Early exercise, 83(b), and AMT — the option decision you can't undo
Exercising options before a liquidity event can turn future ordinary income into capital gains and start valuable clocks early. It can also mean writing a check for tax on shares that never become worth anything. Here's the real trade-off, the 30-day deadline that catches people, and the AMT trap to model first.
Why anyone exercises early
Stock options let you buy shares at a fixed strike price. The longer you wait, the more the company is usually worth — so the spread (value minus strike) grows, and so does the tax when you finally exercise. Exercising early aims to:
- Pay tax on a small spread — ideally near zero, right after a grant or early in the company's life.
- Start the clocks. Long-term capital gains (1 year) and, for qualifying C-corp stock, QSBS (a potential federal gain exclusion after 5 years) both begin when you own real shares — not when you hold options.
- Convert ordinary income into capital gain on the appreciation that happens after exercise.
The 83(b) election: powerful, and easy to blow
- What it does. If you early-exercise unvested shares, an 83(b) election tells the IRS to tax you now — on today's tiny spread — instead of taxing each chunk as it vests at (likely higher) future values.
- The 30-day rule is hard. You must file within 30 days of exercise. There is essentially no fixing a missed deadline — it's the single most common, most expensive equity mistake.
- It's irrevocable, and it's a bet. If the company soars, you win big. If the shares end up worthless, you don't get back the tax (or the strike) you paid. You're pre-paying on conviction.
The ISO + AMT trap
Incentive stock options (ISOs) get favorable treatment — but hide a cash trap:
- Exercise-and-hold creates no regular income, which feels free. But the spread is an AMT preference item — it can generate a real alternative-minimum-tax bill in the exercise year, on paper gains, with no shares sold to pay it.
- People get hurt exercising deep-in-the-money ISOs before an IPO, owing AMT on a high paper spread — then watching the price fall before they can sell. The tax was real; the value wasn't.
- The AMT you pay often becomes a credit usable in later years, but the cash-flow hit and timing risk are the immediate danger.
- NSOs are simpler and worse on rate: the spread is ordinary income at exercise, with withholding.
This is exactly the "exercise before a liquidity event?" question that option-holding employees face inside a tender or pre-IPO window — and why it should be modeled, not guessed.
How to decide
- Model AMT before exercising ISOs. Estimate the spread × your AMT exposure; know the cash bill before you commit.
- Only risk cash you can lose. Strike + tax on illiquid shares is money you might not get back. Size it like a bet, not a sure thing.
- If early-exercising unvested shares, calendar the 83(b) immediately — 30 days, certified mail, proof retained.
- Map the clocks — when do you cross 1 year (long-term) and, if applicable, 5 years (QSBS) — against likely liquidity windows.
- Coordinate with everything else — a tender or IPO in the same year stacks income; sequencing changes the bill.
Rough out the after-tax picture with the calculator, then get AMT and 83(b) timing modeled properly — these are the decisions where a specialist pays for themselves many times over.
Weighing an early exercise? Model the AMT first.
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