Chapter 18: Equity compensation is salary, not a lottery ticket
If your company pays you $30,000 in stock this year, you got a $30,000 raise. Not a lottery ticket, not a loyalty test, not "free money": a raise, paid in shares instead of cash. The households that handle equity compensation well all do the same thing: they treat it like salary. The households that get hurt treat it like a bet they're already winning.
This chapter covers the three common flavors (RSUs, ESPPs, and options) plus the two traps that cost real money: the withholding gap and concentration.
RSUs: cash you haven't sold yet
A Restricted Stock Unit (RSU) is a promise: stay employed until a future date, and the company hands you shares. The date the shares become yours is called vesting, and it usually happens on a schedule, say a four-year grant vesting every quarter.
The tax rule is simple and surprises almost everyone: RSUs are taxed as ordinary wages the day they vest, based on the share price that day. Vest $30,000 of stock, and your W-2 grows by $30,000, exactly as if you'd received a $30,000 cash bonus. What you do with the shares afterward is a separate decision. Sell immediately and there's almost no extra tax, because the shares have barely moved since vest. Hold them, and any further gain or loss is taxed like any other stock you own (the capital-gains rules from Chapter 15).
That leads to the single most useful sentence in this chapter, the cash test: if the company had paid you $30,000 in cash, would you use all of it to buy company stock that day? If the answer is no (and it almost always is), holding your vested RSUs is the same decision wearing a costume.
The withholding gap: the surprise bill in April
Now the trap. When RSUs vest, employers typically withhold federal tax at the IRS flat rate for supplemental wages: 22%. But if equity pushes your income high enough, your marginal rate (the tax rate on your last dollar of income, from Chapter 15) is far above 22%. The IRS doesn't care what was withheld; it cares what you owe.
Watch it happen to Maya, who earns $220,000 in salary plus about $120,000 a year in vesting RSUs, putting her marginal federal rate around 35%:
Federal tax her employer withholds on a $120,000 year of RSU vests.
Roughly what that $120,000 of extra wage income adds to her federal bill.
The gap is about $15,600: a five-figure bill waiting in April, plus possible underpayment penalties, and that's before state tax. Nobody did anything wrong; the default withholding is just too low for high earners. The fix is mechanical: estimate the gap when shares vest, and either set the cash aside in savings, increase withholding on your salary (a new W-4), or pay quarterly estimated taxes. Sell-to-cover at 22% is a down payment, not the bill.
Every time RSUs vest, do two things the same week: set aside the difference between your marginal rate and what was withheld, and apply the cash test to the shares. Withholding is not your tax bill, and holding is not the default; it's a choice.
Maya's vest-and-diversify policy
Selling stock feels disloyal, and choosing in the moment invites second-guessing: it's been going up, maybe just this once I'll hold. The antidote is a written policy, decided on a calm day, executed on autopilot.
Maya holds $460,000 of employer stock against $300,000 in a broad US stock fund and $60,000 in bonds: 56% of her portfolio in one company that also pays her salary. Her written policy, kept in her investment plan from Chapter 14: sell at least 75% of every vest in the first open trading window, with the proceeds going straight to her index funds and her tax set-aside; cap total employer stock at 10% of her investable assets, selling down the existing pile as windows and tax lots allow; and any exception must be written down before the vest date, with a reason and a review date. No exception has survived being written down yet.
The 10% cap isn't magic; some planners use 5%, some 15%. The point is that the number is chosen in advance, and the burden of proof sits on keeping the stock, not selling it.
ESPP: the closest thing to free money at work
An Employee Stock Purchase Plan (ESPP) lets you buy company stock through payroll deductions at a discount, commonly 15%. The arithmetic is better than it sounds: a 15% discount means you pay $85 for a share worth $100, a gain of 15 ÷ 85, or about 17.6%, on the day you buy. Many plans add a "lookback" that uses the lower of the start or end price of the purchase period, which can push the gain higher still.
Capture the discount, then apply the cash test
A near-guaranteed ~17.6% gain over a few months is hard to beat anywhere, which is why maxing the ESPP and selling promptly is a reasonable default for people with the cash flow to spare. Two sentences on the tax labels: a qualifying disposition (hold the shares more than a year after purchase and two years after the offering began) lets part of your profit be taxed at long-term capital-gains rates. A disqualifying disposition (selling sooner) taxes the discount as ordinary wages, which is fine; capturing a sure gain and diversifying usually matters more than the label. Details live in IRS Publication 525.
One caution: your paycheck is reduced for months before the purchase happens. Don't fund an ESPP with money you need for essentials or your reserve (the order of operations from Chapter 4 still applies).
Options: NSOs, ISOs, and the AMT tripwire
A stock option is the right to buy shares later at a fixed strike price set today. If the stock rises above the strike, the spread is your gain; if it never does, the option simply expires. Two tax flavors:
- Non-qualified stock options (NSOs): when you exercise (buy the shares), the spread between strike and market price is taxed as ordinary wages right then. Simple, predictable.
- Incentive stock options (ISOs): no regular tax at exercise, and if you hold long enough (one year past exercise, two past grant), the whole gain can be long-term capital gains. The fine print bites, though.
The AMT trap, honestly
Exercising ISOs and holding the shares can trigger the Alternative Minimum Tax (AMT), a parallel tax calculation that can tax your paper gain at exercise even though you haven't sold a share or seen a dollar of cash. People have owed six-figure tax bills on private-company stock they couldn't sell, watching the shares later fall below the strike price. Before any large ISO exercise, run the AMT math (IRS Topic 427 covers option taxation) or pay a professional for one afternoon; Chapter 26's situations list includes exactly this moment.
Two more option facts that matter more than people expect. First, the post-termination exercise window: most plans give you only 90 days after leaving a job to exercise vested options or lose them. Check yours before you resign, because exercising may require real cash plus a tax bill. Second, private-company paper gains are not cash. Until there's a sale, an IPO, or a tender offer, that dazzling number in your equity portal can't pay rent, and it can go to zero. Never count it in your emergency math, and never borrow against the life it implies.
Concentration: one company, every basket
Diversification (Chapter 13) is about not letting things fail together. Equity compensation quietly stacks everything on one company:
This is why Maya's 56% position is riskier than the same dollar amount in an index fund. If her company stumbles, the stock falls, the unvested RSUs shrink, the job and the insurance attached to it (Chapter 9 covered her disability-coverage discovery) get shakier, all in the same season, exactly when she'd need the money. A layoff plus a 40% stock drop is one event, not two.
Count everything tied to your employer (salary, unvested grants, held shares, ESPP, benefits) as one exposure. Keep the part you can control (the shares you've already received) at or below about 10% of your investable assets, and sell on a written schedule, not a feeling.
Where people go wrong
- Holding every vest by default. It feels like doing nothing; it's actually a large, repeated stock purchase that fails the cash test.
- Trusting the 22% withholding. Estimate your real marginal rate every vest year, or April will estimate it for you.
- Exercising ISOs without an AMT calculation. Paper gains can create real tax bills.
- Letting taxes block diversification. Yes, selling long-held winners costs capital-gains tax (Chapter 15 has the toolkit), but paying 15–24% on a gain beats riding 56% of your wealth through one company's bad decade.
- Spending the grant before it vests. Unvested equity is a forecast, not income. Budget on cash.
Key takeaways
- Equity compensation is salary paid in shares. Apply the cash test: would you buy this stock with a cash bonus today?
- RSUs are taxed as wages at vest, but employers typically withhold only 22% federal; at a ~35% marginal rate, a $120,000 vest year leaves a gap of roughly $15,600. Set it aside yourself.
- A written vest-and-diversify policy (sell most of each vest, cap employer stock near 10%, exceptions in writing before the vest) beats deciding in the moment.
- An ESPP's 15% discount is about a 17.6% gain at purchase, often worth capturing even if you sell immediately.
- ISOs can trigger AMT on gains you haven't received; private-company paper wealth is not cash. Your job, benefits, and equity are one concentrated bet; manage them as one.
Sources: IRS: Topic 427, Stock Options · IRS: Publication 525, Taxable and Nontaxable Income · IRS: Publication 550, Investment Income and Expenses