Equity compensation shows up in an offer letter looking like a bonus — a reward for good work, money you’ll get to enjoy later. And it is. But how and when that equity gets taxed can swing your bill by tens of thousands of dollars, and the defaults your employer applies are almost never optimized for you.
The people who do best with equity comp aren’t the ones who picked the hottest stock. They’re the ones who understood the tax mechanics before the vesting date, not after. Here’s the map.
The problem hiding in your paycheck
Start with the trap almost everyone hits: withholding. When your RSUs vest or you exercise options, your employer typically withholds federal tax at the flat supplemental wage rate — often 22%. If your actual marginal rate is 32%, 35%, or 37%, that gap is real money, and nobody flags it. You find out the following April when you owe far more than you expected.
Underwithholding isn’t a rounding error on a big equity year — it’s the single most common equity-comp surprise we clean up. The fix is boring and effective: plan for the gap and make an estimated payment, rather than letting the default withholding quietly set you up for a penalty.
RSUs: taxed the moment they vest
Restricted stock units are the simplest to understand and the easiest to mishandle. When they vest, the full market value counts as ordinary income that year — whether or not you sell. Your company usually sells a slice to cover taxes (“sell to cover”), but as noted above, that slice is often too small.
Here’s the part people miss: once RSUs vest and you’ve been taxed, holding the shares is a new investment decision, not a continuation of your comp. You’ve effectively already been paid in cash and chosen to buy your employer’s stock with it. If you wouldn’t buy that much of one company’s stock on the open market, holding a big vested position is quietly a concentration bet — one that also happens to sit right next to your paycheck and your job security.
Stock options: the family matters
“Options” isn’t one thing. The tax treatment splits sharply.
Non-qualified stock options (NSOs). When you exercise, the spread between the strike price and the market value is taxed as ordinary income right then, and it’s subject to withholding. Straightforward, but the exercise itself is a taxable event you control the timing of.
Incentive stock options (ISOs). These get the favorable treatment — if you clear the hurdles. Exercising an ISO triggers no regular income tax. But the spread is a preference item for the alternative minimum tax (AMT), and this is where sophisticated people get blindsided: a large ISO exercise can generate a big AMT bill on paper gains you haven’t sold. Clear the holding periods — more than two years from grant and more than one year from exercise — and your eventual sale is taxed at long-term capital gains rates. Miss them, and you’ve turned a capital-gains opportunity into ordinary income.
Warning — the costliest mistake we see
The ISO / AMT trap. A large ISO exercise can create a real, cash-due tax bill on paper gains you haven’t sold a share of — and it surprises people precisely because they thought they were being patient and tax-smart. Model it before you exercise, not after.
ESPP: a discount with strings
Employee stock purchase plans (ESPP) let you buy company stock at a discount — often a genuinely good deal. But the tax depends on how long you hold. Sell too soon (a “disqualifying disposition”) and more of your gain is taxed as ordinary income; hold long enough for a “qualifying disposition” and more of it gets capital-gains treatment. The discount is worth capturing; the holding decision is worth planning.
One more tool: the 83(b) election
If you receive restricted stock (common in startups and early-stage companies), the 83(b) election lets you choose to be taxed on the value now, at grant, rather than as it vests. In a company whose value is climbing, that can convert a large future ordinary-income event into a small one now, with future appreciation taxed as capital gains. The catch: you have just 30 days from the grant to file it, and it can’t be undone. It’s powerful and unforgiving — exactly the kind of decision that shouldn’t be made in the last week of the window.
Know how each one is taxed
Four equity types, four different tax moments, four different traps. This is the whole map:
| Type | When it’s taxed | The main trap |
|---|---|---|
| RSUs | As ordinary income at vesting, on the full value | Default withholding (often 22%) is too low for high earners → April surprise |
| NSOs | Spread taxed as ordinary income at exercise | You control the timing of a taxable event — most people don’t plan it |
| ISOs | No regular tax at exercise; capital gains if you hold long enough | The spread triggers AMT — a tax bill on gains you haven’t sold |
| ESPP | Depends on how long you hold after buying | Selling too soon turns a capital gain into ordinary income |
The three moves that actually save money
Strip away the jargon and equity-comp planning comes down to three recurring decisions:
- Close the withholding gap so a big vesting or exercise year doesn’t become an April penalty.
- Manage concentration — decide deliberately how much of your net worth should ride on one company, and diversify on a schedule instead of by accident.
- Time exercises and sales across tax years — especially around AMT, bracket thresholds, and capital-gains rates — so you’re choosing your tax year instead of letting the vesting calendar choose it for you.
The grant is the easy part. The tax is where the money is won or lost.
The bottom line
The defaults are built for the payroll system’s convenience, not your outcome. If you have RSUs, options, or an ESPP and you’ve been letting the withholding and the vesting calendar make your decisions, you’re almost certainly leaving money on the table — or setting up a surprise.
Want the quick version?
Download our free one-page Equity Comp Tax Cheat Sheet — every equity type, when it’s taxed, and the main trap, on a single page. Then, if you’d like a real plan around your vesting and exercise schedule, let’s talk.
General information for educational use, not tax advice for your specific situation. Equity compensation outcomes depend on your plan documents, holding periods, and overall tax picture.