Stock Options, RSUs & Equity Compensation: The US Tax Guide for Founders & Employees

Stock Options, RSUs & Equity Compensation: The US Tax Guide for Founders & Employees

Equity compensation—stock options, restricted stock units (RSUs), and employee stock purchase plans (ESPPs)—can represent a huge portion of your wealth. Yet many founders, executives and employees are blindsided by the tax bill when they exercise, vest or sell. The IRS treats each form of equity differently, and timing matters enormously. This guide walks you through how the US tax system treats equity, what you'll owe, and how to plan strategically.

Why Equity Taxes Are Complicated

Unlike salary, which is straightforward W-2 income, equity compensation triggers multiple tax events:

• Vesting date — when restricted stock or RSUs become yours
• Exercise date — when you buy shares under an option
• Sale date — when you convert your stake to cash

Each event can trigger ordinary income tax, capital gains tax, or both. The type of option you hold, your holding period, and your income level all affect your total bill. A miscalculation can cost tens or hundreds of thousands of dollars.

The Four Main Types of Equity Compensation

Non-Qualified Stock Options (NSOs)

Non-qualified stock options are the most common form of equity at startups and larger companies. When you exercise an NSO:

• You pay the strike price and receive shares
• The difference between strike price and fair market value (FMV) at exercise is ordinary income taxed at your marginal rate
• This is called the "spread," and you owe federal, state, and FICA taxes on it immediately—even if you hold the shares and don't sell
• When you later sell the shares, any gain or loss above the FMV at exercise is taxed as capital gain (long-term if held over one year)

Example: You exercise 1,000 NSOs at $10 strike when FMV is $50. Your ordinary income is $40,000 (1,000 × $40 spread). You owe income tax plus 15.3% FICA tax on that $40,000 right away. If you sell at $60 six months later, you owe short-term capital gains tax on the extra $10,000.

Read more about NSOs in the IRS Publication 525.

Incentive Stock Options (ISOs)

ISOs are granted only to employees (not contractors or board advisors) and receive preferential tax treatment—if you meet holding requirements.

• When you exercise, there is no immediate tax (though you may trigger the Alternative Minimum Tax, or AMT, in the exercise year)
• If you hold the shares for at least two years from grant date and one year from exercise date, the gain is taxed as long-term capital gain—a much lower rate
• If you sell before meeting the holding period (a "disqualifying disposition"), the spread is taxed as ordinary income

Example: You receive an ISO grant on 1 January 2022, exercise on 1 January 2023 at $10 strike (FMV $50), and sell on 1 January 2024 at $70. No tax at exercise. Because you held for two years from grant and one year from exercise, you owe long-term capital gains tax on only $20,000 (sale price minus original strike price).

ISOs are powerful but come with traps. The AMT can create a big tax bill in the exercise year, even without selling shares. Always consult a tax professional before exercising ISOs in large amounts.

Learn more: IRS Publication 525, Incentive Stock Options.

Restricted Stock Units (RSUs)

RSUs are promises to deliver shares upon vesting. Unlike options, they have value even if the stock price falls.

• When an RSU vests, the FMV of the shares is ordinary income taxable at your marginal rate
• You owe tax on vesting day regardless of whether you sell the shares
• FICA and federal withholding taxes are usually deducted from your salary or cash proceeds
• When you later sell, any gain or loss from the vesting price is capital gain (long-term if held over one year)

Example: You receive 1,000 RSUs at FMV $50 each. On vesting day, $50,000 is ordinary income. Your employer withholds approximately $15,000–$20,000 in federal and FICA taxes. If the stock rises to $70 and you sell, you owe capital gains tax on the $20,000 gain.

RSUs are simpler than options but create a certain tax liability on vesting, regardless of stock performance. Many employees are hit with an unexpected tax bill because they didn't plan for it.

Employee Stock Purchase Plans (ESPPs)

ESPPs let you buy company stock at a discount (typically 10–15% below market price).

• If your plan qualifies under Section 423 (most do), the discount is not taxed when you buy
• When you sell, the discount becomes ordinary income ("bargain element"), and any additional gain is capital gain
• If you hold shares for at least two years from grant date and one year from purchase, the bargain element gets favorable capital gains treatment

Example: Your ESPP offers a 15% discount. You buy 100 shares at $85 (15% off the $100 market price). The $1,500 discount (the bargain element) is ordinary income when you sell. If you held long enough and sold at $120, you also owe capital gains tax on the $3,500 ($120 − $85 cost basis).

ESPPs are often overlooked but can be valuable. The key is to hold long enough to get capital gains treatment on the bargain element.

Federal Income Tax Rates on Equity

Your total tax bill depends on the type of compensation and your income level:

• Ordinary income (NSO spreads, RSU vesting, ESPP bargain elements): taxed at your marginal federal rate, currently ranging from 10% to 37% depending on income
• Long-term capital gains (held over one year): currently 0%, 15%, or 20% depending on income
• Short-term capital gains (held under one year): taxed as ordinary income
• Self-employment / FICA tax: 15.3% on NSO spreads and RSU vesting (only employee portion if you are an employee; full 15.3% if self-employed)

For the current tax brackets and capital gains rates, check IRS Income Tax Brackets and Rates.

State and Local Taxes

Don't forget your state. California, New York, and other high-tax states can add 5–13.3% to your federal bill. Some states (like Texas, Florida, and Washington) have no income tax on equity gains.

If you move states, the taxing rules can be complex. A key question: Did you exercise or vest while living in a high-tax state? Some states claim tax on the spread even if you moved before selling. This is a common trap for founders who leave California or New York.

Exercise & Hold vs. Sell-to-Cover

When you exercise options, you face a choice:

1. Exercise and hold: Pay the tax out of pocket. You keep all the upside but lock in a large cash outflow and capital gains tax risk if the stock falls.

2. Sell-to-cover (cashless exercise): Exercise and immediately sell enough shares to cover the strike price and taxes. You keep some shares and realize immediate short-term capital gains.

3. Net settlement (broker-assisted cashless): Your broker advances the cash, you repay from sale proceeds. Used for RSUs and restricted stock.

Each approach has pros and cons. Exercise-and-hold can minimize short-term capital gains taxes but creates concentration risk. Sell-to-cover is simpler but uses up one-year holding periods, making long-term capital gains treatment harder to achieve.

Planning Strategies

Timing Large Exercises

If you plan to exercise a large amount of NSOs or ISOs, spread the exercise over two tax years if possible. This keeps you out of a higher tax bracket and spreads the AMT impact for ISOs.

ISO Holding Requirements

If you have ISOs and the stock has appreciated significantly, do not sell early unless you have a compelling reason. The difference between long-term capital gains and ordinary income can easily be 15–25 percentage points.

Charitable Donations of Appreciated Stock

If you hold appreciated equity for over one year, donating shares to a qualified charity can be more tax-efficient than selling. You deduct the full FMV and avoid capital gains tax. Discuss this with your tax advisor and your favorite charity.

Tax-Loss Harvesting

If some of your equity positions have fallen below cost, you can sell to realize losses that offset other capital gains or up to $3,000 of ordinary income. Be mindful of wash-sale rules if you repurchase similar stock within 30 days.

Quarterly Estimated Taxes

If you exercise options or expect large equity sales, you may need to pay quarterly estimated taxes to avoid underpayment penalties. Talk to your accountant in January about your plan for the year.

Common Traps and How to Avoid Them

Not withholding enough for RSU vesting. Many employers withhold based only on federal tax, ignoring state and FICA. Budget for the full amount.

Selling NSO shares too soon. If you exercise and sell within weeks, you'll owe short-term capital gains tax on any appreciation. Hold at least one year if possible.

Triggering AMT with ISOs. Exercising large amounts of ISOs in one year can trigger the Alternative Minimum Tax, creating a tax bill with no corresponding cash proceeds. Plan ahead, especially in high-income years.

Ignoring state tax on options exercised out-of-state. If you worked in California or New York when you exercised, those states may claim tax on the spread even if you've since moved.

Not tracking your cost basis. Keep records of every grant date, vesting date, exercise date, and FMV. The IRS expects detailed documentation, and your broker's records may not align with your own.

Working with a Tax Professional

Equity compensation is too important to leave to guesswork. Before you exercise options, vest RSUs, or execute a large sale, meet with a licensed tax professional—a CPA or Enrolled Agent in the US—who understands startup equity. They can model the tax impact, time the transaction to minimize withholding, and flag state and AMT issues.

At Next Tax Source, every equity transaction is reviewed and signed by a licensed CPA or EA. We model multiple scenarios, coordinate with your financial advisor, and ensure you're not blindsided by a surprise tax bill.

Summary

Equity compensation is one of the most valuable—and most misunderstood—parts of a job or founder role. The key takeaway:

• NSOs trigger ordinary income tax on the spread at exercise, plus capital gains on any appreciation
• ISOs defer tax until sale but require careful holding periods to get long-term capital gains treatment
• RSUs create ordinary income tax on vesting day, regardless of stock performance
• ESPPs offer discounts taxed as ordinary income, but long holding periods can convert to capital gains
• State, local, and FICA taxes add material cost
• Timing, holding periods, and withholding decisions can save or cost you tens of thousands of dollars

Don't wait until April to think about equity taxes. Plan in January, stay informed, and consult a licensed professional before you exercise or sell.

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Ready to Optimize Your Equity Taxes?

Equity compensation strategy is complex, but the upside of a clear plan is enormous. Whether you're exercising options, managing an upcoming RSU vest, or planning a major sale, our team of licensed CPAs and EAs can model scenarios, minimize your tax bill, and keep you compliant across federal and state jurisdictions. Book a consultation today, or explore our tax planning services to see how we help founders and executives make smart equity decisions.

Frequently asked questions

Do I owe tax when I receive options or RSUs?

No. You owe tax only when you exercise an option or vest an RSU. The grant itself is not a taxable event.

What's the difference between NSOs and ISOs?

NSOs trigger ordinary income tax on the spread at exercise. ISOs defer tax until sale but offer long-term capital gains rates if you meet holding requirements (2 years from grant, 1 year from exercise). ISOs are only for employees and can trigger AMT.

When do I owe tax on RSU vesting?

On the vesting date, the fair market value of the vested shares is ordinary income. You owe tax that day, typically via withholding from salary or cash proceeds, even if you don't sell the shares.

Can I reduce my tax bill by donating equity to charity?

Yes. If you've held appreciated stock (options exercised long ago, or RSUs held over one year) for over one year, donating to a qualified charity lets you deduct the full fair market value and avoid capital gains tax. Consult your tax advisor and charity for details.

Do I owe self-employment tax on equity compensation?

If you're an employee, you owe FICA tax (15.3% combined, split between you and your employer) on NSO spreads and RSU vesting. If you're self-employed or a contractor with options, consult a tax professional—self-employment tax rules are complex.