Incentive stock options have a favourable structure: no regular income tax at exercise, and if you hold long enough, the entire gain is taxed as long-term capital gain rather than as ordinary income. That is genuinely valuable.
The alternative minimum tax is the catch. For that parallel calculation, the difference between the exercise price and the fair value at exercise counts as income — even though you sold nothing and received no cash.
This is general information, not tax advice. This is a complex area where mistakes are expensive; work with a qualified professional.
What changed in 2026
- Exemption levels stayed elevated. With alternative minimum tax exemptions at higher permanent levels, fewer people are caught, and those with large exercises still are.
- Secondary market liquidity improved unevenly. More private company employees had some path to selling, though frequently restricted and not guaranteed.
- Modelling tools spread. Software calculating the exposure before exercising became more accessible, which is the main defence.
- The trap kept catching people. Employees exercising large positions in illiquid private companies remained the recurring hard case.
Why the trap is so damaging
| Situation |
Outcome |
| Exercise, stock is liquid, sell some |
Sell enough to cover the tax; manageable |
| Exercise, stock is illiquid, value holds |
Real cash tax bill, no way to sell shares to pay it |
| Exercise, stock is illiquid, value collapses |
Tax owed on a paper gain that no longer exists |
| Exercise early when the spread is minimal |
Little or no exposure |
| Exercise and sell in the same year |
Becomes a disqualifying disposition; ordinary income instead |
The third row is the scenario that has ruined people. Exercise in a year when the company is highly valued, incur a large alternative minimum tax liability based on that valuation, and then watch the company's value collapse. The tax is owed on the value at exercise. The shares are worth little or nothing. There is no mechanism that undoes it.
That is not a hypothetical; it happened at scale after previous market downturns.
Exercising without the trap
Exercise early, while the spread is small. The exposure is generated by the difference between strike price and fair value. Exercising shortly after grant, when they are close, produces little or no alternative minimum tax income. This is the single most effective approach and it requires cash and conviction early.
Model before exercising. Calculate the alternative minimum tax exposure for the specific number of shares before doing anything. This is arithmetic, not a guess, and doing it takes an hour.
Exercise up to your threshold. There is typically a quantity you can exercise each year without triggering additional tax. Exercising to that point annually, over several years, spreads the position without the bill.
Consider the disqualifying disposition. Exercising and selling in the same year forfeits the favourable treatment and converts the gain to ordinary income — and it also removes the alternative minimum tax problem, and it produces cash. For a liquid stock that is sometimes the right trade.
Do not exercise illiquid stock at a high valuation without a plan for the tax. If you cannot sell shares to pay the bill, you need the cash from somewhere else, and you are taking real risk on the company's future value.
The credit mechanism recovers some of it eventually — alternative minimum tax paid generates a credit usable against future regular tax — over years, and only if you have future tax liability to apply it against.
Common mistakes
- Exercising without modelling the exposure. The arithmetic is knowable in advance.
- Large exercises of illiquid stock at peak valuations. The devastating case.
- Assuming no sale means no tax. The parallel calculation does not care.
- Missing the annual threshold strategy. Spreading exercises avoids the bill entirely for many.
- Forgetting the holding period requirements. Selling too early converts to ordinary income.
- Ignoring the credit. Recoverable over time, and easy to forget to claim.
FAQ
How do I know my exposure before exercising?
Calculate the spread times the number of shares, then run the alternative minimum tax calculation for your full situation. Software and tax professionals both do this.
What if the company is private and there is no fair value?
The most recent valuation is typically used. This is exactly the illiquid scenario that carries the most risk.
Can I undo an exercise?
Generally not. Some plans permit a rescission within a narrow window in the same tax year; do not count on it.
Do non-qualified options have this problem?
No. They generate ordinary income at exercise with withholding, which is more tax but far more predictable.
Where to go next
For other equity types, read RSU vesting tax and ESPP discount explained. For early-stage shares, 83(b) election explained, and for the gain exclusion, QSBS explained.