Stock Options Explained
Stock options give you the right to buy shares of your company at a fixed price. They are not stock. They are the option to purchase stock at a predetermined price — the strike price — regardless of what the stock is actually worth later. If the company grows, the spread between your strike price and the market price is your profit. If the company does not grow, your options are worthless.
Most stock options expire worthless. This is the uncomfortable truth that neither your recruiter nor your offer letter will emphasize. Understanding how options actually work — the mechanics, the taxes, the risks, and the psychology — is essential for any engineer evaluating a compensation package that includes them.
The Basics
Strike Price
The strike price (also called the exercise price) is the price you pay per share when you exercise your options. It is set when the options are granted, typically at the fair market value (FMV) of the stock on that date.
Example:
You join a startup. The company's FMV is $2.00/share.
You are granted 10,000 options at a $2.00 strike price.
Three years later, the company is valued at $20.00/share.
You exercise: pay $2.00/share x 10,000 = $20,000
You receive shares worth $20.00/share x 10,000 = $200,000
Your paper profit: $180,000
But if the company is still worth $2.00 (or less), your options
have zero value. You would be paying $2.00 for something worth $2.00.
Vesting Schedule
Options vest over time, meaning you earn the right to exercise them gradually. The most common schedule is four-year vesting with a one-year cliff.
Standard 4-year vesting with 1-year cliff:
Month 0-11: 0% vested (nothing — this is the cliff)
Month 12: 25% vests at once (the cliff release)
Month 13-48: ~2.08% vests each month (1/48 per month)
On a 10,000 option grant:
After 1 year: 2,500 options exercisable
After 2 years: 5,000 options exercisable
After 3 years: 7,500 options exercisable
After 4 years: 10,000 options exercisable (fully vested)
The cliff exists to protect the company: if you leave before your first anniversary, you get nothing. After the cliff, vesting is typically monthly, though some companies vest quarterly.
Exercise Window
Once your options vest, you can exercise them — but not forever. While you are employed, vested options are typically exercisable at any time. But when you leave the company, the clock starts ticking.
Post-termination exercise windows:
Standard: 90 days after your last day
Generous: 1-2 years (some companies offer this)
Very rare: 5-10 years (a few employee-friendly companies)
If you do not exercise within the window, your vested options
are forfeited. Gone. Even if the company later goes public
and the shares would have been worth millions.
The 90-day window creates enormous pressure. If you leave a startup with 50,000 vested options at a 10.00, exercising costs $50,000 out of pocket — for shares in a private company you can probably not sell. That is the golden handcuffs problem.
ISOs vs NSOs
There are two types of stock options with different tax treatments:
Incentive Stock Options (ISOs)
ISOs receive favorable tax treatment but come with restrictions.
ISOs:
- Available only to employees (not contractors or advisors)
- No tax at exercise (for regular income tax purposes)
- Gains taxed as long-term capital gains if you hold 2 years
from grant date AND 1 year from exercise date
- Subject to Alternative Minimum Tax (AMT) — the spread at
exercise is an AMT preference item
- $100,000 annual vesting limit (based on FMV at grant date)
- Must be exercised within 90 days of leaving (or they convert to NSOs)
Non-Qualified Stock Options (NSOs)
NSOs are simpler but taxed more heavily.
NSOs:
- Available to anyone (employees, contractors, advisors)
- The spread at exercise is taxed as ordinary income immediately
- Additional gains after exercise are taxed as capital gains
- No AMT considerations
- No $100,000 vesting limit
- Exercise window can be extended beyond 90 days
Tax comparison on 10,000 options, $2 strike, exercised at $20 FMV:
Spread: ($20 - $2) x 10,000 = $180,000
ISO: No regular income tax at exercise, but $180,000 is an AMT
preference item. If you sell after holding period: $180,000
taxed at 15-20% LTCG rate = $27,000-$36,000 tax
NSO: $180,000 taxed as ordinary income at exercise.
At 32% bracket: ~$57,600 tax owed immediately.
Even though you may not be able to sell the shares yet.
Which Is Better
ISOs are generally better due to the capital gains treatment, but the AMT complication can be significant. At large exercise spreads, the AMT bill can be substantial and is due even though you have not sold any shares. You could owe $50,000+ in taxes on paper gains you cannot realize.
Early Exercise & 83(b) Election
Some companies allow you to exercise options before they vest — this is early exercise. It sounds counterintuitive, but it can be an extremely powerful tax strategy.
Early exercise scenario:
You join a startup. 10,000 ISOs at $0.10 strike price (early stage).
You immediately exercise all 10,000 for $1,000 total.
The shares are unvested — the company has a repurchase right
on unvested shares if you leave.
Without 83(b) election:
You are taxed on the spread as each batch of shares vests.
If the stock is worth $5.00 when the first batch vests:
($5.00 - $0.10) x 2,500 shares = $12,250 taxable event
With 83(b) election:
You file an 83(b) election with the IRS within 30 days of exercise.
You declare the spread at the time of exercise as income.
Spread at exercise: ($0.10 - $0.10) x 10,000 = $0
Tax owed: $0
All future appreciation is taxed as capital gains, not income.
If the company exits at $50/share:
($50 - $0.10) x 10,000 = $499,000 taxed at LTCG rates (15-20%)
vs ordinary income rates (32-37%) without the 83(b).
Tax savings: potentially $80,000-$100,000+
The 83(b) election must be filed within 30 days of exercise. Miss the deadline and you cannot file it. There are no extensions and no exceptions. Mark it on your calendar the day you early-exercise.
The Risk of Early Exercise
You are paying real money for shares that might become worthless. If the startup fails (and most do), you lose your exercise cost with no tax benefit beyond a capital loss deduction limited to $3,000/year.
Early exercise risk calculation:
Exercise cost: $1,000 (10,000 shares x $0.10)
If company fails: you lose $1,000
If company exits at $50/share: you gain ~$499,000 at LTCG rates
The math favors early exercise when:
- Strike price is very low (early-stage company)
- Your total exercise cost is money you can afford to lose
- You believe in the company's prospects (even knowing the base rate)
What Happens When You Leave
This is where options get painful. When you leave a company — voluntarily or through a layoff — your unvested options disappear. Your vested options are subject to the exercise window.
Scenario: 3 years into a 4-year vest, you have 7,500 vested options
Strike price: $1.00
Current 409A valuation: $15.00
Exercise cost: 7,500 x $1.00 = $7,500
AMT exposure (ISOs): 7,500 x ($15.00 - $1.00) = $105,000
You have 90 days to decide:
- Exercise: pay $7,500 cash + potential AMT on $105,000
for shares in a private company you cannot sell
- Walk away: lose 7,500 options that might be worth $105,000+
The 2,500 unvested options? Gone. No choice involved.
This is the golden handcuffs. Leaving a successful startup can cost tens or hundreds of thousands of dollars in exercise costs and tax bills. Engineers stay at companies they want to leave because they cannot afford to exercise their options.
Strategies for Leaving
- Exercise before leaving: if you have been early-exercising gradually,
this is not a crisis. All vested shares are already exercised.
- Negotiate an extended window: some companies will extend the
exercise window as part of a departure negotiation. Ask.
- Exercise and hold: if you can afford the exercise cost and tax,
exercise and bet on the upside. Only do this with money you
can genuinely afford to lose.
- Walk away: if the exercise cost plus taxes exceeds what you can
risk, forfeiting the options is a legitimate choice. Sunk cost
fallacy applies here — the vesting time is already spent.
The Golden Handcuffs Problem
Golden handcuffs are not just about options. They are about the psychological trap of staying in a job you want to leave because the financial cost of leaving feels too high.
Signs you are in golden handcuffs:
- You would leave but "my options are worth too much"
- You are unhappy but waiting for the next vesting event
- You are making career decisions based on unvested equity
rather than learning, growth, or fulfillment
- You have been "about to leave after the next vest" for 2+ years
The antidote is honest math. Calculate the actual expected value of your unvested options — which requires discounting for the probability that the company never has a liquidity event. For most startups, that discount is 70-90%.
Unvested options paper value: $500,000
Probability of liquidity event: 20-30%
Expected value: $100,000-$150,000
Opportunity cost of staying: possibly higher
A new job with a $30,000 salary increase over 3 years = $90,000
guaranteed, vs $100,000-$150,000 expected but uncertain.
The Uncomfortable Truth About Options
Most stock options expire worthless. This is not pessimism — it is the base rate.
Startup outcomes (approximate):
- 90% of startups fail entirely (options worth $0)
- 7% have modest exits (options might cover exercise cost)
- 2-3% have significant exits (options worth real money)
- <1% become unicorns (options life-changing)
Options are a bet. They can pay off enormously. But treating them as guaranteed compensation — counting on them for your retirement, your house down payment, or your financial plan — is financially reckless.
Value options at $0 for financial planning purposes until a liquidity event actually occurs. Everything else is paper.
Common Pitfalls
- Counting options as guaranteed income. Until there is a liquidity event, options are worth zero for planning purposes. Do not factor them into your budget, savings plan, or major purchase decisions.
- Missing the 83(b) election deadline. You have exactly 30 days from the date of early exercise. There are no extensions. Mail the form certified with return receipt. Keep a copy forever.
- Not understanding AMT before exercising ISOs. The AMT on a large ISO exercise can be a six-figure tax bill. Consult a tax professional before exercising ISOs worth more than $50,000 in spread.
- Exercising with money you cannot afford to lose. If the company fails, your exercise cost is gone. Only exercise with money you have genuinely written off.
- Staying at a company solely because of unvested options. Calculate the expected value (paper value times probability of liquidity). Compare it to the career opportunity cost of staying. Make a rational decision, not an emotional one.
- Ignoring the exercise window when leaving. The 90-day clock starts on your last day. If you do not make a decision by then, the decision is made for you: you lose the options.
- Assuming your share count is meaningful without knowing total shares outstanding. 100,000 options sounds like a lot. But if there are 100 million shares outstanding, you own 0.1% of the company. Always ask about your ownership percentage, not just the number of shares.
- Not planning for the tax bill at exercise. NSO exercises create an immediate ordinary income tax obligation. ISO exercises can create an AMT obligation. In both cases, you may owe taxes on gains you cannot yet realize in cash. Set aside the tax money before exercising.
Key Takeaways
- Stock options are the right to buy shares at a fixed strike price. They are not stock, and they are not guaranteed compensation.
- ISOs get favorable tax treatment (capital gains vs ordinary income) but trigger AMT at exercise. NSOs are taxed as ordinary income at exercise but have no AMT complication.
- Standard vesting is 4 years with a 1-year cliff. If you leave before the cliff, you get nothing.
- Early exercise plus an 83(b) election can save significant taxes at early-stage companies where the strike price is very low. The filing deadline is 30 days with no exceptions.
- The 90-day post-termination exercise window creates the golden handcuffs problem: leaving can cost real money in exercise costs and taxes.
- Most startup stock options expire worthless (90%+ of startups fail). Value options at $0 for financial planning until a liquidity event occurs.
- Always ask about your ownership percentage, not just your share count. Shares without context are meaningless.
- Consult a tax professional before exercising options with a spread exceeding $50,000. The tax implications of ISOs and AMT are complex enough to justify professional advice.