Does a Big Bonus or RSU Vest Trigger the AMT? (w/Examples) + FAQs

This article reflects federal rules and California rules as of June 2026 and covers tax year 2025 (returns filed in 2026), with the 2026 changes flagged where they apply. Tax law changes — confirm current figures before you file.

Quick Answer

No. A cash bonus and a normal RSU vest almost never trigger the Alternative Minimum Tax (AMT) on their own. Both are taxed as ordinary wages, identically under the regular tax and the AMT. The real AMT trigger is exercising and holding Incentive Stock Options (ISOs).

Why Your Big Payday Feels Like an AMT Risk

You just got a large cash bonus, or a big block of restricted stock units (RSUs) vested, and someone warned you about the AMT. The fear is understandable, but it is mostly misplaced — a bonus and an RSU vest are simply wages, and wages are treated the same under both tax systems, so they do not create the “preference income” that the AMT punishes. The thing that does quietly create a giant tax bill is exercising ISOs and keeping the shares, because that creates income the IRS counts only for AMT, not regular tax.

This matters because of timing and cash. An AMT hit from ISOs can arrive in April on stock you never sold and that may have since dropped in value. According to the IRS Statistics of Income, only a small fraction of filers pay AMT in any given year, yet equity-heavy tech employees are wildly overrepresented in that group. Knowing which trigger applies to you is the difference between a calm filing and a five-figure surprise.

💰 Why a cash bonus and an RSU vest are AMT-neutral — and the one rare case where a vest matters.
📊 How an ISO exercise creates “phantom income” and a real worked example with the actual math.
🧾 A line-by-line look at Form 6251 (and California Schedule P) so you can follow your own return.
🔁 How the AMT credit (Form 8801) lets you claw the money back in later years.
⚠️ The 2026 OBBBA change that makes the AMT bite faster for high earners.

The Three “Triggers,” Deconstructed

People lump bonuses, RSUs, and stock options together as “equity comp,” but the AMT treats them in completely different ways. Understanding the difference is the whole game. The AMT is a parallel tax system: you calculate your tax the normal way, then recalculate it under AMT rules that disallow many deductions and add back certain income, and you pay whichever number is higher. Wages flow through both systems identically, so they do not move the needle. Stock options can create income that exists only in the AMT system — and that is where trouble starts.

Below, each trigger gets its own explanation: what it is, the consequence, a real example, the common misconception, and what to do.

Cash Bonus

A cash bonus is ordinary wage income, reported on your W-2 in the year you receive it. It is taxed exactly the same under the regular tax and the AMT — there is no add-back, no “preference,” and no special line on Form 6251. The only AMT-adjacent effect is indirect: a very large bonus raises your total income, and high income can phase out your AMT exemption, which could expose other AMT items you already have. The consequence of ignoring this is mild — you might slightly under-withhold, since bonuses are often withheld at a flat 22% federal supplemental rate while your marginal rate is higher. Maria, a single engineer, gets a $150,000 bonus on top of a $200,000 salary; she owes no AMT from the bonus itself but should check her withholding so she is not short in April. The misconception is that “big income equals AMT” — it does not; type of income matters far more than size. What to do: top up withholding or make an estimated payment if the flat 22% leaves you under-withheld.

RSU Vesting

When RSUs vest, the fair market value of the shares on the vest date is treated as ordinary W-2 wages. Like a bonus, this income is identical under both tax systems, so a routine RSU vest does not trigger AMT. The consequence people fear — a surprise AMT bill — almost never comes from the vest itself; it comes from under-withholding, because employers often withhold federal tax on RSUs at the 22% supplemental rate while a high earner’s real rate is 35% or 37%. David, a single employee, has $400,000 of RSUs vest; that is wages, not an AMT preference, but his 22% withholding leaves a big regular-tax gap he must cover. The common misconception is that “stock equals AMT” — but RSUs are wages, not options, and your cost basis resets to the vest-date value, so selling immediately creates little or no extra gain. What to do: set aside cash for the withholding shortfall and consider selling enough shares at vest to cover it.

ISO Exercise — The Real Trigger

This is the one that bites. When you exercise an Incentive Stock Option and hold the shares past year-end, you owe no regular tax — but you must add the “bargain element” (the stock’s fair market value at exercise minus your strike price) to your AMT income on Form 6251, line 2i. The consequence is brutal: you can owe tens of thousands in AMT on paper gains from stock you have not sold and cannot easily sell. Priya exercises ISOs with a $5 strike when the shares are worth $55; the $50-per-share spread becomes AMT income even though she received no cash. The misconception is that “no sale means no tax” — true for regular tax, false for AMT. What to do: model the AMT before you exercise, and consider exercising fewer shares or doing a same-year “disqualifying” sale to convert the spread into ordinary income and dodge the AMT.

Which Situation Applies to You?

The right section depends on what kind of pay you received and what you did with it. Match yourself to one of these:

You got a cash bonus and nothing else changed → no AMT from it; check withholding only.
Your RSUs vested and you held or sold the shares → still wages, no AMT; check withholding.
You exercised NQSOs (non-qualified options) → ordinary income like wages, no AMT add-back.
You exercised ISOs and sold them the same year (a disqualifying disposition) → the spread is ordinary income, no AMT preference.
You exercised ISOs and held them past December 31 → this is the AMT trigger; read the ISO sections closely.
You exercised ISOs and have very high income (above the exemption phase-out) → highest AMT risk, especially in 2026.

How the AMT Math Actually Works

The AMT runs on Form 6251. You start with your taxable income, add back AMT “preferences” and “adjustments” (like the ISO bargain element), subtract your AMT exemption, then apply the AMT rate of 26% on the first slice of income and 28% above a breakpoint. If that “tentative minimum tax” is higher than your regular tax, the difference is your AMT.

For tax year 2025, the federal AMT exemptions and phase-outs are:

Filing status (2025)	Exemption amount and phase-out start
Single / Head of Household	$88,100 exemption; phase-out begins at $626,350 of AMTI
Married Filing Jointly	$137,000 exemption; phase-out begins at $1,252,700 of AMTI
Married Filing Separately	$68,500 exemption; phase-out begins at $626,350 of AMTI

The 26% rate applies to AMTI (after exemption) up to $239,100 for 2025, and 28% applies above that. Above the phase-out threshold, your exemption shrinks by 25 cents per dollar of extra income for 2025.

A Fully Worked ISO Example (with the Math)

Let’s walk through Priya’s numbers so you can copy the math. Priya is single. In 2025 she exercises 10,000 ISOs with a $5 strike when the shares are worth $55, and she holds them. Her salary is $300,000 with no other adjustments.

Bargain element: ($55 − $5) × 10,000 = $500,000 added to AMT income only.
Regular taxable income (after the 2025 standard deduction of $15,000): about $285,000.
Regular tax on $285,000 (single, 2025 brackets): roughly $72,000.
AMTI: $285,000 + $500,000 bargain element = $785,000.
Exemption phase-out: AMTI of $785,000 exceeds the $626,350 start by $158,650; at 25% that erases $39,663, wiping out her entire $88,100 exemption. So exemption = $0.
AMT base: $785,000 − $0 = $785,000.
Tentative minimum tax: 26% × $239,100 = $62,166, plus 28% × ($785,000 − $239,100 = $545,900) = $152,852. Total ≈ $215,018.
AMT owed: $215,018 tentative − $72,000 regular tax ≈ $143,000 in extra AMT.

Priya owes roughly $143,000 in AMT on stock she never sold. The good news: most of that becomes an AMT credit she can recover in future years through Form 8801, because an ISO exercise is a “deferral item,” not a permanent “exclusion item.”

The AMT Credit — Getting the Money Back

The AMT you pay on an ISO exercise is largely a prepayment, not a permanent loss. Because the ISO bargain element is a deferral item, it generates a Minimum Tax Credit you claim on Form 8801 in later years — but only in a year when you do not owe AMT. Each year you carry forward any unused credit until it is used up. When you eventually sell the ISO shares, your AMT basis is higher than your regular basis (because you already paid AMT on the spread), so the sale produces a smaller AMT gain, which frees up the credit. The misconception is that AMT money is gone forever — usually it is not, but recovery can take years and depends on your future income. What to do: file Form 8801 every year after an ISO exercise so you do not forget the carryforward, and keep your Form 3921 from the employer.

Federal vs. California: Two Separate AMT Systems

If you live in a high-tax equity state, your state may run its own AMT. California is the classic example, and it stacks on top of the federal hit. You must answer “does my state follow this?” separately every time.

System	How ISO income is treated
Federal AMT (Form 6251)	Bargain element added to AMTI; 26%/28% rate; recoverable via Form 8801 credit
California AMT (Schedule P 540)	Same ISO add-back, taxed at a flat 7% California AMT rate on top of federal

California reports ISO and California qualified stock option income on Schedule P (540), line 10. A California ISO holder can face both the federal 26–28% AMT and the state 7% AMT on the same spread, so always model both. Many no-income-tax states (Texas, Florida, Washington, Nevada) impose no state AMT at all — for those residents, only the federal calculation matters.

The 2026 OBBBA Change That Raises Your Risk

Starting in tax year 2026, the One Big Beautiful Bill Act (OBBBA) makes the AMT bite faster for high earners. The exemption amounts stay the same ($88,100 single / $137,000 joint), but two things tighten. First, the phase-out thresholds drop back to 2018 levels — about $500,000 for single filers and $1,000,000 for joint filers, far below the 2025 thresholds. Second, the phase-out rate doubles from 25% to 50%, so your exemption disappears twice as fast. The consequence: an ISO exercise that was safe in 2025 may trigger a larger AMT in 2026 at the same income. What to do: if you plan a big ISO exercise, run the numbers under 2026 rules and consider timing your exercise across calendar years.

Comparison Table: Bonus vs. RSU vs. ISO

Pay type	AMT treatment and why
Cash bonus	Ordinary wages; identical under regular tax and AMT; no add-back
RSU vest	Ordinary wages at vest-date value; no AMT preference; basis resets
NQSO exercise	Spread is ordinary wages; taxed the same both systems; no AMT add-back
ISO exercise (hold)	Bargain element added to AMTI only; the main AMT trigger; credit recoverable
ISO same-year sale	Disqualifying disposition; spread becomes ordinary income; no AMT preference

Mistakes to Avoid

Assuming a big bonus triggers AMT. It does not; you may waste time and money chasing a non-problem while ignoring real withholding gaps.
Confusing RSUs with ISOs. RSUs are wages with no AMT add-back; treating them like options leads to wrong tax estimates.
Exercising and holding ISOs without modeling AMT first. You can owe tens of thousands on stock you never sold and cannot afford the bill.
Forgetting to file Form 8801 in later years. You forfeit recovery of AMT you already paid, sometimes permanently.
Using your regular cost basis when you sell ISO shares. You double-pay tax; you must use the higher AMT basis on the AMT gain calculation.
Ignoring California’s separate 7% AMT. California residents underestimate the true cost of an ISO exercise by a wide margin.
Under-withholding on RSUs at 22%. High earners owe far more than 22%, creating a regular-tax shortfall mistaken for “AMT.”
Exercising late in the year with no exit plan. Holding past December 31 locks in the AMT preference with no time to course-correct.

Do’s and Don’ts

Do model your AMT before any ISO exercise, because the bill can dwarf the cash you receive (which is zero).
Do file Form 8801 every year after paying ISO AMT, because that is how you reclaim the money.
Do track your AMT basis separately, because it lowers your tax when you finally sell.
Do check withholding after a bonus or vest, because flat 22% withholding often leaves a gap.
Do consider a same-year disqualifying sale, because it can convert an AMT preference into ordinary income.
Don’t assume wages cause AMT, because bonuses and RSUs flow identically through both systems.
Don’t exercise all your ISOs at once, because spreading exercises across years can keep you under the exemption phase-out.
Don’t ignore the 2026 OBBBA tightening, because the faster phase-out raises risk at the same income.
Don’t sell ISO shares before checking holding periods, because an early sale changes the tax result entirely.
Don’t rely on TurboTax defaults for big ISO years, because complex AMT often needs a CPA’s review.

Pros and Cons of Holding ISOs Through Year-End

Pro: Starts the clock toward a qualifying disposition, because holding 1 year past exercise and 2 years past grant gets you long-term capital gains.
Pro: Builds AMT basis, because the AMT you pay raises your future cost basis and lowers later tax.
Pro: Generates a recoverable AMT credit, because the exercise is a deferral item under Form 8801.
Pro: Locks in a low strike price, because you capture appreciation at favorable long-term rates if the stock rises.
Pro: Avoids ordinary-income treatment, because a qualifying sale taxes the whole gain at capital-gains rates.
Con: Triggers AMT now, because you owe cash tax on a paper gain with no sale proceeds.
Con: Risks a stock drop, because you can pay AMT on a $55 share that later trades at $10.
Con: Ties up cash, because the AMT bill may exceed any liquidity you have.
Con: Credit recovery is slow, because you only reclaim AMT in years you do not owe AMT.
Con: Adds California 7% AMT, because state residents stack a second tax on the same spread.

What to Do Next

Identify your pay type. Pull your W-2, Form 3921 (ISO exercises), and any vesting statements to confirm whether you hold ISOs at all.
If you only have a bonus or RSUs, check your federal and state withholding and make a Q4 estimated payment by January 15 if you are short.
If you exercised and held ISOs, complete a draft Form 6251 now — do not wait for April — and add California Schedule P if you are a resident.
Set aside cash for any AMT due by the April 15, 2026 filing deadline for tax year 2025; missing it adds penalties and interest.
File Form 8801 in every future year to track and recover the AMT credit.
Call a CPA or tax attorney if your ISO spread exceeds roughly $100,000, your income nears the exemption phase-out, or you live in California — this is exactly the complexity where professional help (typically $400–$1,500 for a return like this) pays for itself.

This article is educational and is not a substitute for advice from a licensed CPA or tax attorney about your specific situation.

FAQs

Does a cash bonus trigger the AMT? No. A cash bonus is ordinary wage income for tax year 2025, taxed the same under regular tax and the AMT, with no add-back on Form 6251. It can only raise AMT indirectly by phasing out your exemption.

Does RSU vesting trigger the AMT? No. RSUs vest as ordinary W-2 wages valued at the vest-date price, treated identically under both tax systems. The “surprise tax” people blame on AMT is usually under-withholding at the flat 22% rate.

What actually triggers the AMT? Exercising and holding ISOs is the most common trigger. The bargain element (fair market value minus strike price) is added to AMT income on Form 6251 line 2i for the year you exercise, even with no sale.

How much is the 2025 AMT exemption? $88,100 for single filers and $137,000 for joint filers for tax year 2025. It phases out above $626,350 (single) and $1,252,700 (joint) at 25 cents per dollar of excess income.

What changes for the AMT in 2026? The phase-out gets faster. For tax year 2026, OBBBA cuts the thresholds to about $500,000 single and $1,000,000 joint, and doubles the phase-out rate from 25% to 50%, exposing more high earners.

Do NQSOs trigger the AMT? No. Non-qualified stock options create ordinary wage income at exercise, taxed the same under both systems. Unlike ISOs, there is no AMT preference add-back for NQSOs.

Can I avoid AMT on my ISOs? Yes, often. Exercising fewer shares, staying under the exemption phase-out, or selling in the same year as exercise (a disqualifying disposition) can avoid or reduce the AMT preference.

Do I get the AMT money back? Usually yes. ISO AMT is a deferral item that creates a Minimum Tax Credit on Form 8801, recoverable in future years when you do not owe AMT. Recovery can take several years.

Does California have its own AMT? Yes. California imposes a separate 7% AMT on Schedule P (540), stacking on top of the federal 26–28% AMT. ISO income appears on Schedule P line 10 for residents.

What form reports the AMT? Form 6251 reports the federal AMT, filed with your Form 1040 by April 15, 2026 for tax year 2025. The recovery credit uses Form 8801, and California uses Schedule P.

Does selling RSUs immediately cause extra tax? Rarely. Your RSU cost basis resets to the vest-date value, so selling right away usually produces little or no capital gain. Any small gain is regular capital gains, not AMT.

When should I hire a professional for AMT? When your ISO spread is large. If the bargain element tops roughly $100,000, your income nears the phase-out, or you live in California, a CPA or tax attorney is worth the typical $400–$1,500 cost.

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