RSUs and stock options are the two most common forms of equity compensation, but they work in fundamentally different ways. RSUs are granted shares that vest over time and always have value as long as the company stock is worth anything. Stock options give you the right to buy shares at a fixed price (the strike price) --- they can be extremely valuable if the stock price rises, but worthless if it falls below your strike.
This guide covers every meaningful difference between RSUs and stock options, with worked examples showing how each performs in different market conditions.
The Fundamental Difference
RSUs (Restricted Stock Units): Your company promises to give you a certain number of shares when they vest. You pay nothing to receive them. On the vesting date, the shares are yours and the full fair market value is taxed as ordinary income.
Stock Options: Your company gives you the right to buy shares at a specific price (the strike/exercise price). You must decide whether to exercise (buy) and when. The value is the difference between the current stock price and your strike price --- if the stock price is below your strike, the options are "underwater" and have no value.
Side-by-Side Comparison
| Feature | RSUs | Stock Options |
|---|---|---|
| What you receive | Actual shares at vesting | Right to buy shares at strike price |
| Exercise cost | None --- shares are free | Must pay strike price x number of shares |
| Value if stock drops 50% | Still worth 50% of original value | May be worthless (if below strike) |
| Tax timing | At vesting (automatic) | At exercise (you choose when) |
| Tax type at receipt | Ordinary income on full FMV | Depends on option type (ISO vs NSO) |
| Tax control | Little --- vest dates are fixed | Significant --- you choose when to exercise |
| Upside potential | Linear with stock price | Leveraged --- all upside, no downside below strike |
| Typical company stage | Public companies, late-stage startups | Early-stage startups |
| Complexity | Simple --- shares vest, you pay tax | Complex --- exercise timing, AMT, holding periods |
Value Comparison: Up, Flat, and Down Markets
Let's compare 1,000 RSUs granted at $100/share vs 1,000 stock options with a $100 strike price. Both have the same notional value at grant ($100,000).
Stock Goes Up to $150
| RSUs | Stock Options | |
|---|---|---|
| Value at vest/exercise | 1,000 x $150 = $150,000 | 1,000 x ($150 - $100) = $50,000 |
| Tax (assuming 35% combined rate) | $52,500 | $17,500 (NSO) or $0 regular + AMT (ISO) |
| After-tax value | $97,500 | $32,500 (NSO) |
RSUs are worth 3x more in dollar terms because you get the full value, not just the appreciation.
Stock Stays Flat at $100
| RSUs | Stock Options | |
|---|---|---|
| Value at vest/exercise | 1,000 x $100 = $100,000 | 1,000 x ($100 - $100) = $0 |
| Tax | $35,000 | $0 |
| After-tax value | $65,000 | $0 |
RSUs still deliver $65,000 after tax. Options are worthless.
Stock Drops to $60
| RSUs | Stock Options | |
|---|---|---|
| Value at vest/exercise | 1,000 x $60 = $60,000 | 1,000 x ($60 - $100) = $0 (underwater) |
| Tax | $21,000 | $0 |
| After-tax value | $39,000 | $0 |
RSUs are lower risk, lower reward. They always have value but cannot deliver the outsized returns that options provide in a high-growth scenario. Options are higher risk, higher reward --- they're worthless if the stock doesn't appreciate, but offer leveraged upside when it does.
Tax Treatment Differences
RSU Taxation
RSUs are taxed as ordinary income when they vest. The full FMV of the shares on the vest date appears on your W-2. Your employer withholds taxes at the supplemental rate (22% federal, or 37% for amounts exceeding $1M in a calendar year).
After vesting, any additional appreciation is taxed as a capital gain when you sell --- long-term if held over 1 year post-vest, short-term otherwise.
For a complete guide, see how RSUs are taxed and our RSU tax rate breakdown.
Stock Option Taxation
Tax timing depends on the option type:
- NSOs: Ordinary income at exercise on the spread (FMV minus strike). Capital gains at sale on any additional appreciation.
- ISOs: No regular income tax at exercise (but AMT may apply). If you hold 1 year from exercise + 2 years from grant, the entire gain qualifies for LTCG rates.
For exercise timing strategies, see when to exercise stock options.
Key Tax Distinction
With RSUs, you have no control over tax timing --- taxes hit when shares vest, which is determined by your vesting schedule. With stock options, you choose when to exercise, giving you the ability to spread exercises across tax years, time around income fluctuations, or wait for a liquidity event.
This tax control is one of the most underappreciated advantages of stock options. Our equity compensation calculator can help you model both scenarios.
When Companies Use Each Type
| Company Stage | Typical Equity Type | Why |
|---|---|---|
| Seed / Series A | Stock options (ISOs) | Low FMV means low strike price; employees want leveraged upside |
| Series B-D | Mix of options and RSUs | Growing FMV makes options expensive; RSUs for later hires |
| Late-stage / Pre-IPO | RSUs (mostly) | High FMV makes option strike prices expensive; RSUs are simpler |
| Public company | RSUs (almost exclusively) | No exercise cost, simpler administration, always have value |
If you're evaluating a job offer with stock options, make sure you understand the current 409A valuation (FMV) relative to your strike price. A startup offering options at a $1 strike when the 409A is $1 is giving you leveraged upside. A late-stage company offering options at a $50 strike when the 409A is $55 is giving you only $5/share of built-in value --- far less attractive than RSUs worth $55/share.
Worked Example: Comparing a Job Offer
You have two offers for equivalent roles:
- Company A (Public): $200,000 base + 1,000 RSUs vesting over 4 years. Stock price: $150.
- Company B (Startup): $180,000 base + 10,000 ISOs vesting over 4 years. Strike: $10. Latest 409A: $10.
If Company B's Stock Reaches $50/Share in 4 Years
| Company A (RSUs) | Company B (ISOs) | |
|---|---|---|
| Equity value (pre-tax) | 1,000 x $150 = $150,000 | 10,000 x ($50 - $10) = $400,000 |
| Annual equity value | $37,500/yr | $100,000/yr |
| Total comp (annual) | $237,500 | $280,000 |
Company B wins by $42,500/year --- but only if the stock reaches $50.
If Company B's Stock Stays at $10/Share
| Company A (RSUs) | Company B (ISOs) | |
|---|---|---|
| Equity value (pre-tax) | 1,000 x $150 = $150,000 | 10,000 x ($10 - $10) = $0 |
| Annual equity value | $37,500/yr | $0/yr |
| Total comp (annual) | $237,500 | $180,000 |
Company A wins by $57,500/year. The options are worthless.
This illustrates the risk/reward tradeoff perfectly. RSUs are a guaranteed component of your compensation. Options are a bet on the company's future.
Calculate RSU Withholding
Estimate your RSU tax withholding and net proceeds after vesting.
Try Calculator →Concentration Risk: The Hidden RSU Problem
RSUs automatically deliver shares on a fixed schedule --- which means you passively accumulate employer stock without making any active decision. After 3-4 years of initial vesting plus annual refresh grants, it is common for tech employees to have 30-50% of their net worth in a single stock. This is a significant, often unrecognized risk.
Stock options create a natural checkpoint: you must actively decide to exercise, which forces you to evaluate whether you want more exposure to your employer's stock. Many option holders never exercise at all, effectively choosing cash over concentration.
Practical rules for managing RSU concentration:
- Consider selling at vest. Treat each RSU vest like a cash bonus --- would you use that cash to buy your employer's stock today? If not, sell and diversify.
- Set a maximum threshold. Many financial advisors recommend no more than 10-20% of your investable portfolio in any single stock, including your employer. Review quarterly.
- Automate diversification. Some brokers allow you to set up automatic sell orders on vest dates, removing the emotional decision from the equation.
For how RSU sales affect your tax return, see our guide to how equity compensation affects your tax return.
The 90-Day Post-Departure Exercise Window
When you leave a company with vested stock options, most grant agreements give you 90 days from your last day of employment to exercise. After 90 days, unexercised vested ISOs convert to NSOs (losing their preferential tax treatment), and shortly after, they expire entirely.
The cash crunch scenario: Imagine leaving a startup with 10,000 vested ISOs at a $5 strike price and $25 FMV. Exercising all of them requires $50,000 in cash for the strike price, plus potential AMT on the $200,000 spread --- which could add another $30,000-$55,000 in tax due at filing time. You have 90 days to come up with this money or lose the options.
RSUs have no such deadline. Vested RSUs are already your shares. When you leave, they sit in your brokerage account. There is no exercise decision, no cash outlay, and no ticking clock. Unvested RSUs are typically forfeited, but that is a known quantity --- you never had to risk cash to claim them.
Extended exercise windows: Some companies (notably Coinbase, Pinterest, and Palantir) now offer extended post-termination exercise periods of up to 10 years. This dramatically changes the equation, letting you defer the exercise decision (and the tax bill) until you have more information. Always check your specific grant agreement. For more on exercise timing, see our guide on when to exercise stock options.
Cash Flow Comparison: RSUs vs Stock Options
The table below illustrates the cash required at different grant sizes, assuming a $50 FMV and $5 strike price (options) or $50 FMV (RSUs). AMT estimated at 26% of the spread above the $88,100 exemption for a single filer with $150K salary.
| Grant Size | RSU Cash Outlay | ISO Exercise Cost | Estimated AMT on Spread |
|---|---|---|---|
| 1,000 shares | $0 | $5,000 | ~$2,494 |
| 5,000 shares | $0 | $25,000 | ~$32,994 |
| 10,000 shares | $0 | $50,000 | ~$62,494 |
| 20,000 shares | $0 | $100,000 | ~$124,994 |
RSUs require zero cash. Stock options can demand six figures in exercise costs plus tens of thousands in AMT --- money you need before seeing any return. For employees without significant savings, this cash requirement makes options effectively illiquid.
Startup vs Public Company Equity
The company stage largely determines which equity type you receive, and for good reason:
Startups (Seed through Series A): ISOs dominate. The 409A valuation is low (often $0.10-$2.00/share), so the exercise cost is minimal. At these early stages, the upside potential from LTCG treatment on future appreciation far outweighs the small AMT risk. Some founders and very early employees receive restricted stock with 83(b) elections instead, locking in pennies of ordinary income for shares that may one day be worth hundreds of dollars.
Growth stage (Series B-D): A mix emerges. Early employees still hold ISOs from earlier grants, but newer hires increasingly receive RSUs. The 409A has risen to $10-$50/share, making ISO exercise costs meaningful and AMT exposure significant. Companies find RSUs simpler to administer and more attractive to candidates who do not want to worry about exercise decisions.
Public companies: RSUs almost exclusively. With share prices at $50-$300+, the exercise cost of options would be prohibitive. RSUs vest automatically, can be sold immediately to cover taxes, and always have value. The simplicity and guaranteed value is why every major tech company --- Google, Apple, Amazon, Meta, Microsoft --- uses RSUs as their primary equity vehicle.
For a tool to model these scenarios, see our equity compensation calculator.
Frequently Asked Questions
Can I have both RSUs and stock options?
Yes. Many companies (especially during the transition from startup to public) grant RSUs to new hires while existing employees still hold stock options from earlier grants. Some companies also grant a mix intentionally.
Which is better for early-stage startup employees?
Stock options are typically better at early-stage companies because the strike price is very low. This means you can buy shares cheaply and potentially benefit from long-term capital gains treatment (with ISOs). RSUs at an early-stage company would generate a tax bill at vesting even though you cannot sell the shares.
Do RSUs require any action on my part?
Generally no. RSUs vest automatically on the scheduled dates. Your employer handles withholding by selling some shares (sell-to-cover) or withholding shares (net settlement). You do not need to make an exercise decision. However, you should plan for potential withholding shortfalls.
What happens to stock options if I leave the company?
Most stock option agreements give you 90 days after departure to exercise vested options or they expire. Some companies offer extended exercise windows (up to 10 years). RSUs that haven't vested are typically forfeited --- but vested RSUs are already shares you own.
Can stock options become RSUs?
Not directly. However, during an IPO or acquisition, companies sometimes convert outstanding options to RSUs as part of a restructuring. This is a company decision, not something you can elect individually.
Tax Disclaimer: This content is for educational purposes only. Always consult with a licensed tax professional or certified public accountant before making financial decisions related to equity compensation, tax planning, or investment strategies.