Complete guide to equity compensation: ISO vs NSO vs RSU, 409A valuations, 83(b) elections, early grants, and Delaware vs California law differences. Interactive tax calculators included.
Best Tax Treatment
Most Flexible
No Purchase Required
Equity compensation is how startups attract and retain talent when cash is tight. But the tax and legal complexity is significant. This guide explains the three main types of equity awards, how they're valued, and how to avoid costly tax mistakes.
Best For: Employees (not contractors, not advisors)
Tax Advantage: If you hold for 2 years from grant + 1 year from exercise, all gains are taxed as long-term capital gains (0-20%) instead of ordinary income (up to 37%)
Best For: Contractors, advisors, or when ISO limits are exceeded
Tax Treatment: Spread at exercise is taxed as ordinary income (W-2 wages). Future gains taxed as capital gains.
Best For: Later-stage companies with high 409A valuations
Tax Treatment: Entire value taxed as ordinary income at vest (no purchase required)
When I help founders design equity compensation plans, I use this decision tree:
You cannot legally grant stock options without a 409A valuation that establishes the "fair market value" of your common stock. Granting options below 409A FMV triggers immediate taxes for the recipient and penalties for the company. I explain 409A valuations in detail in the dedicated tab.
I've seen these mistakes cost founders and employees hundreds of thousands in unnecessary taxes:
This guide will help you avoid all of these mistakes.
| Feature | ISO | NSO | RSU |
|---|---|---|---|
| Who Can Receive | W-2 employees only | Anyone (employees, contractors, advisors) | Anyone (typically employees) |
| Purchase Required? | Yes (exercise price = 409A FMV at grant) | Yes (exercise price = 409A FMV at grant) | No (shares delivered automatically at vest) |
| Vesting Schedule | Typically 4-year vest, 1-year cliff | Typically 4-year vest, 1-year cliff | Typically 4-year vest, 1-year cliff |
| Tax on Grant | $0 (no tax at grant) | $0 (no tax at grant) | $0 (no tax at grant) |
| Tax on Vest | $0 (no tax at vest, only at exercise) | $0 (no tax at vest, only at exercise) | Ordinary income tax on full FMV |
| Tax on Exercise | $0 regular tax, but AMT on spread (FMV - strike price) | Ordinary income tax on spread (FMV - strike price) | N/A (no exercise) |
| Tax on Sale | Long-term capital gains (0-20%) if hold 2 years from grant + 1 year from exercise | Capital gains on appreciation after exercise | Capital gains on appreciation after vest |
| Best Tax Outcome | Entire gain taxed at 0-20% (long-term capital gains) | Spread taxed at 37%+ ordinary; gains at 15-20% capital gains | All value taxed at 37%+ ordinary until you sell |
| AMT Risk | ⚠️ Yes (can be significant if 409A is high at exercise) | No AMT | No AMT |
| Vesting Limit | $100K FMV/year (excess becomes NSO) | No limit | No limit |
| Exercise Window After Termination | 90 days (or lose ISO treatment and become NSO) | 90 days standard (but negotiable) | N/A (unvested RSUs forfeit; vested RSUs are yours) |
| Early Exercise Allowed? | Yes (if plan allows), requires 83(b) election | Yes (if plan allows), requires 83(b) election | No (RSUs cannot be early exercised) |
| Typical Use Case | Early employees at startups (strike price $0.10-$5.00) | Contractors, advisors, or when ISO limits exceeded | Later-stage startups (409A > $10) or public companies |
Let's compare tax outcomes for an employee receiving 100,000 options with a $1.00 strike price. Company exits 5 years later at $50/share.
| Scenario | ISO (Qualifying Disposition) | NSO | RSU (100K shares worth $1 at grant) |
|---|---|---|---|
| Cost to Exercise | $100,000 (100K options × $1 strike) | $100,000 (100K options × $1 strike) | $0 (no exercise required) |
| Tax at Exercise (assuming $10 FMV) | $0 regular tax AMT: ($10 - $1) × 100K × 28% = $252K AMT (may get credit later) |
Ordinary income tax: ($10 - $1) × 100K = $900K income Tax: ~$333K (37% federal) |
N/A |
| Tax at Vest (assuming $10 FMV) | N/A | N/A | Ordinary income tax: $10 × 100K = $1M income Tax: ~$370K (37% federal) |
| Tax at Sale ($50/share) | Long-term capital gains: ($50 - $1) × 100K = $4.9M gain Tax: ~$980K (20% federal) |
Capital gains: ($50 - $10) × 100K = $4M gain Tax: ~$800K (20% federal) |
Capital gains: ($50 - $10) × 100K = $4M gain Tax: ~$800K (20% federal) |
| TOTAL TAX | ~$980K (AMT credit may reduce this) |
~$1,133K ($333K + $800K) |
~$1,170K ($370K + $800K) |
| NET PROCEEDS | ~$3,920K | ~$3,767K | ~$3,830K |
| Cash Required Upfront | $100K (exercise) + up to $252K (AMT) | $100K (exercise) + $333K (tax) | $0 (but $370K withheld from shares at vest) |
ISOs save ~$150K-200K in taxes vs NSOs or RSUs in this scenario, but require significant cash upfront ($100K exercise + potential $252K AMT bill). NSOs and RSUs have similar total tax but different timing.
The $252K AMT in the ISO scenario above is not a permanent tax—it's a timing difference. You get an AMT credit you can use in future years when your regular tax exceeds your AMT. However:
I help clients model AMT risk and decide whether to exercise ISOs early (when 409A is low and AMT is minimal).
A 409A valuation is an independent appraisal of your company's common stock fair market value (FMV). It's required by IRS Section 409A to avoid immediate taxation and penalties when granting stock options.
If you grant options with a strike price below the 409A FMV, the IRS treats the discount as immediate taxable compensation to the recipient, plus:
A startup granted its first 10 employees options at $0.10/share in 2018 without a 409A. In 2019, they got a 409A showing FMV was actually $5.00/share in 2018. IRS determined each employee with 100K options received $490K of taxable compensation ($5.00 - $0.10 × 100K), triggering:
Several employees quit and sued the company. Never grant options without a 409A.
The IRS provides "safe harbor" — if you follow these methods, the IRS presumes your valuation is correct unless they can prove it's unreasonable:
Hire a qualified valuation firm (409A specialist). They use one or more methods:
Cost: $2,000-5,000 for early-stage; $5,000-15,000 for later-stage
Timeline: 1-3 weeks
This is the method you'll encounter most if you raise VC money:
Preferred stock has valuable rights that common stock lacks:
The 409A model values these rights and discounts common stock accordingly. The discount increases as more preferred rounds stack on top (Series B preferred is senior to Series A, which is senior to common).
You form a Delaware C-Corp and issue founder stock (83(b) election filed). No 409A needed yet — founder stock purchases are at par value ($0.0001/share).
CRITICAL: Before granting first employee stock options, you MUST get a 409A valuation. Budget $2,000-3,500.
For pre-revenue companies, 409A common stock FMV is typically $0.05-0.25/share.
You raise $2M on a SAFE or convertible note. Technically no 409A update required yet (no preferred stock issued), but advisable if valuation changed significantly.
You raise $10M Series A at $10/share preferred (post-money $50M). You MUST get a new 409A immediately after closing.
New 409A uses "backsolve" method. Common stock FMV jumps from $0.10 to $2.50/share (25% of preferred).
Update 409A annually or after any material event (new funding, acquisition offer, 3x revenue growth, etc.).
Since higher 409A = higher strike price = worse for option recipients, founders often ask how to keep 409A valuations low. Legal strategies:
The IRS heavily scrutinizes 409A valuations. If your valuation is unreasonably low and the IRS challenges it, you lose safe harbor protection. Strategies above are legal, but outright manipulation (lying about revenue, hiding term sheets, etc.) is illegal and will backfire.
I don't receive referral fees from these companies — these are just the firms my clients have had good experiences with:
For simple pre-revenue companies, Carta is usually the best value. For complex situations (multiple classes of preferred, warrants, etc.), Aranca or Valor provide more sophisticated analysis.
An 83(b) election is a letter you send to the IRS within 30 days of receiving restricted stock or early exercising stock options. It can save founders and early employees millions in taxes, but if you miss the 30-day deadline, the opportunity is lost forever.
Normally, when you receive restricted stock or exercise options that vest over time, you're taxed as the shares vest. With an 83(b) election, you elect to be taxed on the full value immediately (at grant/exercise), even though the shares are restricted.
Imagine you're a founder. You receive 1,000,000 shares of restricted stock (4-year vest) at $0.001/share when the company is worth nothing. Without 83(b):
With 83(b) filed at grant:
| Scenario | 83(b) Required? | Why |
|---|---|---|
| Founder purchasing restricted stock at incorporation | ✅ YES (critical) | Without 83(b), you're taxed as shares vest over 4 years. With company growth, this can mean millions in ordinary income tax. |
| Early employee early exercising unvested ISOs | ✅ YES (critical) | Starts the 1-year capital gains holding period and avoids AMT on future appreciation. |
| Early employee early exercising unvested NSOs | ✅ YES (critical) | Avoid ordinary income tax on spread as shares vest. Start capital gains holding period. |
| Employee exercising vested ISOs | ❌ NO (not applicable) | Shares are already vested, so no restriction = no 83(b) election needed. |
| Employee receiving RSUs | ❌ NO (cannot file) | RSUs are not actual stock — they're a promise to deliver stock at vest. 83(b) only applies to actual restricted stock. |
| Contractor receiving restricted stock for services | ✅ YES | If stock is restricted/vests over time, you'll be taxed as it vests unless you file 83(b). |
The 83(b) election is surprisingly simple — it's a one-page letter you mail to the IRS. But the 30-day deadline is absolute. If you miss it by even one day, you cannot file and lose the tax benefit forever.
You've incorporated, you need to hire your first employee, and they want equity. But you don't have a formal stock option plan yet (and creating one costs $5,000-10,000 in legal fees). What do you do?
Most startup lawyers will tell you: "You need to adopt a formal equity incentive plan (2023 Stock Plan), have your board approve it, get a 409A valuation, then grant options pursuant to the plan."
But this takes 2-4 weeks and costs $5K-10K (lawyer) + $2K-4K (409A) = $7K-14K. If you're pre-funding, you don't have this cash.
You can grant stock options outside of a formal plan using standalone option agreements. This is completely legal and commonly done by early-stage startups.
Cost: $500-1,500 in legal fees (vs $5K-10K for a full plan)
| Scenario | Recommendation | Why |
|---|---|---|
| Pre-seed, first 1-3 employees | Non-plan options | Save $5K-8K. You can fold these into a formal plan later. |
| Post-seed, hiring 5+ employees | Adopt formal plan | Easier to administer, standardized terms, VC/investor expectation. |
| Post-Series A | Formal plan (required) | VCs require it. Board/compensation committee oversight. ISO $100K limit tracking. |
| Advisor equity | Either works | Advisors typically get small grants (0.1-0.5%), non-plan is fine. |
This is non-negotiable. You cannot grant options without a 409A, whether using a plan or not.
Cost: $1,500-3,000 for early-stage company
Timeline: 1-2 weeks
Agree on:
Your lawyer drafts a standalone option agreement including:
Cost: $500-1,000 (first agreement); $200-400 for subsequent grants (template reuse)
Board of directors (even if it's just you, the founder) must approve the grant via written consent or board meeting minutes.
Board resolution should state:
Employee reviews and signs the stock option agreement. Provide them with:
Add the option grant to your cap table (use Carta, Pulley, or a spreadsheet). File the signed agreement and board resolution with corporate records.
When you raise a seed or Series A round, investors will want you to adopt a formal equity incentive plan. Your non-plan options can be:
Either way, the employee's rights don't change. They keep their original strike price, vesting schedule, and terms.
Some founders ask: "Can I just grant options at $0.0001/share like I did for founder stock, without a 409A?"
NO. Founder stock at incorporation is different — founders are purchasing at par value (legally acceptable). Employees receiving options months later, after you've built product/raised money, cannot use par value. You must use 409A FMV or face severe tax penalties.
Employee: First engineering hire, employee #1
Negotiated equity: 1% of fully diluted cap
Current cap table: 8M shares outstanding (founders only)
Option pool (planned): 15% = 1.4M shares
This employee's grant: 1% × (8M + 1.4M) = 94,000 options
409A FMV: $0.10/share (just completed)
Strike price: $0.10/share
Vesting: 4 years, 1-year cliff, monthly thereafter
Early exercise: Allowed (employee can buy unvested shares and file 83(b))
Exercise window: 90 days post-termination (negotiate for 7-10 years if possible)
Type: ISO (they're W-2 employee)
For advisors (not employees), you have additional alternatives to options:
I typically recommend NSO grants for advisors (4-year vest, 0.1-0.5% equity) or restricted stock with 83(b) if the 409A is very low ($0.01-0.10).
Use this calculator to compare tax outcomes for different equity compensation types:
Most venture-backed startups are Delaware corporations, but many have employees in California. This creates tension between Delaware corporate law and California employment law.
| Issue | Delaware Law | California Law | What Applies |
|---|---|---|---|
| Exercise Window After Termination | Company decides (typically 90 days) | No specific law, but CA courts may find very short windows (30 days) unconscionable | Delaware law governs (you're a DE corp), but CA employees may challenge in court |
| Acceleration on Termination Without Cause | Not required | Not required | Negotiable (some employees negotiate partial acceleration) |
| Repurchase Rights (Company Can Buy Back Vested Shares) | Allowed (common in early grants) | Allowed, but must be at FMV | Both allow it; DE corp docs govern terms |
| Non-Compete Restrictions | Enforceable (if reasonable) | Void (CA Bus. & Prof. Code § 16600) | CA law wins for CA employees — non-competes unenforceable even in DE corp option agreements |
| Forfeiture-for-Competition Clauses | Allowed | Void (cannot forfeit vested equity for competing) | CA law wins for CA employees — cannot force vested equity forfeiture |
| Disclosure Requirements | Minimal (provide plan document) | CA Labor Code § 2803: Must disclose all material terms, tax consequences | CA law applies to CA employees — must provide detailed disclosures |
| Right to Transfer/Assign Options | Company decides (typically prohibited) | Same, but CA may require allowing transfer to family trusts | DE corp plan governs, but allow trust transfers to avoid CA challenge |
| Clawback Provisions (Forfeit Equity for Misconduct) | Allowed (increasingly common post-Dodd-Frank) | Allowed for unvested equity; vested equity clawback must be reasonable | Both allow it for misconduct (fraud, violation of fiduciary duty) |
This is the biggest landmine for Delaware corporations with California employees:
Many Delaware stock option plans include provisions like:
These clauses are VOID and unenforceable for California employees under California Business & Professions Code § 16600, which states:
"Except as provided in this chapter, every contract by which anyone is restrained from engaging in a lawful profession, trade, or business of any kind is to that extent void."
California courts interpret this very broadly. Even Delaware choice-of-law provisions don't save you — CA courts will apply CA law to CA employees' equity.
Beyond Delaware and California, a few other states have unique equity compensation rules:
If you have employees in these states, review your stock option plan for non-compete/forfeiture clauses that may be unenforceable.
While California employment law creates challenges, Delaware corporate law offers key advantages for equity compensation:
Some lawyers draft option agreements with provisions like: "This agreement is governed by Delaware law, regardless of employee's location."
This doesn't work for California employees. CA courts will apply CA employment law to CA employees, period. Attempting to override this with choice-of-law clauses just creates false confidence and exposes you to liability when the clause is later invalidated.
Designing and implementing a stock option plan is complex. Tax mistakes can cost employees hundreds of thousands of dollars. Legal mistakes can expose your company to liability. Let me help you get it right.
Fill out this form and I'll email you within 24 hours with recommendations and a quote:
Sergei Tokmakov, Esq.
I'm a business attorney specializing in startup equity compensation, Delaware corporations, and 409A compliance. I've helped hundreds of founders design equity plans, avoid tax mistakes, and navigate the complexity of ISO/NSO/RSU taxation.
I work with early-stage founders who need pragmatic, cost-effective solutions (non-plan options, 83(b) filings) and later-stage companies that need sophisticated equity plans with California compliance.
Contact: Use the form above or email directly at owner@terms.law