An AMT capital loss carryover is the portion of your net investment loss, figured under Alternative Minimum Tax rules, that exceeds the $3,000 annual deduction limit and rolls forward to future tax years. It sits alongside your regular tax capital loss carryover as a separate number, and the two rarely match. The difference comes from cost basis: certain assets, especially stock acquired through incentive stock options, have a higher basis for AMT purposes than for regular tax, so the loss you realize on sale is larger under the AMT calculation.
Why the AMT Number Differs From Your Regular Number
The AMT is a parallel tax calculation. You figure your liability both ways, and if the AMT result exceeds your regular tax, you pay the difference on top of your normal bill. The AMT begins with your regular taxable income and then adds back or adjusts certain items to reach alternative minimum taxable income (AMTI).1Office of the Law Revision Counsel. 26 USC 55 – Alternative Minimum Tax Imposed Some of those adjustments change the cost basis of assets you hold, so the gain or loss you realize when you eventually sell can be a completely different number under each system.
For most individual taxpayers, the biggest source of divergence is incentive stock options (ISOs). When you exercise an ISO and hold the shares, regular tax ignores the spread between the exercise price and the stock’s market value on the exercise date. The AMT treats that spread as income in the year you exercise.2Office of the Law Revision Counsel. 26 USC 56 – Adjustments in Computing Alternative Minimum Taxable Income Recognizing that income gives you a higher basis in the stock for AMT purposes. If the stock later falls and you sell at a loss, your AMT loss is bigger than your regular loss because you started from that higher basis. That mismatch is what creates a separate AMT capital loss carryover.
Depreciation differences can also create diverging carryovers. The AMT historically required slower depreciation methods for certain tangible property, producing a different adjusted basis over time.2Office of the Law Revision Counsel. 26 USC 56 – Adjustments in Computing Alternative Minimum Taxable Income When that property is sold, the AMT gain or loss will not match the regular figure. For most individuals dealing with stock-based compensation, though, ISOs are where the split usually shows up.
Calculating the Loss
Figuring the AMT capital loss on any single disposition starts with the correct AMT basis. That basis is what you originally paid, adjusted for AMT-specific treatment during the holding period. For ISO stock, it includes the bargain element you already recognized as AMT income at exercise. For depreciable property, it reflects the AMT depreciation schedule rather than the regular one.
You report these adjustments on Form 6251, Alternative Minimum Tax—Individuals.3Internal Revenue Service. About Form 6251, Alternative Minimum Tax – Individuals Line 2k captures the difference between your regular tax gain or loss and your AMT gain or loss from property dispositions, including any capital loss carryover that differs between the two systems.4Internal Revenue Service. Instructions for Form 6251 (2025) Subtract the AMT basis from the sale proceeds and you have your AMT capital gain or loss for the year.
To determine what carries forward, the Form 6251 instructions direct you to a separate AMT Capital Loss Carryover Worksheet inside the Schedule D instructions.5Internal Revenue Service. Instructions for Form 6251 (2025) The worksheet runs the same mechanics as the regular Schedule D carryover calculation but uses your AMT figures. The result is the dollar amount of AMT capital loss you carry into next year. Getting this right requires records from the year you acquired the asset: ISO exercise confirmations, depreciation schedules, and every prior Form 6251 you filed. Reconstructing an AMT basis a decade later is difficult if those records are gone.
The $3,000 Cap Applies Separately
Capital losses first offset capital gains dollar for dollar. If your AMT capital losses exceed your AMT capital gains for the year, you can deduct up to $3,000 of the net loss against ordinary income like wages or interest. Married taxpayers filing separately are limited to $1,500 each.6Office of the Law Revision Counsel. 26 USC 1211 – Limitation on Capital Losses That amount is fixed by statute and has never been indexed for inflation.
The cap operates independently under each system. Your regular tax carryover consumes up to $3,000 against regular taxable income, and your AMT carryover separately consumes up to $3,000 against AMTI. Because the two balances are usually different, the amounts deducted in any given year will not match either.
How the Carryover Moves Forward
Any net AMT capital loss above the $3,000 annual limit carries forward under the same rules that apply to regular tax carryovers.7Office of the Law Revision Counsel. 26 USC 1212 – Capital Loss Carrybacks and Carryovers There is no expiration for individuals. A loss generated in 2026 can carry to 2027, 2028, and every year after until it is fully used. Short-term losses stay short-term and long-term losses stay long-term when they carry forward, which matters because short-term losses offset short-term gains first and long-term losses offset long-term gains first.
Each year, the leftover balance goes back into the AMT Capital Loss Carryover Worksheet in the Schedule D instructions using AMT-specific numbers, and the worksheet determines how much you can use. Meanwhile, your regular tax carryover follows its own parallel path. The two amounts may converge or diverge further depending on what happens in your account.
A continuous trail of returns and worksheets is the only reliable way to hold onto these figures over time. If you skip a year or lose a return, reconstructing the correct AMT carryover balance can send you all the way back to the year the loss originated. That is especially painful for ISO-related losses, where the AMT basis depends on stock price data from an exercise date that might be many years old.
The Related Minimum Tax Credit
Paying AMT because of an ISO exercise does not mean that tax is gone forever. The minimum tax credit under Section 53 lets you recover AMT caused by “deferral items,” which are timing differences that eventually reverse, like the ISO spread that becomes basis when you later sell the stock.8Office of the Law Revision Counsel. 26 USC 53 – Credit for Prior Year Minimum Tax Liability The credit does not apply to AMT caused by “exclusion items” such as the state and local tax add-back, which represent permanent rather than timing differences.
You claim the credit on Form 8801, Credit for Prior Year Minimum Tax. The form calculates how much of your past AMT was attributable to deferral items and determines the credit available against your current year’s regular tax liability.9Internal Revenue Service. Instructions for Form 8801 (2025) The credit carries forward indefinitely until fully used, and in a year where your regular tax exceeds your tentative minimum tax, you can apply it to reduce what you owe.
The credit and the AMT capital loss carryover solve different problems. The carryover reduces future capital gains and up to $3,000 of ordinary income per year. The credit directly reduces your tax bill dollar for dollar, but only to the extent your regular tax exceeds your tentative minimum tax. Someone who exercised ISOs in a year the stock later crashed often has both running at the same time.
What Happens at Death or Divorce
Death
An individual’s capital loss carryover, both regular and AMT, dies with the taxpayer. Unused carryovers cannot transfer to a surviving spouse or anyone else. The carryover can be applied on the decedent’s final return (which may be a joint return with the surviving spouse for that final year), but any remaining balance is permanently lost after that. When a married couple generated the carryover on joint returns, only the decedent’s portion disappears; the surviving spouse keeps their own share. Sorting out which spouse generated which portion of a joint-return loss requires going back through the transaction records.
Estates and trusts follow a different rule. When an estate or trust terminates while still holding unused capital loss carryovers, those losses pass through to the beneficiaries who inherit the property. The carryover keeps its character in the beneficiary’s hands and is taken into account for both regular tax and AMT.10eCFR. 26 CFR 1.642(h)-1 – Unused Loss Carryovers on Termination of an Estate or Trust The beneficiary first uses it in the tax year the estate or trust terminates.
Divorce and Change in Filing Status
When spouses who filed jointly switch to filing separately, whether from divorce or a change in filing choice, any capital loss carryover from the prior joint return has to be allocated between them. Treasury regulations require the allocation to follow whoever actually generated the losses. Each spouse takes the portion of the carryover attributable to their individual net capital losses from the preceding year’s joint return.11eCFR. 26 CFR 1.1212-1 – Capital Loss Carryovers and Carrybacks The same logic applies to the AMT carryover, allocated separately using each spouse’s AMT figures.
Courts have upheld this “follow the loss” approach even when divorce settlements attempted to split carryovers equally. If one spouse generated all the capital losses, that spouse takes the entire carryover no matter how other marital assets are divided.
Do You Still Need to Track This in 2026
The Tax Cuts and Jobs Act raised AMT exemption amounts sharply starting in 2018, taking millions of taxpayers out of the AMT. Those higher exemptions were made permanent by the One, Big, Beautiful Bill Act, and for 2026 the exemption is $90,100 for single filers (phasing out at $500,000 of AMTI) and $140,200 for married couples filing jointly (phasing out at $1,000,000).12Internal Revenue Service. IRS Releases Tax Inflation Adjustments for Tax Year 2026 If your AMTI stays below the exemption, you won’t owe AMT and the carryover has no immediate effect on your bill.
AMT capital loss carryovers don’t expire, though, and situations change. Someone not subject to AMT in 2026 could easily be in 2030 after a large ISO exercise or an income spike that pushes them past the phase-out. Keep tracking the carryover even in years it does nothing for you. Dropping the records because the AMT does not bite this year means losing the benefit permanently if it bites later.