AMT Capital Loss Carryover Worksheet in the Schedule D instructions. Running one set of numbers and assuming they apply to both systems is a common error, and it compounds year over year if left uncorrected.
Qualified Small Business Stock
Section 1202 lets you exclude gain on the sale of qualified small business stock held more than five years. For QSBS acquired after September 27, 2010, the full 100% exclusion applies, and none of the excluded gain is treated as an AMT preference. You pay nothing on qualifying gains under either system.
Older QSBS is treated differently. Stock issued before September 28, 2010, qualifies for only a 50% or 75% exclusion depending on acquisition date, and the excluded portion is a preference item for AMT. The gain you excluded on your regular return gets added into AMTI, potentially producing AMT on income you considered tax-free.
This exclusion is permanent in character, not a timing difference. AMT paid because of the Section 1202 preference does not generate a Minimum Tax Credit you can recover later.7Internal Revenue Service. 2025 Instructions for Form 8801
The 3.8% Net Investment Income Tax
The AMT is not the only extra layer on capital gains. The Net Investment Income Tax adds 3.8% when modified adjusted gross income exceeds $200,000 for single filers or $250,000 for joint filers. The NIIT is computed separately from both the regular tax and the AMT; it sits on top of whichever system produces your liability.8Internal Revenue Service. Topic No. 559, Net Investment Income Tax
A high-income taxpayer in the 20% bracket who is also subject to the NIIT pays an effective 23.8% federal rate on long-term gains before any state tax. The NIIT thresholds are not indexed for inflation, so they catch more filers each year. A projection for a large sale or ISO exercise that leaves the NIIT out will undercount the real cost.
The Minimum Tax Credit
AMT paid because of timing differences is recoverable. The Minimum Tax Credit tracks AMT attributable to deferral items and lets you apply it against regular tax in any later year when regular tax exceeds tentative minimum tax, down to (but not below) the tentative minimum tax amount.7Internal Revenue Service. 2025 Instructions for Form 8801 The credit carries forward indefinitely and is claimed on Form 8801.
Only deferral items qualify. The ISO bargain element and depreciation differences generate credit because they reverse later. Exclusion items — SALT disallowance, the standard deduction add-back, private activity bond interest, and the Section 1202 preference — produce a permanent gap between the two systems, and AMT paid on their account does not create a credit.7Internal Revenue Service. 2025 Instructions for Form 8801
For ISO exercisers who paid a large AMT bill, the credit is where the math eventually balances. At sale, AMT basis is higher than regular tax basis, so the AMT gain is smaller and regular tax typically exceeds tentative minimum tax, opening room to apply the accumulated credit. Tracking both bases in the shares from exercise through sale is what makes the credit calculable.