Equity Comp & Higher-Income Filers

Almost everyone who gets their first grant of company stock feels the same two fears. The first is simple bewilderment: "I got RSUs (or options) and I have no idea what I'll owe, or when." The second is scarier, because you've heard the horror story: "someone exercised stock options and got a tax bill they couldn't pay — the AMT nearly bankrupted them." Both fears are real, and both come from the same gap in knowledge — not knowing the exact moment each kind of equity becomes taxable. Close that gap and the fear closes with it.

Here is the whole lesson in one sentence: each type of equity compensation has just one or two "taxable moments," and once you know them, the surprises disappear. An RSU is taxed the day it vests. A stock option is taxed when you exercise it (or, for one special type, only when you sell). Employee-purchase-plan shares are taxed only when you sell. That's it. Everything else — the forms, the withholding, the AMT, the basis — hangs off those moments. We'll take each grant, name its moment, do the real math on real people, and by the end you'll be able to look at any equity event and say, calmly, "here's when it's taxed, here's roughly how much, and here's the one thing I have to do so I don't pay twice."

We'll learn this through three households at the income levels where equity actually shows up. Priya and Raj Malhotra — Priya a software engineer in Seattle earning $185,000 with a pile of RSUs and incentive stock options, Raj a consultant with about $90,000 of self-employment income, filing jointly — are our anchor; you met them in Lesson 32 when Priya's ISO exercise triggered a $22,732 AMT bill, and here we finally teach the equity mechanics that lesson deliberately set aside. Nina Kowalski, a Boston physician earning $310,000, shows the higher-income planning moves — the itemized-deduction cap and the mega-backdoor Roth. And Sam Rivera, a 29-year-old engineer who joined a private startup, carries the riskiest corner of all: illiquid stock, the §83(b) election, and an AMT bomb you have to defuse before it's armed.

Before any specific grant, install the mental model, because it makes everything downstream obvious. Equity compensation is just a way your employer pays you in stock instead of (or on top of) cash. And the tax system asks the same question it asks of any pay: when did you actually receive something of value, and what was it worth then? The answer — the "taxable moment" — is different for each grant type, but there are only a few possibilities, and they're the whole map.

Read the map as two phases that repeat for every grant. Phase one — the compensation moment: at some point the value you received is treated as ordinary income, exactly like salary, and shows up (usually) on your W-2 taxed at your regular rates. Phase two — the investment period: from that moment on, you simply own shares with a cost basis equal to whatever was already taxed, and when you sell you have an ordinary capital gain or loss — proceeds minus that basis, short-term or long-term — the Lesson 26 engine, unchanged. Every grant type is just a different answer to "when is phase one, and how is it measured?"

A restricted stock unit (RSU) is the most common form of equity comp at public companies, and the simplest. It's an employer's promise to give you shares later, once you've stuck around long enough — a promise, not the stock itself, which matters more than it sounds. When the company grants you RSUs, nothing is taxed and you own nothing yet; you just have a schedule. Vesting is the moment the promise is kept: on the vest date, the restriction lapses, the shares become really yours, and — because you've now received something of real value for your work — that's your compensation moment.

RSUs typically vest over three or four years (say, 25% a year, or a chunk each quarter after a one-year "cliff"). Each time a tranche vests, that batch of shares is taxed; the still-unvested batches wait their turn. So a single RSU grant produces a taxable moment on every vest date until it's fully vested. Priya's grant from her employer, Kestrel Software, vests quarterly — and this year one of those tranches is about to land.

When RSUs vest, the rule is clean: the fair market value of the shares on the vest date is ordinary compensation income — the same as if your employer had handed you that much cash and you'd immediately bought the stock. It goes straight into your W-2, Box 1 (wages), and it's subject to income tax, Social Security, and Medicare tax just like salary. This year a tranche of Priya's Kestrel RSUs vests: 1,500 shares, and Kestrel's stock is at $160 on the vest date.

Sit with what that $240,000 is and isn't. It is real income — Priya now owns $240,000 of Kestrel stock she didn't have before, and the tax system quite reasonably taxes it as pay. It is not cash — she received shares, not a paycheck, so the tax on it has to come from somewhere. And critically, it stacks *on top* of her $185,000 salary and Raj's income: this is not a separate little pile taxed gently on its own, it's the top slice of the household's income for the year, taxed at their highest marginal rates. That single fact is the whole reason the next section exists.

Here's the surprise that generates a thousand panicked April emails. When RSUs vest, your employer does withhold tax — usually by selling some of the just-vested shares to cover it ("sell-to-cover") and handing you the rest. So people reasonably assume they're square. But the rate the employer uses is fixed by law, and for most higher earners it's too low.

RSU vest income is a supplemental wage — the same category as a bonus — and for supplemental wages the employer withholds federal income tax at a flat 22% (rising to a mandatory 37% only on supplemental wages above $1,000,000 in a year). Twenty-two percent sounds like plenty. But remember phase two of the mental model: this income stacks on top of everything else, so it's taxed at your marginal rate — and for a household already in the 24%, 32%, or 35% bracket, a flat 22% withholding leaves a gap on every dollar. Watch it happen to Priya.

Priya and Raj's other income already fills the brackets up through the 24% band. So her $240,000 vest doesn't get taxed at some gentle blended rate — it lands on top, filling the rest of the 24% bracket and spilling into the 32% bracket. Run the actual marginal math: about $167,108 of the vest is taxed at 24% ($40,106) and $72,892 at 32% ($23,325), for $63,431 of real federal income tax on the vest. But her employer withheld the flat 22% — just $52,800 (raised by selling roughly 330 of the vested shares). The difference is a $10,631 balance due when she files.

And it's actually a little worse than $10,631, because the same vest interacts with the higher-income surtaxes from Lesson 32: the household's wages now sail past $250,000, so the 0.9% Additional Medicare Tax applies to the excess — and here's the echo, employers only withhold that 0.9% on wages over $200,000 *per employer*, so it too can go under-withheld. We'll keep the headline simple — the income-tax gap alone is $10,631 — but flag that a big vest quietly reaches into all three of the shadow taxes you met in Lesson 32.

Because the shortfall is predictable, it's fixable — you just have to pre-empt it rather than discover it. Two levers, either of which closes Priya's $10,631 gap:

• Extra withholding on Form W-4 (Step 4(c)). Tell your employer to withhold an additional flat dollar amount from each paycheck. If you know a big vest is coming — or just know your bracket is above 22% — ask payroll whether they can withhold RSU income at a higher supplemental rate, or add the shortfall to your W-4 Step 4(c) so it's spread across the year. This is the cleanest fix because it keeps you inside the withholding system (no separate payments to remember).
• Quarterly estimated payments (Form 1040-ES). Send the gap to the IRS yourself in the quarter the vest happens. This is the tool when a vest lands mid-year and there's no time to re-tune withholding. Paying in the same quarter also matters for avoiding the underpayment penalty, which is calculated quarter by quarter (Lesson 11).
• Aim at a safe harbor, not perfection. You don't have to nail the exact number. You avoid the underpayment penalty if your total withholding plus estimates covers at least 90% of this year's tax, or 110% of last year's (for higher earners) — the safe harbors from Lesson 11. Cover a safe harbor and any remaining balance is just a bill you pay in April, penalty-free.

Once the vest is taxed, phase two begins and it's ordinary capital gains from here. Priya's basis in the vested shares is the value already taxed as wages — $160 a share (the vest-date fair market value). When she eventually sells, her gain or loss is simply the sale price minus $160, short-term if she's held a year or less since vesting, long-term after that. If she sells the moment they vest, at $160, her gain is $0 — she's already been fully taxed, as wages. If Kestrel rises to $200 and she sells two years later, she has a $40-per-share long-term capital gain. Ordinary, familiar, Lesson 26.

But here is the single most common — and most expensive — stock-comp mistake, and it's not a mistake you make so much as one the paperwork makes for you. When Priya sells, her broker issues a Form 1099-B reporting the sale. By an IRS rule, brokers are *prohibited* from including the compensation income already taxed on your W-2 in the basis they report for shares acquired after 2013. So the 1099-B's basis box (Box 1e) often shows $0 — or only what she literally paid, which for RSUs is nothing.

See the trap concretely. Say Priya sells a share at $200. The 1099-B shows proceeds $200 and basis $0, so it looks like a $200 gain — but $160 of that "gain" is the vest-date value she *already paid ordinary income tax on.* Report it as the form shows and she pays tax twice on that $160: once as wages, again as a phantom capital gain. Her real gain is only $40. The fix is exactly the broken-arrow repair from the mental model: on Form 8949 she enters the reported (wrong) basis, flags it with code B in column (f), and puts an adjustment in column (g) that raises her basis to the true $160 — so column (h) shows only the real $40 gain. Same move for NSOs, ISOs, and ESPP shares, every time.

Let's read Priya's W-2 the way you'd read your own after a big vest year — not the whole general walkthrough (that's Lesson 13), but the specific boxes where equity comp hides. Her $240,000 RSU vest is already baked into these numbers; the point is to see where, so you can confirm it and set your basis. Here is the top of her Kestrel W-2.

Walk the boxes that carry the equity story:

• Box 1 — Wages, tips, other comp: $425,000. IS: all her ordinary compensation. DOES for Priya: her $185,000 salary plus the $240,000 RSU vest, combined into one wages figure. MATTERS: this is the number that flows to her 1040 as wages — the vest isn't a separate line, it's folded into Box 1, which is exactly why people forget it was taxed here when they later sell.
• Box 2 — Federal income tax withheld. IS: what was sent to the IRS during the year. DOES: includes the flat 22% ($52,800) withheld on the vest via sell-to-cover, plus regular withholding on her salary. MATTERS: this is the "tax was taken out" people trust — and the reason the $10,631 shortfall is invisible until they file.
• Box 3 — Social Security wages: $184,500. IS: wages subject to the 6.2% Social Security tax, capped at the 2026 wage base. DOES: her salary alone already hit the cap, so the RSU adds nothing here. MATTERS: it's why a giant Box 1 can sit next to a modest Box 3 — not an error.
• Box 5 — Medicare wages: $425,000. IS: wages subject to Medicare tax, which has no cap. DOES: carries the full salary-plus-RSU total. MATTERS: this box, over $200,000, is where the 0.9% Additional Medicare Tax gets measured (Lesson 32, Form 8959).
• Box 14 — Other: "RSU 240,000." IS: an optional, informational line employers use for anything noteworthy. DOES for Priya: Kestrel spells out how much of Box 1 was the RSU vest. MATTERS: it's your cross-check — it tells you the vest-date value that becomes your basis, so you can defeat the double-basis trap when the 1099-B shows $0.
• Box 12 (code V, when present). IS: reserved for income from exercising a nonqualified stock option. DOES for Priya this year: blank (she vested RSUs, not exercised NSOs) — but we flag it because it's the box the next section's grant type fills. MATTERS: code V is the tell that NSO exercise income is already in Box 1.

A nonqualified stock option (NSO, also called a non-statutory or NQSO) is a right — not an obligation — to buy company stock at a fixed strike price set when the option was granted. Nothing happens at grant, and nothing happens as it vests (vesting an option just makes it *exercisable*). The taxable moment is exercise: the day you pay the strike price and actually receive the shares.

At exercise, the tax is on the bargain element — the deal you got, measured as the gap between what the shares are worth and what you paid for them: (fair market value at exercise − strike price) × shares. That amount is ordinary compensation income, reported on your W-2 (Box 1, with the amount also flagged in Box 12, code V), and subject to income and payroll tax — just like an RSU vest, just triggered by your choice to exercise rather than by a vest date. Your basis in the shares afterward is the full fair market value at exercise (the strike you paid plus the bargain element you were taxed on), and from there it's ordinary capital gains — the double-basis trap applies here too.

An incentive stock option (ISO) is a tax-favored cousin of the NSO — same idea (buy at a fixed strike), but with a special rule Congress created to reward long-term holding. Priya holds ISOs from Kestrel with a $5 strike, and this year she exercises 6,000 of them when the stock is worth $25, paying $30,000 to buy shares now worth $150,000. If this were an NSO, she'd owe ordinary tax on the $120,000 bargain element right now. But it's an ISO, so the headline rule is: exercising and holding an ISO triggers no regular income tax at all. For the regular tax, she bought some stock, sold nothing, and owes nothing. That's the whole appeal.

And that's where the shadow falls. The Alternative Minimum Tax (AMT) — the parallel tax system from Lesson 32 — refuses to honor the ISO's free ride. It counts that same $120,000 bargain element as income the moment you exercise, on Form 6251, line 2i, even though no cash changed hands and no regular tax is due. Tax professionals call it phantom income: a tax base on value locked inside shares you haven't sold and can't spend. This is the single most common event that drops an ordinary high earner into the AMT — and it's exactly the ambush behind "stock options nearly bankrupted them."

Every time you exercise ISOs, your employer must send you (and the IRS) a Form 3921, "Exercise of an Incentive Stock Option." It's a small form and easy to file away and forget — but it's the form that carries every number driving your AMT and your future basis, so it's worth reading once, carefully. Here is Priya's, for her 6,000-share exercise.

Read all six boxes — none is boilerplate, because two dates and two prices are exactly what the tax rules turn on:

• Box 1 — Date option granted. IS: when Kestrel first gave Priya the ISOs. MATTERS: this starts the clock on the "2 years from grant" holding test that decides whether a future sale is qualifying — so this date isn't trivia, it's one of the two dates that determine her tax when she sells.
• Box 2 — Date option exercised. IS: the day she paid the strike and got the shares. MATTERS: it fixes the year the AMT preference lands, and starts the second clock — "1 year from exercise" — for a qualifying sale.
• Box 3 — Exercise price per share: $5.00. IS: what she paid per share. DOES: this is her regular-tax cost basis ($5 × 6,000 = $30,000). MATTERS: it's the lower of the two numbers whose gap is the bargain element.
• Box 4 — Fair market value per share on the exercise date: $25.00. IS: what a share was worth the day she exercised. DOES: it becomes her AMT basis ($25 × 6,000 = $150,000). MATTERS: this is the number the AMT cares about — the value it taxes even though she didn't sell.
• Box 5 — Number of shares transferred: 6,000. IS: how many shares the exercise produced. MATTERS: it's the multiplier that turns a $20 per-share spread into a $120,000 preference.
• Box 6 — Other than TRANSFEROR (blank). IS: used only if the company whose stock she received differs from the one that granted the option. DOES for Priya: blank, because Kestrel is both. MATTERS: even the empty box has a job — its blankness confirms this is a plain single-company exercise with no complication.

Lesson 32 stopped at the exercise. This is the part it saved for us: what happens when Priya sells the 6,000 shares. The answer hinges entirely on *how long she held them*, and there are two named outcomes. A qualifying disposition is a sale that meets both holding tests — more than 2 years after the grant date AND more than 1 year after the exercise date. A disqualifying disposition is any sale that misses either test. Same shares; two very different tax bills.

Say the shares are now $40 and Priya sells all 6,000 for $240,000. Follow both forks:

• Qualifying disposition (she waited). The entire gain over her actual cost is long-term capital gain: $240,000 − her $30,000 strike-price basis = $210,000 of long-term capital gain, taxed at the preferential 15%/20% rates (plus NIIT). No ordinary income, no ordinary rates. This is the reward the ISO was designed to give — and, as the next section shows, it's also the year her AMT prepayment comes home.
• Disqualifying disposition (she sold too soon). Now the bargain element she dodged at exercise comes back as ordinary income: specifically the lesser of the actual gain or the exercise-date bargain element — here the lesser of ($240,000 − $30,000 = $210,000) and $120,000, so $120,000 of ordinary income (taxed at up to 32–35%), added to her W-2. The remaining $90,000 is capital gain. She's converted $120,000 from the low long-term rate to her top ordinary rate by selling early.

Return to the fear this lesson is dismantling — "the AMT can bankrupt you." The cash hit in the exercise year is real, but the framing is wrong, and the sale is where you see why. Priya's $22,732 AMT wasn't a penalty; it was a prepayment of tax on a gain the regular system will eventually tax anyway, and the code hands most or all of it back through the AMT credit (the minimum tax credit, Form 8801). Lesson 32 introduced it; here's how the *sale* is what releases it, through the two cost bases Form 3921 gave her.

Recall her dual basis: for the regular tax her basis is the $5 strike ($30,000); for the AMT it's the $25 exercise value already taxed there ($150,000). In the year she sells at $40, the regular-tax gain ($210,000) is $120,000 *larger* than the AMT gain ($90,000) — because the AMT already taxed that $120,000 back at exercise. That flip is the trigger: in the sale year her regular tax now exceeds her tentative minimum tax, and the minimum tax credit is released to offset the regular tax on that larger gain. The $22,732 she prepaid comes back.

An Employee Stock Purchase Plan (ESPP) is the friendliest grant of all — a payroll-deduction program that lets you buy company stock at a discount, usually up to 15% off. In a qualified plan (the common kind, under tax code §423), the magic is that nothing is taxed at purchase — not the discount, not anything. The taxable moment is deferred all the way to when you sell. Priya participates in Kestrel's ESPP too, so let's set up her numbers.

Two features make ESPPs generous. First, the lookback: the discount is often applied to the lower of the stock price at the start of the offering period or the price on the purchase date — so if the stock rose, you buy at a discount off the *old, lower* price. Second is that deferral of tax. Priya's plan has a 15% discount with a lookback: the offering-period price was $100, the purchase-date price was $120, so she buys at 85% of the lower $100 = $85 a share. She buys 200 shares for $17,000 — shares worth $24,000 that day. She's sitting on a $7,000 built-in gain, and owes no tax yet.

Like the ISO, the ESPP has a qualifying and a disqualifying disposition, with the same reward for patience — but the formulas differ, so let's work both with Priya's shares. The holding test for a qualifying ESPP disposition is more than 2 years from the offering (grant) date AND more than 1 year from the purchase date. Say she later sells all 200 shares at $130 ($26,000).

• Disqualifying disposition (sold within a year of purchase). The ordinary-income piece is the full discount measured at the purchase date: (purchase-date FMV $120 − $85 paid) × 200 = $7,000 of ordinary income — regardless of what the stock did afterward. That $7,000 is added to her basis, making it $120/share, so the remaining gain is ($130 − $120) × 200 = $2,000 of capital gain (short-term here). Total profit $9,000, split $7,000 ordinary + $2,000 capital.
• Qualifying disposition (held long enough). The ordinary-income piece shrinks to the lesser of the actual gain or the discount measured at the offering date: the offering-date discount is (offering FMV $100 − $85) × 200 = $3,000, the actual gain is ($130 − $85) × 200 = $9,000, so the lesser is $3,000 of ordinary income. Her basis becomes $100/share, and the rest — ($130 − $100) × 200 = $6,000 — is long-term capital gain. Same $9,000 profit, but now only $3,000 is ordinary and $6,000 rides the lower long-term rate.

The ESPP's companion to Form 3921 is Form 3922, "Transfer of Stock Acquired Through an Employee Stock Purchase Plan." Your employer sends it the first time you take title to ESPP shares, and — just like the 3921 — it quietly holds every number you'll need at sale to compute the ordinary and capital pieces and to set your true basis. Here is Priya's.

Read the boxes that matter — notice it gives you *both* fair-market values (offering and purchase), which is exactly what the two disposition formulas need:

• Box 1 — Date option granted (offering date). IS: the start of the offering period. MATTERS: it starts the "2 years from grant" clock for a qualifying disposition — the same role Box 1 plays on the 3921.
• Box 2 — Date option exercised (purchase date). IS: the day the plan bought the shares for her. MATTERS: it starts the "1 year from purchase" clock, the second qualifying test.
• Box 3 — FMV per share on the grant/offering date: $100. IS: the offering-date price. DOES: sets the *offering-date discount* ($100 − $85 = $15/share) used in the qualifying formula. MATTERS: this is the number that makes a qualifying sale cheaper.
• Box 4 — FMV per share on the purchase date: $120. IS: the price the day she bought. DOES: sets the *purchase-date discount* ($120 − $85 = $35/share) used in the disqualifying formula. MATTERS: this is the number a disqualifying sale is stuck with.
• Box 5 — Exercise (purchase) price per share: $85. IS: what she actually paid. DOES: her starting cost basis before any ordinary-income add-back. MATTERS: the anchor for every calculation.
• Box 6 — Number of shares: 200. IS: the multiplier. Box 7 — date legal title transferred; Box 8 — grant-date exercise price (only if it wasn't fixed at grant, else blank). MATTERS: Box 8 is usually blank for a normal lookback plan — its blankness tells you the price was determinable at grant, the ordinary case.

Everything so far assumed a public company, where shares can be sold to raise the cash the tax needs. Now meet Sam Rivera, 29, an engineer who joined Nimbus Robotics — a private, venture-backed startup in Austin — as an early employee. Sam has a big grant of ISOs: 40,000 shares at a $0.50 strike. On paper it's a lottery ticket. In tax terms, it's a landmine, and the danger is a sharper version of Priya's: a phantom AMT bill on shares Sam cannot sell to pay it.

Here's how the landmine arms itself. Startups get a fresh 409A valuation (an official fair-market-value appraisal) periodically, and as the company succeeds, that value climbs. Suppose Sam waits the usual four years to vest, and by then Nimbus's 409A value has risen to $8 a share. If he exercises then, the bargain element is ($8 − $0.50) × 40,000 = $300,000 — a $300,000 AMT preference, out of a job he loves, in a single click. That could mean a five-figure AMT bill. And unlike Priya, Sam can't sell any shares to pay it — Nimbus is private, there's no market, the stock is illiquid. Worse, if Nimbus later stumbles and the value falls, he can owe AMT figured on an $8 valuation while the shares are worth pennies. This exact scenario has genuinely ruined people.

Many startups let you early-exercise — buy your option shares *before* they vest. Pair that with an §83(b) election and you can defuse the AMT bomb before it's armed. Here's the move for Sam, done the day he joins while the 409A value still equals his $0.50 strike.

1. Early-exercise now, at a ~zero spread. Sam pays the strike on all 40,000 shares: 40,000 × $0.50 = $20,000. Because the 409A value is also $0.50, the bargain element is ($0.50 − $0.50) × 40,000 = $0 — so there's no AMT preference and no tax on the exercise. He now holds actual (if unvested) shares.
2. File the §83(b) election within 30 days. An §83(b) election tells the IRS to treat the value of restricted stock as income *now,* at grant/transfer, instead of at vesting. Sam files it (on the standardized Form 15620) within 30 days of the early exercise — the deadline is hard and unforgiving. Because the value equals what he paid, the income he's electing to recognize is ~$0. This locks the AMT measurement at today's ~zero spread, so future appreciation never becomes an AMT preference.
3. Start the long-term clock early. The §83(b) also starts his capital-gains holding period now, at exercise — so if Nimbus succeeds and he sells years later, more of the gain is long-term, and he's on the clock for the qualified-small-business-stock benefits that can exempt startup gains entirely (a Lesson-26 topic). One $20,000 check and one 30-day form convert a future $300,000 phantom-income problem into a today's near-zero event.

Now the honest other side, because the §83(b) is a genuine bet, not a free lunch. Sam has spent $20,000 to buy stock in a company that, like most startups, may fail. If Nimbus goes to zero, that $20,000 is gone — he's converted cash into a worthless private stock, and his loss is limited to what he paid (a capital loss of $20,000, no tax refund for the risk). The §83(b) is *irrevocable.* And the classic §83(b) horror story is worse: if you elect on stock worth *more* than you paid, you pay real tax now on that value, and if you later forfeit the shares or the company folds, that tax is never refunded — you paid tax on income you ultimately never received. Sam's version is mild only because he exercised at a ~zero spread; the danger scales with the spread.

Equity events don't happen in a vacuum — a vest or exercise or sale can be the thing that pushes you across the thresholds of the higher-income taxes from Lesson 32. You don't need to re-learn them; you need to know which equity dollar draws which surtax, because they never touch the same dollar and the answer is tidy.

So Priya's $240,000 RSU vest is wages — it draws the 0.9% Additional Medicare Tax on the household's earnings over $250,000, not the NIIT. When she later sells shares at a gain, that gain is net investment income — it draws the 3.8% NIIT, lifting her effective long-term rate from 15% toward 18.8%. The ISO exercise itself draws neither (it's purely an AMT item). The elegant part, straight from Lesson 32: the same dollar is never hit by both — earned income gets the 0.9%, investment income gets the 3.8% — so a big equity year can owe all three shadow taxes at once without any double counting, and Form 8959 and Form 8960 keep them in their lanes.

Now a rule that a blockbuster equity year can wake up — the 2/37 itemized-deduction cap, new for 2026 under the One Big Beautiful Bill Act. It's a quiet haircut on itemized deductions for people in the very top bracket, and it's worth knowing precisely because an equity windfall is exactly what can lift you into its reach. Meet Nina Kowalski, our Boston physician earning $310,000, who itemizes — state and local taxes up to the $40,000 SALT cap, mortgage interest, charitable gifts.

The mechanic: for a taxpayer whose income reaches the 37% bracket, the value of itemized deductions is reduced by 2/37 (about 5.4%) of the lesser of your total itemized deductions or the amount of your taxable income above the 37%-bracket threshold. The effect is to cap the benefit of an itemized dollar at about 35 cents instead of the full 37 — a deliberate trim at the top. The 37% threshold for 2026 is $640,600 for a single filer and $768,700 for a married couple.

Here's the honest part for Nina: at $310,000, the cap doesn't touch her. Her taxable income (after her itemized deductions) is well under $640,600, so the amount "above the 37% threshold" is zero, and 2/37 of zero is zero. That's the first thing to know — for most high earners, this cap is a non-event. But watch what a big equity year does: if a large NSO exercise or a disqualifying ISO sale added a few hundred thousand of ordinary income, pushing her taxable income over $640,600, the cap switches on. A top-bracket single filer with, say, $740,600 of taxable income and $50,000 of itemized deductions loses 2/37 × $50,000 = about $2,703 of deductions — roughly $1,000 of extra tax. Small, but it's one more thing a windfall year quietly triggers.

The other side of higher-income planning is offense: getting more money into a Roth (after-tax in, tax-free growth and withdrawal — Lesson 24) when your income is too high for the front door. High earners are shut out of directly contributing to a Roth IRA, but two side doors remain, and the bigger one is the mega-backdoor Roth. Nina, maxing out and looking for more tax-advantaged room, is the natural user.

It works only if your employer's 401(k) plan allows two things: after-tax (non-Roth) contributions and either in-plan Roth conversions or in-service withdrawals. If so, the mechanic exploits the fact that the total that can go into a 401(k) from all sources in 2026 — the §415(c) limit — is $72,000, far above the $24,500 you can defer yourself. The gap is room for after-tax dollars you then convert to Roth:

The smaller side door is the ordinary backdoor Roth — contribute to a nondeductible traditional IRA (the $7,500 2026 limit) and convert it to a Roth, tracking the basis on Form 8606. It's the move for both Nina and, per their plan, Priya & Raj, all of whom earn past the direct-Roth limits. One caution to carry from Lesson 24: the pro-rata rule — if you hold other pre-tax IRA money, a backdoor conversion is taxed proportionally, so it's cleanest when you have no other traditional IRA balances. The mega-backdoor, running through the 401(k), sidesteps that.

Equity comp has a state dimension that's easy to miss, because the taxable moment can fall years and states away from where you earned the grant. Two threads to hold. First, the state where you worked while the equity was being earned generally gets to tax it, even if you've since moved — states "source" RSU and option income to the workdays between grant and vest (or exercise). Move from a high-tax state to a no-tax one and sell, and the old state may still claim a slice of the vest that accrued there. Multi-state equity is genuinely complex; a big move in an equity-heavy career is a reason to get help.

Second, Priya's home state is a useful case. Washington has no personal income tax, so her $240,000 RSU vest and her salary face no state income tax at all — a real advantage. But Washington layers on a 7% capital-gains excise tax on large long-term gains above an annual exclusion (about $278,000 for 2025, cross-referenced in Lesson 12). Her ordinary equity income is untouched by it, and her share sales are only reached once long-term gains clear that high exclusion — so for most of her equity it's a non-issue, but it's the kind of state-specific wrinkle worth checking rather than assuming.

Step back and the whole lesson reduces to a short set of decisions, each anchored to a taxable moment. This is the checklist to carry:

1. Name the moment. For any grant, ask when it's taxed: RSU at vest, NSO at exercise, ISO exercise creates an AMT preference (regular tax waits for the sale), ESPP at sale. That tells you when the bill lands.
2. Cover the withholding gap. If a vest or exercise creates ordinary income, remember the 22% supplemental rate under-withholds you — add W-4 withholding or an estimate so April isn't a shock. Priya's gap was $10,631.
3. Model the AMT before exercising ISOs — always. The preference is (value − strike) × shares, knowable before you click. Run the two-column calculation (or have a pro run it) so a $22,732 bill is a number you chose, not a surprise. For illiquid startup stock, this is life-or-death for your finances — consider early exercise + §83(b) while the spread is near zero.
4. Decide qualifying vs. disqualifying with the calendar. Holding ISO or ESPP shares past the 2-years-and-1-year lines moves income from ordinary to long-term rates and, for ISOs, is the year your AMT credit returns. Know your two dates.
5. Add the taxed amount to your basis at every sale. The 1099-B will understate your basis; adjust it on Form 8949 so you never pay twice. This one habit saves the most money of anything here.
6. Layer in the higher-income rules. A big year draws the 0.9% and 3.8% surtaxes, may trip the 2/37 itemized cap, and opens the mega-backdoor Roth. Model the whole picture, not just the equity line.

Equity compensation attracts a specific set of dangers — some are honest mistakes the system almost sets you up to make, and one is a genuine predator. Know the four tells, and the one rule that neutralizes all of them.

• 1 · THE RSU UNDER-WITHHOLDING SURPRISE. TELL: a big vest, tax "was withheld," and a shocking balance due in April. It's not a scam — it's the 22% flat rate meeting your higher marginal rate — but it blindsides people every year. The fix is Section 6: extra withholding or an estimate.
• 2 · EXERCISING ISOs WITH NO AMT PLAN. TELL: you exercise a big block, hold the shares, and discover a phantom AMT bill with no cash behind it — especially brutal on illiquid startup stock that later crashes, where you can owe tax on a value that has since evaporated. This has genuinely sunk people. The fix: model the AMT before you exercise.
• 3 · DOUBLE-COUNTING BASIS ON THE SALE. TELL: the broker's 1099-B shows $0 (or too-low) basis, so you over-report the gain and pay tax twice on income already on your W-2. Not fraud — a reporting rule — but it silently overcharges careful people. The fix: adjust basis on Form 8949 (code B), using your W-2, Form 3921, or Form 3922.
• 4 · "EXERCISE NOW, WE'LL FINANCE YOUR TAXES" PROMOTERS. TELL: an outfit urges you to exercise a large block immediately and offers to lend you the money for the tax, or pitches an exotic structure to "erase" the AMT. These push you into a huge taxable event on their timeline, loaded with fees and risk, and the "AMT elimination" schemes are the kind of abusive shelter the IRS actively pursues. The fix: a fee-only professional who models your exercise has no incentive to rush you.

How to report a promoter or abusive scheme — and it's safe to

• WHERE. Report a promoter of an abusive tax scheme (an "AMT elimination" structure, a sham to disguise equity income) to the IRS on Form 14242 (Report Suspected Abusive Tax Promotions), and a preparer who mishandled your equity on Form 14157. A fraud tip goes on Form 3949-A.
• WHAT TO HAVE READY. The promoter or firm's name and materials, what they pitched, any fees, and copies of the forms or filings they prepared. You don't need proof it's illegal — just what you saw.
• WHY IT'S WORTH IT. These schemes target exactly the people who just came into equity and are anxious about the tax. Reporting protects the next person, and — importantly — you are not in trouble for having been pitched; being a target is not a failure.

Maybe you're reading this *after* the surprise — the balance due already landed, or you exercised ISOs last year and only now understand the AMT, or you realize you may have double-counted basis on a sale. Set the self-blame down. The equity-comp rules are genuinely among the most confusing corners of the whole tax code, they interlock with the AMT and the surtaxes, and the paperwork actively works against you (a 1099-B that hides your basis is not your fault). Almost everyone who deals with equity hits one of these at least once. Here's what you can still do.

• An ISO exercise created an AMT bill you didn't expect → remember it's largely a prepayment, not a penalty: it becomes an AMT credit (Form 8801) that comes back in later years, and it fully releases when you sell the shares. Track it — don't write it off as lost.
• You owe a balance you can't pay all at once → you can pay the IRS over time. A short-term plan or an installment agreement (Lesson 38) keeps you in good standing; the bill is manageable, not a catastrophe.
• You double-counted basis and overpaid on a stock sale → you can amend. File Form 1040-X (Lesson 34) with a corrected Form 8949 that adds back the already-taxed amount, generally within three years of filing — and get the overpayment refunded.
• You missed a §83(b) window → this one truly can't be undone, so don't spend energy on it; focus forward on managing the vests and the AMT with the tools above. And going forward, calendar every 30-day window the day you sign.
• You have years of messy equity you never reported cleanly → reconstruct from your W-2s, 3921s, 3922s, and brokerage records, amend the open years, and get current. It's boring and forgiving work, and it closes the anxiety.

Report a predatory promoter for the next person if one was involved (Section 24), and then let it go. One overpaid bill or one missed election is a setback, not a verdict — and now you have the map to keep it from happening again.

Equity comp is the clearest case in personal finance for getting a professional involved *before* the event, not after — the decisions are high-dollar, time-sensitive, and hard to reverse. Here's the ladder, cheapest and most self-serve first, climbing only as far as you need.

1. Your employer's stock-plan resources. The plan administrator (Fidelity, Schwab, E*TRADE, Carta, and the like) has your grant details, vest dates, and the 3921/3922 forms, and often free educational tools. Start here for the facts of your own grants.
2. IRS equity-comp pages and publications. Free and authoritative: Publication 525 (taxable income, including RSUs, options, and ESPPs), the instructions to Forms 6251, 3921, 3922, and 8949, and Tax Topic 427 (stock options). This is where the rules in this lesson come from.
3. A CPA or CFP who models equity comp before you exercise. For a real decision — a big ISO exercise, an 83(b), a concentrated position — pay a fee-only professional to run the two-column AMT calculation and the multi-year plan *before* you act. This is the single highest-value dollar in the whole subject.
4. Amend for basis errors. If you already overpaid by double-counting basis, a preparer can file Form 1040-X (Lesson 34) to fix it and recover the money — generally within the three-year window.
5. The Taxpayer Advocate Service (TAS). If an equity-driven balance, notice, or AMT issue with the IRS becomes a genuine hardship or gets stuck, TAS (Form 911, 1-877-777-4778) is the free, independent backstop inside the IRS.

The real questions people bring to their first equity year, answered in a line and pointed at the section with the full story.

• "My RSUs vested and tax was withheld — why do I still owe more?" Because the flat 22% supplemental rate is below your marginal rate; the vest stacks on top of your income and is taxed higher. Cover the gap with withholding or an estimate (Sections 5–6).
• "I exercised ISOs and sold nothing — why is there a tax bill?" The regular tax says $0, but the AMT counts the bargain element as phantom income. It's real cash in the exercise year, and it largely comes back later as a credit (Sections 10, 13).
• "Should I exercise and hold, or exercise and sell?" Holding past 2 years from grant and 1 year from exercise makes an ISO gain all long-term and releases the AMT credit; selling sooner turns the bargain element into ordinary income. It's a calendar decision (Section 12).
• "Should I make an §83(b) election?" Only on actual restricted stock (or early-exercised options), never on RSUs, and only within 30 days. It shines for startup stock exercised at a near-zero spread; the risk is losing what you paid if the company fails (Section 18).
• "The 1099-B says my basis is $0 — is that right?" No — your basis is at least the amount already taxed as wages (the vest or exercise value). Add it back on Form 8949 or you'll pay tax twice (Section 7).
• "What's the difference between an ISO and an NSO again?" An NSO is taxed as ordinary income at exercise, period. An ISO isn't taxed for the regular tax at exercise but creates an AMT preference, and can qualify for all-long-term treatment if you hold (Sections 9–12).
• "Do I owe the 3.8% or the 0.9% surtax on my equity?" Ordinary equity income (RSU vest, NSO/ISO-disqualifying) draws the 0.9% Additional Medicare Tax; capital gains on selling shares draw the 3.8% NIIT. Never both on the same dollar (Section 19).
• "I got a Form 3921 (or 3922) — do I do anything with it?" Not immediately — it's informational — but keep it permanently. You'll need its boxes to compute your gain and basis correctly when you sell (Sections 11, 16).
• "Can I get more into a Roth if I'm a high earner?" Yes — the backdoor Roth (nondeductible IRA → convert) and, if your plan allows, the mega-backdoor Roth (after-tax 401(k) up to $72,000 total, then convert). (Section 21).
• "My company is private and I can't sell — how do I pay the tax?" This is the danger. For ISOs, plan the AMT before exercising and consider early exercise + 83(b) while the spread is near zero; never exercise a big illiquid block blind (Sections 17–18).
• "Will an equity windfall raise my other taxes?" It can — a top-bracket year can trip the 2/37 itemized cap and intensify the AMT phase-out and surtaxes. Model the whole return, not just the equity line (Sections 19–20).

Everything in this lesson reduces to sorting an equity event into its taxable moment and pricing it — ordinary income now, or an AMT preference, or a deferred sale — and remembering the basis. Here it is as a tool. Pick the event type (RSU vest, NSO exercise, ISO exercise, or ESPP), enter the shares and prices and your filing status and income, and read the tax with the arithmetic shown. It opens on Priya's $240,000 RSU vest; press the presets to watch her ISO exercise produce the $120,000 AMT preference and her ESPP purchase set up its discount.

Play with the edges, because that's where the intuition lives. Turn the RSU vest larger and watch the withholding gap widen as it climbs into higher brackets. Switch to ISO mode and see the same spread that was $0 tax for the regular system become a full AMT preference — then flip to NSO and watch that identical spread become ordinary income taxed right now. Change the ESPP holding period and see income slide from ordinary to long-term. The taxable moment changes everything; your job is only to know which one you're in.

• Restricted stock unit (RSU) — an employer's promise to give you shares once they vest; taxed as ordinary income equal to the shares' fair market value on the vest date.
• Vesting / vest date — the moment restrictions lapse and equity becomes really yours; for an RSU it's the taxable moment, for an option it's when the option becomes exercisable.
• Nonqualified stock option (NSO/NQSO) — an option taxed as ordinary income at exercise on its bargain element; reported on the W-2 (Box 1, flagged Box 12 code V).
• Incentive stock option (ISO) — a tax-favored option that creates no regular tax at exercise, but whose bargain element is an AMT preference; can qualify for all-long-term treatment if held long enough.
• Bargain element — the spread an option gives you: (fair market value at exercise − strike price) × shares. Ordinary income for an NSO; an AMT preference for an ISO.
• Strike (exercise) price — the fixed price at which an option lets you buy the shares, set at grant.
• Qualifying disposition — a sale meeting the holding tests (ISO: >2 years from grant AND >1 year from exercise; ESPP: >2 years from offering AND >1 year from purchase), which maximizes long-term capital-gain treatment.
• Disqualifying disposition — a sale that misses those holding tests, turning more of the gain into ordinary income.
• Employee Stock Purchase Plan (ESPP) — a payroll program to buy company stock at up to a 15% discount; taxed only at sale, with the discount split between ordinary income and capital gain.
• Lookback — an ESPP feature that applies the discount to the lower of the offering-date or purchase-date price, sweetening the deal when the stock rises.
• Form 3921 — the information return your employer sends for each ISO exercise (grant date, exercise date, strike, exercise-date FMV, shares); it holds the numbers that drive the AMT and your basis.
• Form 3922 — the information return for the first transfer of ESPP shares (offering- and purchase-date values, price paid, shares); it holds the numbers for both disposition calculations.
• §83(b) election — a choice to be taxed now, at grant/transfer, on restricted stock (or early-exercised option shares) instead of at vesting; filed on Form 15620 within 30 days, it starts the long-term clock. Not available for RSUs.
• Supplemental-wage withholding — the flat 22% federal withholding on bonuses and equity income (37% above $1,000,000 a year); it under-withholds anyone whose marginal rate is higher.
• Sell-to-cover — the common way employers withhold on a vest: they sell just-vested shares to raise the tax and give you the rest.
• Double-basis (basis adjustment) trap — the broker's 1099-B omits the equity-comp income already taxed as wages, so you must add it back on Form 8949 (code B) to avoid paying tax twice.
• Dual basis (ISO) — the two cost bases an exercised-and-held ISO carries: the strike price for the regular tax, the higher exercise-date value for the AMT; the gap is what releases the AMT credit at sale.
• AMT preference / AMT credit — an ISO bargain element is added to income for the Alternative Minimum Tax (Lesson 32); because it's a timing item, the AMT you pay becomes a minimum tax credit (Form 8801) that returns in later years.
• 2/37 itemized cap — a 2026 rule reducing itemized deductions by 2/37 of income in the top 37% bracket, capping their benefit at about 35 cents on the dollar; it bites only above $640,600 single / $768,700 married.
• Mega-backdoor Roth — putting after-tax 401(k) money (up to the $72,000 total 2026 limit, minus your deferral and any match) into the plan and converting it to Roth; a high earner's way to add large tax-free savings.