Startup equity comes in several forms — common stock, stock options (ISOs and NSOs), restricted stock awards (RSAs), restricted stock units (RSUs), and LLC membership units — each with different tax treatments, rights, and use cases.
Not all equity is created equal.
Stock options aren’t the same as actual shares. RSUs work differently than restricted stock. LLC membership units follow completely different rules than corporate stock. And the tax implications? They vary wildly depending on which type you hold.
Most founders learn this the hard way. They promise “equity” without understanding what kind, then face awkward conversations when it’s time to formalize agreements.
This guide breaks down every major type of startup equity. What each one is, who typically receives it, the tax treatment, and when you’d actually use it.
The Master Comparison Table
| Type | What You Get | Taxed When | Best For | Entity Type |
|---|---|---|---|---|
| ISOs | Right to buy shares at set price | At sale (if qualified) | Employees | C-Corp |
| NSOs | Right to buy shares at set price | At exercise | Anyone | C-Corp, S-Corp |
| RSAs | Actual shares (with restrictions) | At vesting (or grant with 83(b)) | Founders, early team | C-Corp |
| RSUs | Promise of future shares | At vesting | Later-stage employees | C-Corp |
| LLC Membership Units | Ownership in LLC | Pass-through (annually) | LLC members | LLC |
| Profits Interests | Share of future profits only | At sale (if structured right) | Service providers to LLCs | LLC |
| Common Stock | Basic ownership shares | At sale | Founders, employees | C-Corp |
| Preferred Stock | Shares with special rights | At sale | Investors | C-Corp |
Stock Options
Stock options give you the right to buy shares at a predetermined price. You don’t own anything until you exercise (purchase) them.
This is the most common form of equity compensation for startup employees. But there are two very different flavors.
Incentive Stock Options (ISOs)
ISOs get preferential tax treatment but come with restrictions.
How they work: You receive the option to buy shares at today’s fair market value (the “strike price”). If the company grows and shares become worth more, you can buy at the old lower price and pocket the difference.
Tax treatment: No tax when you receive the options. No ordinary income tax when you exercise (with a big caveat below). You pay capital gains tax when you eventually sell the shares.
The AMT trap: The Alternative Minimum Tax is a parallel tax system. Every year, you calculate your taxes two ways: the regular way, and the AMT way (which disallows certain deductions and adds back certain “preference items”). You pay whichever is higher.
Here’s the problem with ISOs: when you exercise, the spread between your strike price and the current value gets added to your income for AMT purposes, even though it’s not taxed under regular rules.
Example: You exercise 50,000 ISOs at a $1 strike price when the company values shares at $20. Under regular tax, you owe nothing. But for AMT, you add $950,000 to your income. You then calculate AMT (roughly 26-28% on income above the exemption, which is about $88,000 for single filers in 2025). If your AMT bill is higher than your regular tax bill, you pay the AMT amount.
The exemption phases out as income rises, so large ISO exercises almost always trigger AMT. And here’s the real trap: you owe this tax even though you haven’t sold anything. You have shares, not cash. If the stock crashes before you can sell, you still owe the tax on the value at exercise.
This burned countless startup employees during the dot-com bust and again in 2022. They exercised during a boom, owed six-figure AMT bills, then watched the stock crash. Some owed more in taxes than their shares ended up being worth.
The $100K limit: There’s a separate restriction on ISOs: only $100,000 worth of stock (measured at grant-date value) can become exercisable in any calendar year. If you’re granted options on stock worth $2 per share with a 4-year vesting schedule, that’s $50K vesting per year - fine. But if the grant is large enough that more than $100K vests in a year, the excess automatically converts to NSOs and loses the favorable ISO tax treatment.
| ISO Pros | ISO Cons |
|---|---|
| Favorable capital gains treatment | AMT can create surprise tax bills |
| No tax at grant or exercise (regular tax) | Must be employed to exercise |
| Potential for qualified small business stock exclusion | $100K annual vesting limit (excess becomes NSOs) |
| Only available to employees |
Who gets them: Employees only. Not contractors, advisors, or consultants.
Holding requirements: To get the favorable tax treatment, you must hold shares for at least 2 years from grant date AND 1 year from exercise date.
When to Exercise ISOs: The Timing Decision
The “favorable tax treatment” of ISOs is largely theoretical for most startup employees. Because AMT almost always kicks in for any meaningful exercise, you’re left with three practical strategies:
Strategy 1: Exercise early, while the spread is small
If you exercise when shares are worth close to your strike price, there’s little spread to trigger AMT. Many employees exercise as they vest each year rather than waiting.
Pros: Minimal or no AMT. Starts your capital gains clock earlier (you need to hold 1 year from exercise for long-term capital gains rates).
Cons: Requires cash upfront. If the startup fails, you’ve paid real money for worthless shares.
Strategy 2: Same-day sale (disqualifying disposition)
Exercise and sell on the same day. You lose the ISO tax benefit (the spread becomes ordinary income), but you have cash to pay the tax. No AMT complications.
Pros: Predictable taxes. No risk of owing tax on paper gains. Cash in hand.
Cons: Higher tax rate (ordinary income vs. capital gains). No upside if the stock continues to rise.
Strategy 3: Wait for a liquidity event
Don’t exercise until you can actually sell shares (IPO, acquisition, or secondary sale). This is what most employees do by default, often because they don’t understand the alternatives.
Pros: No upfront cash required. No risk of paying for worthless shares.
Cons: If the spread is large, you either trigger massive AMT (Strategy 1 at the worst possible time) or do a same-day sale anyway (Strategy 2). You’ve waited years only to get the same or worse outcome.
The uncomfortable truth: Many tax advisors quietly suggest that NSOs are actually simpler than ISOs. The tax treatment is worse on paper, but it’s predictable. You’re not blindsided by AMT, and you don’t have to make complicated timing decisions.
Early exercise programs
Some startups offer “early exercise” where you can buy unvested shares (which then vest over time). Combined with an 83(b) election, this lets you start the tax clock when shares are worth almost nothing. If you’re at an early-stage startup offering this, it’s often worth considering.
The Complete ISO Guide for Startup Employees
Non-Qualified Stock Options (NSOs)
NSOs are more flexible but less tax-advantaged.
How they work: Same mechanics as ISOs. You get the right to buy shares at a set price.
Tax treatment: When you exercise, the spread between strike price and current fair market value is taxed as ordinary income. Then when you sell, any additional gain is taxed as capital gains.
| NSO Pros | NSO Cons |
|---|---|
| Can be given to anyone (contractors, advisors) | Ordinary income tax at exercise |
| No $100K annual limit | Higher tax burden than ISOs |
| No AMT complications | Less favorable overall tax treatment |
| More flexibility in structuring |
Who gets them: Anyone. Employees, contractors, advisors, board members.
The practical difference: An employee exercises 10,000 ISOs with a $1 strike price when shares are worth $10. With ISOs, no regular income tax is owed (though AMT may apply). With NSOs, they owe ordinary income tax on $90,000 of “income” immediately.
Restricted Stock
Restricted stock means you receive actual shares, but they come with restrictions (usually vesting).
Restricted Stock Awards (RSAs)
RSAs are actual shares granted upfront, subject to vesting.
How they work: You receive real shares on day one. But if you leave before vesting, the company can buy them back (usually at the price you paid, which is often near zero).
Tax treatment: By default, you’re taxed on the value of shares as they vest. If shares are worth $0.01 at grant but $10 when they vest, you owe taxes on the $10 value.
The 83(b) election: This is critical. If you file an 83(b) election within 30 days of receiving shares, you pay taxes on their current value instead of their future vested value. For early founders getting shares worth fractions of a penny, this means paying essentially nothing in taxes now rather than potentially huge amounts later.
| RSA Pros | RSA Cons |
|---|---|
| You own actual shares immediately | Requires payment (even if nominal) |
| 83(b) election can minimize taxes | Must file 83(b) within 30 days |
| Voting rights and dividends from day one | Risk if you leave early and paid real money |
| Simple structure | Not practical at higher valuations |
Who gets them: Founders and very early employees, typically when share values are still very low.
When RSAs stop making sense: Once your company has real value, RSAs become impractical. Nobody wants to pay $50,000 for shares that might vest over four years. That’s when companies switch to options or RSUs.
Restricted Stock Units (RSUs)
RSUs are a promise to give you shares in the future.
How they work: You don’t receive shares upfront. Instead, the company promises to give you shares when they vest. No purchase required.
Tax treatment: When RSUs vest, you receive shares and immediately owe ordinary income tax on their full value. There’s no 83(b) election because you don’t own anything until vesting.
| RSU Pros | RSU Cons |
|---|---|
| No upfront cost | Taxed as ordinary income at vesting |
| No risk of losing money paid for shares | No 83(b) election available |
| Works at any valuation | No ownership rights until vesting |
| Common and well-understood | Less favorable than ISOs for employees |
Who gets them: Employees at later-stage startups and public companies. RSUs became popular because they work regardless of share price and don’t require employees to come up with cash.
LLC Equity
If your company is an LLC (not a C-Corp), equity works differently. There are no “shares” in the traditional sense.
LLC Membership Units
Membership units represent ownership in an LLC.
How they work: You own a percentage of the LLC. This is spelled out in the Operating Agreement. Unlike corporate stock, LLC ownership is highly customizable.
Tax treatment: LLCs are typically “pass-through” entities. The company’s profits and losses flow through to members’ personal tax returns, whether or not any cash is actually distributed. You might owe taxes on “income” you never received.
| Membership Unit Pros | Membership Unit Cons |
|---|---|
| Flexible structuring | Pass-through taxation can mean taxes without cash |
| Single level of taxation | More complex than corporate stock |
| Can customize voting, profit sharing, etc. | Investors often require conversion to C-Corp |
| Good for lifestyle businesses | Harder to grant equity to employees |
Who gets them: LLC founders and members.
The conversion question: If you plan to raise institutional VC money, you’ll almost certainly need to convert to a C-Corp. VCs strongly prefer the standardized structure of corporate stock. For more on this topic, see why LLCs work better for dynamic equity.
Profits Interests
Profits interests are a way to grant equity-like compensation in an LLC without giving away ownership of existing value.
How they work: The recipient gets a share of future profits and appreciation, but no claim on the current value of the company. If the LLC is worth $1M today and you get a 10% profits interest, you’d get 10% of any value above $1M.
Tax treatment: When structured properly, profits interests aren’t taxed at grant. They’re taxed when you eventually receive distributions or sell your interest.
| Profits Interest Pros | Profits Interest Cons |
|---|---|
| No tax at grant (if structured right) | Complex to set up correctly |
| Recipient only shares in future growth | Still subject to pass-through K-1 taxation |
| Good for service providers | Less understood than stock options |
| Preserves existing member value | Requires careful legal work |
Who gets them: Employees, advisors, and service providers to LLCs. It’s the LLC equivalent of stock options.
Why this matters for dynamic equity: If you’re tracking contributions in an LLC, profits interests can be a useful tool. New contributors can earn a stake in future value without claiming a share of what’s already been built.
Why LLCs Work Better for Dynamic Equity
Share Classes
Not all shares have the same rights. Companies create different classes to give different stakeholders different treatment.
Common Stock
Common stock is the basic unit of ownership.
What you get: Ownership, voting rights (usually one vote per share), and the right to any remaining value if the company is sold or liquidated.
The catch: Common stockholders are last in line. In a sale or liquidation, preferred stockholders, debt holders, and others get paid first. Whatever’s left goes to common shareholders.
Who gets it: Founders, employees, advisors. Anyone receiving equity as compensation typically gets common stock.
Preferred Stock
Preferred stock comes with special rights that common stock doesn’t have.
Common preferences include:
- Liquidation preference: Get your money back before common shareholders get anything
- Anti-dilution protection: Adjustment if future rounds are at lower valuations
- Participation rights: Right to participate in future funding rounds
- Board seats: Governance rights
- Dividends: Sometimes a guaranteed dividend rate
Who gets it: Investors. When VCs invest, they almost always receive preferred stock.
Why it matters to founders: In a mediocre exit, preferred stockholders might get paid while common stockholders get nothing. If investors have a 1x liquidation preference on a $10M investment and the company sells for $10M, investors get everything and founders get zero. Understanding what investors look for in cap tables helps you negotiate better terms.
Class A vs Class B (and Beyond)
Companies can create multiple classes of common stock with different voting rights.
The classic structure:
- Class A: One vote per share (held by regular shareholders)
- Class B: Ten votes per share (held by founders)
This lets founders maintain control even as they sell shares or get diluted by investors. Mark Zuckerberg controls Facebook despite owning around 13% of shares because his Class B stock carries 10x voting power.
| Multi-Class Pros | Multi-Class Cons |
|---|---|
| Founders keep control | Investors may push back |
| Can raise money without losing power | Complicates cap table |
| Protects long-term vision | Some see it as poor governance |
Tax Comparison at a Glance
| Equity Type | Taxed at Grant? | Taxed at Vest/Exercise? | Taxed at Sale? |
|---|---|---|---|
| ISOs | No | No (but AMT may apply) | Yes, capital gains |
| NSOs | No | Yes, ordinary income on spread | Yes, capital gains on additional gain |
| RSAs (no 83(b)) | No | Yes, ordinary income on value | Yes, capital gains on additional gain |
| RSAs (with 83(b)) | Yes, on grant value | No | Yes, capital gains |
| RSUs | No | Yes, ordinary income on value | Yes, capital gains on additional gain |
| LLC Units | No | Pass-through annually | Yes, capital gains |
| Profits Interests | No (if structured right) | Pass-through annually | Yes, capital gains |
This is not tax advice. Equity taxation is complex and depends on your specific situation. Work with a tax professional, especially if you’re dealing with significant amounts.
Which Type Should You Use?
If You’re a C-Corp Founder
For yourself: Restricted stock with an 83(b) election. You want actual shares taxed at their current low value.
For early employees: ISOs up to the $100K limit, NSOs beyond that. ISOs are more tax-favorable for employees.
For advisors: NSOs. Advisors can’t receive ISOs since they’re not employees.
If You’re an LLC
For founding members: Membership units, clearly defined in your Operating Agreement.
For service providers: Profits interests. They share in future growth without claiming existing value.
Consider: Whether you’ll eventually convert to a C-Corp. If VC funding is in your future, you’ll need to restructure.
If You’re Raising Money
Expect investors to want: Preferred stock with liquidation preferences and anti-dilution protection.
Consider: Whether multiple share classes make sense to protect founder control.
Common Mistakes
Promising “equity” without specifying type. A handshake agreement to give someone “10% equity” means nothing until you define what kind.
Missing the 83(b) deadline. You have 30 days. Set a calendar reminder. File early. There are no extensions.
Not understanding liquidation preferences. Founders often don’t realize that investors get paid first. A $50M exit might mean $50M for investors and $0 for founders if the numbers don’t work out.
Granting ISOs to non-employees. ISOs are only for employees. Contractors and advisors must receive NSOs.
Ignoring AMT with ISOs. The favorable tax treatment of ISOs disappears if AMT kicks in. Model out the tax implications before exercising.
Using corporate structures for an LLC (or vice versa). Stock options don’t exist in LLCs. Membership units don’t exist in corporations. Match your equity grants to your entity type.
Frequently Asked Questions
What’s the difference between stock options and actual stock?
Stock options give you the right to purchase shares at a set price. You don’t own anything until you exercise (buy) them. Actual stock (like restricted stock) means you own real shares from day one, though they may be subject to vesting restrictions.
Are ISOs better than NSOs?
For employees, usually yes. ISOs have more favorable tax treatment because you don’t owe ordinary income tax at exercise (though AMT may apply). NSOs trigger ordinary income tax immediately upon exercise. However, NSOs are more flexible and can be granted to anyone.
What is an 83(b) election and when should I file one?
An 83(b) election lets you pay taxes on restricted stock at its current value rather than its higher future value when it vests. You should file one when receiving restricted stock that’s currently worth very little. You must file within 30 days of receiving the shares.
How does LLC equity differ from corporate equity?
LLCs don’t have “stock” - they have membership units. The key difference is taxation: LLCs are typically pass-through entities, meaning profits and losses flow to members’ personal tax returns. This can result in owing taxes on income you haven’t actually received as cash.
Figuring out equity structure at the beginning saves enormous headaches later. Use our equity calculator to model different scenarios, then work with a lawyer to formalize the right structure for your situation.
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