How Are Employee Stock Options And RSUs Taxed

RSUs are taxed as ordinary income at vesting based on the fair market value of the shares, while the tax treatment of stock options depends on the type: NSOs are taxed at exercise on the bargain element, and ISOs are generally taxed only when you sell the shares, potentially at capital gains rates.

How stock options taxed as income when RSUs vest

When your restricted stock units vest, the fair market value of those shares on that exact date is treated as supplemental wages. Your employer is required to withhold 22% of that value for federal income tax, plus the 6.2% Social Security and 1.45% Medicare taxes. This happens regardless of whether you sell a single share or hold everything. That means your paystub will show a large “gross” amount added to your taxable wages, then deductions for tax withholding. The net will be shares deposited into your brokerage account, or sold to cover taxes. The key number on your W-2 is in Box 12, code V, which reports the total vesting value. The actual income is already included in Box 1 wages. If your employer withholds shares to cover taxes, a common default, you’ll see fewer shares land in your account. You’re still taxed on the full pre-withholding value. The problem arises when your marginal tax rate is higher than that flat 22% supplemental rate. This happens for most people in tech or finance who are in the 32% or 35% brackets.

The messy difference between NSOs and ISOs

Non-qualified stock options trigger ordinary income at the moment you exercise, equal to the spread between the market price and your strike price. That amount is added to your W-2 wages, subject to income tax and payroll taxes, Social Security and Medicare, just like a cash bonus. Incentive stock options, however, bypass payroll taxes entirely at exercise. This is a big win for high earners near the Social Security wage base. But ISOs have a nasty trap: the spread at exercise counts as “income” for the alternative minimum tax, even though it’s not regular taxable income. If your ISO spread is large, falling in the band the IRS sets for AMT preference calculations, you could owe the AMT at a rate of 26% or 28% on that amount. Check the current AMT exemption and phaseout thresholds at IRS.gov. This is why exercising ISOs in January can feel great. By April 15th you might owe a five-figure AMT bill with no cash to pay it, unless you sell enough shares to cover the tax. The AMT credit carried forward can soften the blow in future years. It’s a cash-flow headache many employees underestimate.

Why your W-2 is probably wrong

Most employees look at their W-2 after a year with RSU vesting. They see a Box 1 wage figure that’s much higher than their base salary. The withholding shown in Box 2 is often far below what they actually owe. That’s because the flat 22% supplemental rate is only a starting point. If your true marginal rate is 32%, 35%, or 37%, the gap between what was withheld and what you owe can land in the band the IRS defines for underpayment thresholds. The result for a large RSU grant, where the value falls in the range the IRS updates annually for supplemental wage withholding, can be a significant shortfall. On the option side, exercised ISOs don’t appear on your W-2 at all, unless you sold them in a disqualifying disposition. Your paystub shows zero withholding for that event. The result is that your total tax liability for the year is rarely reflected in what your employer actually deducted. Combine regular wages, RSU income, NSO spreads, and ISO AMT adjustments. You’re expected to make up the difference through estimated tax payments or by increasing your W-4 withholding. Many employees only see this shortfall when they file and face an underpayment penalty.

Capital gains only kick in when you sell

After the ordinary income event, your holding period clock starts ticking. For RSUs, the event is vesting. For NSOs, it’s exercise. For ISOs, it’s the sale. That clock determines whether your final profit is a short-term or long-term capital gain. For RSUs, the clock starts on the vesting date. Sell six months later, and that gain is short-term. Hold for over a year, and it’s long-term. For NSOs, the clock starts at exercise, not grant. The spread is already taxed as regular income. Any gain above that is purely capital. For ISOs, the clock starts at exercise. You must hold for two years from the grant date and one year from the exercise date to get favorable long-term treatment. Sell earlier, and it’s a disqualifying disposition. The spread becomes regular income. The same logic applies to “taxes on investments” in your brokerage account. The holding period is the single biggest factor in whether you pay 0%, 15%, or 20% on your gains. When you sell shares from any of these plans, the cost basis is the fair market value on the vesting or exercise date. Your brokerage’s 1099-B will show that basis correctly, but only if you didn’t transfer shares or have a corporate action that adjusts your basis incorrectly.

One common mistake is treating RSU sales and option exercises as separate from your core investment strategy. If you’re holding a concentrated position in your employer’s stock, the tax drag of short-term gains can be brutal. Short-term gains are taxed as regular income. This is especially painful if you’re already in a high bracket. Meanwhile, the “are employee stock options and rsus taxed” question often leads to confusion about whether selling immediately is better. For most people, selling RSUs at vest and executing NSOs to sell the same day is the simplest way to avoid the AMT trap. This is a cashless transaction. For crypto holdings, the rules mirror stocks but with no wash-sale protection. “Are crypto and digital asset sales taxed” is a follow-up that trips up many employees who fund their brokerage accounts by selling RSUs. And if you’re earning dividends from those shares, “are dividends taxed in a brokerage account” depends on whether they’re qualified. That’s a separate line item from your compensation income.

The biggest takeaway: your paystub withholding is just a prepayment, not a final bill. RSUs are withheld at 22%, plus payroll, but your true rate might be 35%. NSOs are withheld at 22% on the spread. If you’re in the 24% bracket or higher, you’ll owe the difference. ISOs have zero withholding at exercise. You’re entirely on your own for the AMT. The only way to avoid surprises is to calculate your projected liability each quarter and make estimated payments. Alternatively, adjust your W-4 to withhold extra from your base salary. Book a session with a CPA who specializes in equity compensation before your first vesting cliff. Arrive with your last paystub and your brokerage’s cost basis tracker. Skip the generic online calculators. Review your last paystub of the year. If your RSU vesting or option exercise pushed you into a higher bracket, set aside 30-35% of the gross value just to be safe.

Your W-2 is a prepayment receipt, not a final bill, and the gap between the two is a liability you must calculate yourself each quarter because no employer withholds for ISO AMT exposure.

Frequently asked questions

Can I avoid the AMT on ISOs by selling the shares in the same calendar year?

Yes, but only if you sell the shares in the same year you exercise them. This is called a disqualifying disposition. The spread is treated as regular income, which is regular taxable income but not AMT income. The AMT preference disappears. You lose the chance for long-term capital gains treatment.

What happens if my RSU shares drop in value after vesting but before I sell?

You already paid regular income tax on the full vesting value. If the price drops, you have a capital loss. Sell the shares to lock in that loss. It offsets other capital gains or up to $3,000 of regular income per year. You can’t undo the original tax bill. It’s a sunk cost.

Do I owe payroll taxes on ISO exercise if I hold the shares?

No, ISOs are exempt from Social Security and Medicare taxes at exercise, regardless of when you sell. That’s one of their main advantages over NSOs. NSOs are subject to payroll taxes on the spread. If you sell in a disqualifying disposition, the regular income portion is still exempt from payroll taxes. It’s a permanent benefit.

Should I sell RSUs immediately or hold for long-term capital gains?

Immediate sale is usually the better move. The vesting value is already taxed as regular income. There’s no benefit to holding for a lower rate on the initial gain. Any appreciation after vesting is a new capital gain. Sell right away and reinvest in a diversified portfolio. This avoids concentrated risk and simplifies your tax situation.