Short answer: To recover an AMT credit created by exercising ISOs, you need a year in which your regular tax is higher than your tentative minimum tax. Selling the shares in a qualifying disposition does that, because your AMT basis is higher than your regular-tax basis, so the sale produces less AMT gain than regular gain. In our example ($10 strike, $50 value at exercise, $100 sale), that is $40 per share. A sale is not free: it creates a taxable gain, and it may not release the whole credit in one year.
How do you recover an AMT credit after exercising ISOs?
If you exercised incentive stock options, paid AMT and have held the shares since, the credit does not come back on a schedule just because time passes. Section 53(c) lets you use the credit only up to the amount by which regular tax exceeds tentative minimum tax (TMT), and the credit is not refundable. Holding the stock changes neither number. A qualifying sale does: it produces more regular-tax gain than AMT gain, because your AMT basis is higher than your regular-tax basis, and that opens the gap the credit needs.
A sale is the most direct lever available, but it is not free. It creates a taxable gain, and how much credit it releases depends on the whole return. For many people who exercised on the way out of a company, the sequence is: satisfy the holding periods, sell, use the credit, then decide whether to buy shares back. Those holders often also have RSUs or other equity in the same company, so selling the ISO shares reduces a concentration they would otherwise keep.
What happens to AMTI in the year you exercise?
Assume a $10 strike price and a $50 fair market value on the date the shares become transferable or are no longer subject to a substantial risk of forfeiture. For a valid ISO, §421(a) means no regular-tax income at exercise. For AMT, §56(b)(3) turns off §421, so the $40 spread is an adjustment that increases AMTI, and the AMT basis rises from $10 to $50.
| Regular taxable income from exercise | $0 |
| AMT adjustment ($50 FMV − $10 strike) | +$40 |
| Gap: regular income − AMTI | −$40 |
Exercise year, per share. The AMT you pay on the $40 is what becomes the minimum tax credit under §53(b). Section 53(d) excludes only specified adjustments and preferences from the credit base, and the ISO adjustment is not one of them.
Why doesn’t holding the shares recover the credit?
Section 53(c) caps the credit at regular tax (reduced by specified other credits) minus TMT for the year. A large regular tax bill is not enough by itself: if TMT is also large, there is still no capacity. While you hold the shares, nothing about the position moves regular tax up or TMT down. Recovery needs a year in which regular tax exceeds TMT, and a qualifying sale is an event that creates that year on purpose. If your regular tax already exceeds TMT in a normal year, some credit may release without a sale. Holding just doesn’t create that room.
What happens in the year you sell the shares?
A disposition is qualifying under §422(a)(1) if you sell more than two years after the grant and more than one year after the shares were transferred on exercise. Sell at $100 and the two systems measure the gain differently.
| Regular tax | AMT | |
|---|---|---|
| Basis per share | $10 | $50 |
| Sale price per share | $100 | $100 |
| Gain per share | $90 capital gain | $50 capital gain |
| Form 6251, line 2k | — | −$40 |
The regular-tax gain is $90 of capital gain, long-term if you held more than a year. It includes the $40 exercise-date spread and the $50 of appreciation since. The AMT gain is $50 because the AMT basis is $50. The $40 difference is reported as a negative adjustment on Form 6251, line 2k. It is not a second ordinary-income item and it is not converted into capital gain. It is a basis difference.
| Regular-tax gain ($100 − $10 basis) | $90 |
| AMT gain ($100 − $50 basis) | $50 |
| Form 6251 line 2k adjustment | −$40 |
Sale year, per share. Regular tax uses the $10 basis and AMT uses the $50 basis, so AMTI falls $40 relative to regular income.
| Exercise year: regular − AMTI | −$40 |
| Sale year: regular − AMTI | +$40 |
| Swing between the two years | $80 |
The gap between regular income and AMTI is negative $40 in the exercise year and positive $40 in the sale year. The income gap shows direction. Credit capacity is measured in tax dollars: regular tax minus TMT.
| Exercise year | Sale year (qualifying) | |
|---|---|---|
| Regular-tax income from the shares | $0 | $90 capital gain |
| AMT income from the shares | $40 ISO adjustment | $50 capital gain |
| Regular income minus AMTI | −$40 | +$40 |
| Credit effect | AMT paid creates the credit | Gap lets §53(c) release credit |
In the exercise year AMTI exceeds regular income by $40, which is why AMT is owed. In the sale year regular income exceeds AMTI by $40, which is why §53(c) has room to release credit. The sale widens the gap in the direction the credit needs.
How much of the credit does a sale recover?
The credit is a tax amount, not an income amount. The usable credit is not necessarily the ISO adjustment multiplied by 26% or 28%, and AMT does not tax capital gain at a flat 26% or 28%, because Form 6251 applies capital gain rates inside the TMT computation under §55(b)(3). The practical result is that a credit created at ordinary AMT rates may be recovered through a gap that sits in capital gain computations taxed at lower rates. A simplified illustration for 1,000 shares, using federal tax only and assuming regular tax and TMT on the rest of the return are equal:
- Exercise year: $40,000 of AMTI at 28% creates up to $11,200 of AMT, and so up to $11,200 of credit.
- Sale year, regular tax: $90,000 of long-term capital gain at 20% is $18,000.
- Sale year, TMT: $50,000 of capital gain at 20% is $10,000.
- Gap: $8,000, so up to $8,000 of credit is usable in the sale year and about $3,200 carries forward.
| AMT created at exercise (up to, 28%) | $11,200 |
| Credit usable in the sale year (20% gap) | $8,000 |
| Credit still carried forward | $3,200 |
Illustrative only. At a 15% capital gain rate the sale-year gap would be $6,000.
A sale can release most of the credit in one year, but it should not be assumed to release all of it, and you pay real regular tax on a $90,000 gain to get there. The 3.8% net investment income tax, if it applies, adds about $3,420 on that gain, and the credit generally can’t offset it. The comparison that matters is the additional regular tax, the reduction in TMT and the resulting §53(c) capacity, not the size of the carryforward alone.
Why are ISO shares better to sell than other stock?
You might wonder whether selling other stock would speed recovery. Stock with the same basis for regular tax and AMT produces the same gain in both computations and no Form 6251 disposition adjustment. It raises regular tax and TMT by similar amounts, so it may add little capacity and could reduce it if TMT rises more. ISO shares carry a built-in basis difference, which is what makes the sale-year gap predictable. The same test applies to recognizing other income: it helps only to the extent it raises regular tax by more than it raises TMT.
Should you buy the shares back after selling?
Once the credit is used there are two reasonable paths, and the choice depends on your concentration more than on the tax rules.
- Stay diversified. If you also hold RSUs or other equity in the same company, the sale reduces a concentration you already carry. Reinvest the proceeds elsewhere.
- Buy the shares back. If you want the exposure and the stock trades on a public market, you can repurchase it. Your new basis is the purchase price for both regular tax and AMT, so the basis difference you had to track ends with the sale.
The 30-day wait people associate with wash sales is a loss rule. Section 1091 disallows a loss when you acquire substantially identical stock within 30 days before or after the sale. In this example the sale is a gain for both regular tax and AMT, so there is no loss to disallow and a same-day repurchase does not trigger the rule. Waiting 30 days matters only if the price falls below a basis. A sale between $10 and $50 produces a regular-tax gain but an AMT loss, and whether §1091 also disallows that AMT loss is worth confirming with your preparer. RSU vests and ESPP purchases inside the 30-day window count as acquisitions. Waiting also means carrying the market risk of being out of the stock, so it is a cost, not a free precaution.
What should you check before selling?
- Holding period. A sale before the later of two years from grant and one year from exercise is a disqualifying disposition. The exercise-date spread, limited to the total gain, becomes ordinary compensation income in the sale year, and the calculation differs. Model it separately.
- Same-year sale. Selling in the year of exercise generally avoids the ISO adjustment, so it ordinarily creates no AMT credit.
- Do not stack exercises. Exercising more ISOs while a credit is unused adds a new AMT adjustment and can create more credit instead of using the existing one.
- Two basis records. Track regular-tax basis and AMT basis for each lot. The difference drives the sale-year calculation.
- The credit is personal. In Vichich v. Commissioner, 146 T.C. No. 12 (2016), the Tax Court did not let a surviving spouse use her deceased husband’s credit from ISO exercises that predated their marriage.
- Exemption phaseout. Beginning in 2026 the AMT exemption phases out starting at $500,000 of AMTI for single filers and $1,000,000 for joint filers, at 50 cents per dollar. A large sale year can shrink the exemption and raise TMT.
- Liquidity. The strategy assumes you can sell. Private-company shares, lockups and trading windows can prevent it.
- Inputs to model. Credit carryforward (Form 8801), regular tax, TMT, other credits, exercise-date spread, AMT basis, sale date and price, holding periods and filing status.
What is the bottom line?
For someone holding ISO shares with an unused AMT credit, a qualifying sale is usually the most direct way to use it, because the higher AMT basis lowers TMT relative to regular tax in the sale year. Run the numbers first, since the credit released depends on the full return. After that, decide on diversification before deciding on a repurchase.
To estimate the AMT and the credit from your own ISO exercise, try our ISO AMT calculator.
Sources
- 26 U.S.C. §53, Credit for prior year minimum tax liability
- 26 U.S.C. §55, Alternative minimum tax imposed
- 26 U.S.C. §56, Adjustments in computing alternative minimum taxable income
- 26 U.S.C. §421, General rules (statutory stock options)
- 26 U.S.C. §422, Incentive stock options
- 26 U.S.C. §1(h), Maximum capital gains rate
- 26 U.S.C. §1091, Loss from wash sales of stock or securities
- Instructions for Form 6251, Alternative Minimum Tax (IRS)
- Instructions for Form 8801, Credit for Prior Year Minimum Tax (IRS)
- Publication 525, Taxable and Nontaxable Income (IRS)
- Vichich v. Commissioner, 146 T.C. No. 12 (2016) (U.S. Tax Court)
This article is for general educational purposes and is not tax advice for your specific situation. Examples are simplified, shown per share unless noted, and reflect federal rules only.