Stock Options and RSUs: A Tech Employee's Guide to Equity Compensation

If a meaningful share of your compensation comes as equity, you are probably holding some combination of restricted stock units (RSUs), incentive stock options (ISOs), non-qualified stock options (NSOs), and shares from an employee stock purchase plan (ESPP). These four instruments look similar from the outside, but they vest, get taxed, and create decisions in very different ways.

This guide walks through each type, the timing decisions you face, the tax rules that drive most of the math, and the mistakes that cost equity-compensated employees the most money.

The Four Common Types of Equity Compensation

Restricted Stock Units (RSUs)

A grant of company shares delivered to you on a future date once you meet a vesting condition. There is no purchase price. When the shares vest, they are yours.

Most large public tech companies have moved primarily to RSUs because they are simple to administer and always have value, unlike options which can go underwater if the stock falls below the strike price.

Non-Qualified Stock Options (NSOs)

The right to buy a set number of shares at a fixed price (the "strike price") for a set period, typically up to 10 years. To get the shares, you have to exercise the option and pay the strike price.

NSOs are common at private companies and are sometimes used at public companies for executives.

Incentive Stock Options (ISOs)

A special type of stock option with preferential tax treatment, available only to employees and subject to several rules. Like NSOs, ISOs have a strike price and an expiration date.

ISOs are most common at private startups. Per IRS rules on stock options, only $100,000 worth of ISOs (measured at the grant date fair market value) can vest in a single year per employee. Anything over that limit is automatically treated as NSOs.

Employee Stock Purchase Plan (ESPP)

A program that lets you buy company stock through payroll deduction at a discount, typically up to 15% off. Most ESPPs are "qualified" under Section 423 of the tax code, which provides specific tax benefits if you hold the shares long enough.

How Vesting Works

Vesting is the schedule on which you actually earn your equity. Two common structures:

• Graded vesting: A portion vests on a regular schedule, often monthly or quarterly, frequently after a one-year cliff. A common public-company RSU grant might vest 25% after one year, then quarterly over the next three years.
• Cliff vesting: Nothing vests until a single date, then the full amount vests at once. Less common for ongoing grants, more common for special bonuses.

At private companies, you may also see double-trigger vesting on RSUs: shares only vest when both a time condition is met AND a liquidity event (typically an IPO or acquisition) occurs. This was popularized by pre-IPO companies to avoid creating tax bills on illiquid shares employees couldn't sell.

RSUs: The Tax Trap That Catches High Earners

This is where most equity-compensated employees get into tax trouble.

When RSUs vest, the IRS treats the full fair market value as ordinary income, reported on your W-2. Your cost basis is the FMV at vesting, and any gain or loss after that point is treated as a capital gain when you sell.

The trap is in the withholding. Most companies withhold federal taxes at the 22% supplemental wage rate on RSU income (or 37% on supplemental wages above $1 million in a year), and they typically execute "sell to cover" by automatically selling enough shares to cover the withholding.

If your marginal federal tax bracket is 32%, 35%, or 37%, the 22% withheld is far less than what you actually owe. The shortfall is your problem at tax time. High earners with significant RSU vesting often need to make quarterly estimated payments to avoid underpayment penalties.

The "sell at vest or hold" question is also under-appreciated. If you wouldn't take that day's after-tax cash and use all of it to buy your employer's stock, holding the vested shares is the same decision in disguise. You are choosing to hold concentrated stock instead of cash.

NSOs: Income on Exercise

NSOs are taxed on the day you exercise, not the day they vest. The "spread" (FMV at exercise minus the strike price) is taxed as ordinary income.

Example: You have NSOs with a $5 strike and the stock is now worth $50. You exercise 1,000 shares. You owe ordinary income tax on $45,000 of spread, and you also have to pay the $5,000 strike price.

After exercise, your cost basis is $50 per share. Any subsequent gain or loss is a capital gain when you sell, short-term if you sell within a year of exercise, long-term after that.

The main planning lever for NSOs is timing. Exercising in a low-income year (a sabbatical, a year between jobs, or before you take a higher-paying role) can put more of the spread into lower tax brackets.

ISOs: AMT Is the Whole Story

ISOs are the most tax-favored type of equity compensation if you handle them correctly, and the most expensive if you don't.

When you exercise an ISO, there is no regular income tax on the spread. But the spread is an adjustment for the alternative minimum tax (AMT). The IRS uses AMT to make sure high-income taxpayers with large preference items still pay a minimum amount of tax.

If you exercise enough ISOs in a single year, AMT can hit hard, and you owe the tax even if you never sold the shares. The cash to pay the tax has to come from somewhere. The good news is that AMT paid on an ISO exercise generates a credit you can use to offset regular tax in future years, but recovering it can take time.

The other ISO rule that drives planning is the qualifying disposition test. To get long-term capital gains treatment on the entire gain, you have to:

1. Hold the shares for at least 2 years from the grant date, AND
2. Hold the shares for at least 1 year from the exercise date.

If you sell before meeting both, it is a disqualifying disposition. Some or all of the gain is taxed as ordinary income on your W-2 in the year of sale, depending on the price at sale relative to the spread at exercise.

For employees of pre-IPO companies, the planning question is often whether to early exercise ISOs (before they vest, when the strike and FMV are still equal or close), file an 83(b) election within 30 days, and start the long-term capital gains clock years before a liquidity event. This can dramatically lower the eventual tax bill, but you are spending cash on shares that may end up worthless.

ESPP: A Discount With Strings Attached

A qualified ESPP works in offering periods, often 6 or 12 months long, with one or more purchase dates inside each period.

Two features drive most of the value:

• The discount. Up to 15% off the purchase-date price.
• The lookback. The discount is applied to the lower of the price at the start of the offering period or the price at the purchase date. If the stock rose during the period, the lookback can be worth far more than the headline 15%.

The annual contribution limit is $25,000 worth of stock per year, calculated at the offering date FMV.

Like ISOs, ESPP shares have a qualifying disposition test:

1. Hold the shares for at least 2 years from the offering date, AND
2. Hold the shares for at least 1 year from the purchase date.

If you meet both, a portion of the gain (roughly the discount you received) is taxed as ordinary income and the rest as long-term capital gain. If you sell early, more of the gain is taxed as ordinary income.

Whether to hold for the qualifying disposition depends on how concentrated you already are in the stock and your read on the company's prospects. The tax benefit is real, but it is rarely worth losing 30% of the share value waiting for it.

Concentration Risk Is the Quiet Killer

Equity compensation tends to accumulate quietly. RSUs vest. ESPP shares purchase. ISOs sit on the books. Five years in, many tech employees discover that 50% to 80% of their net worth is tied up in a single company's stock.

This is the same risk profile as putting most of your savings into a single stock, with the added wrinkle that your job income is also tied to the same company. If the company has a bad year, your portfolio and your paycheck both suffer at the same time.

A common reference point for diversification is to limit any single stock to no more than 10% to 20% of your investable portfolio. Getting from heavy concentration down to that level usually takes a multi-year sell schedule, often executed through a 10b5-1 trading plan so you can sell during company blackout periods.

What Happens When You Change Jobs

Leaving a company creates a tight set of equity decisions:

• Vested options usually expire 90 days after termination. Some companies have extended this window in recent years, but the 90-day default is still common. If you don't exercise in time, the options are gone.
• Unvested equity is typically forfeited. A few companies allow some acceleration, but most don't.
• Exercising vested NSOs or ISOs requires cash for the strike price, plus (for NSOs) the tax bill. This can be a meaningful out-of-pocket cost at the worst possible time.
• Job offers are not directly comparable on equity. A grant of public-company RSUs is not the same as an option grant at a private company. Each has different probabilities of payout and different tax treatment.

The Most Expensive Mistakes

A few patterns to avoid:

• Treating the 22% RSU withholding as the full tax. It usually isn't, and the shortfall plus penalties show up next April.
• Letting RSUs and ESPP shares accumulate without a plan. Concentration grows silently.
• Exercising a large block of ISOs without modeling AMT. A surprise five- or six-figure tax bill on shares you still own and can't sell is a brutal way to learn this rule.
• Letting options expire after leaving a job. Walking away from in-the-money options is one of the most expensive equity mistakes you can make.
• Selling ESPP shares right at purchase when a small additional hold would have flipped the tax treatment. Sometimes the right move, but worth doing on purpose rather than by accident.

Where to Get Help

Equity compensation planning is technical, and the decisions are often time-sensitive. If your equity is large enough or your situation is complex enough, working with a financial planner who specializes in this area can pay for itself many times over.

The Advice-Only Network is a directory of advice-only planners, including those who specialize in equity compensation. Advice-only planners charge a flat fee, hourly rate, or monthly ongoing fee for advice, and don't manage your money or earn commissions. For a primer on the model, see our guide to what is an advice-only financial planner.