AMT Tax Planning: ISO Exercises, Phantom Income, and the Credit You Can Recover

Here is how AMT surprises Bay Area tech workers every year. You exercise 10,000 incentive stock options. Your strike price is $2. The latest 409A valuation puts the stock at $9. You made $70,000 in paper profit. You paid nothing for it yet because you have not sold the stock. In April, your CPA tells you that you owe $19,600 in alternative minimum tax on income you never received as cash. The company has not gone public. There is no liquidity. But the IRS wants a check.

This is not a rare edge case. This is the standard AMT story for tens of thousands of Bay Area startup employees every year. The alternative minimum tax system was designed in 1969 to make sure high-income taxpayers could not zero out their tax liability through preferences and deductions. ISO exercises became collateral damage. Understanding how AMT works, how to model it before you exercise, and how to recover the AMT credit in future years is one of the highest-value planning conversations a Bay Area tech worker can have with a CPA.

Silicon Valley Tax specializes in ISO AMT planning for startup employees, pre-IPO company workers, and established tech executives throughout the Bay Area. Our office is at 2051 Junction Ave, San Jose. Call (408) 383-9870 or book a complimentary consultation to talk through your specific situation before your next exercise.

How the Alternative Minimum Tax Works (IRC Sections 55 Through 59)

The AMT is a parallel tax system that runs alongside the regular tax system. Every year you compute your tax twice: once under the regular rules and once under the AMT rules. You pay whichever amount is higher. AMT sits at the center of the equity-comp tax stack; the full 2026 picture across RSUs, ISOs, ESPPs, and post-OBBBA QSBS is in our Bay Area Tech Compensation Tax Guide 2026.

Under IRC Section 55, the AMT is imposed at two rates: 26% on the first $232,600 of alternative minimum taxable income (AMTI) above the exemption amount, and 28% on AMTI above that threshold (2025 figures for married filing jointly). The exemption itself is $137,000 for married filing jointly in 2025 and phases out at $5 for every $10 of AMTI above $1,237,450. At high income levels the exemption is fully phased out, meaning the full 26%/28% rate applies from the first dollar of AMTI.

IRC Section 56 and IRC Section 57 define the adjustments and preferences that go into AMTI. The ISO exercise spread is an AMT preference item under Section 56(b)(3). When you exercise an ISO and the fair market value exceeds your exercise price, that spread is added back to your income for AMT purposes. The critical distinction: for regular federal income tax, the ISO exercise is not a taxable event. For AMT, it is as if you received ordinary income on the exercise date.

IRC Section 59 covers the AMT credit and other special rules. The AMT credit (Form 8801) is the mechanism that prevents double taxation over time by allowing you to recover AMT paid on timing differences like ISO exercises.

AMT Exemption and Phase-Out Amounts, 2023 Through 2026

The AMT exemption amount and the income level at which it starts to phase out change every year with inflation, and the One Big Beautiful Bill Act (OBBBA), signed in 2025, changed the phase-out mechanics starting in 2026. The table below lines up the four most recent years.

Year	Single Exemption	MFJ Exemption	Phase-Out Start (Single)	Phase-Out Start (MFJ)
2023	$81,300	$126,500	$578,150	$1,156,300
2024	$85,700	$133,300	$609,350	$1,218,700
2025	$88,100	$137,000	$626,350	$1,252,700
2026	$90,100	$140,200	$500,000	$1,000,000

The 2026 exemption amounts are higher than 2025's, and under Section 70107 of OBBBA they are now permanent instead of scheduled to revert to pre-2018 levels. Look closely at the phase-out start column, though. It drops sharply in 2026, from $626,350 to $500,000 for single filers and from $1,252,700 to $1,000,000 for joint filers. OBBBA also raised the phase-out rate from 25 cents to 50 cents per dollar of AMTI above the threshold. The net effect: a taxpayer with AMTI comfortably above these thresholds loses exemption faster in 2026 than in 2025, even though the starting exemption number went up. That matters directly for a large ISO exercise, since the exercise-year AMTI spike from the spread can now cross into phase-out territory at a lower income point than it would have under 2025 rules.

ISO Exercises: The Primary AMT Trigger for Bay Area Tech Workers

Incentive stock options are governed by IRC Section 422. The key statutory benefit is that you do not recognize ordinary income when you exercise an ISO, and if you hold the shares for the required holding period (more than two years from grant and more than one year from exercise), your eventual gain on sale is long-term capital gain.

That benefit is real. But IRC Section 56(b)(3) claws it back for AMT purposes by treating the ISO spread as an AMT adjustment. So you get the federal income tax deferral at the cost of the AMT hit in the exercise year.

The Anatomy of an AMT Bill on an ISO Exercise

Consider a Bay Area engineer at a Series C startup with the following facts:

• W-2 income: $240,000
• RSU vest income already included in W-2: $45,000
• ISO exercise: 20,000 shares, strike price $1.50, current 409A FMV $8.00
• AMT preference item from ISO: 20,000 x ($8.00 - $1.50) = $130,000
• Married filing jointly, two children

Under the regular tax system, taxable income is approximately $240,000 (assuming standard deductions and the RSU already in W-2). Regular tax is roughly $42,800 after credits. No ISO exercise income shows up here.

Under the AMT system, AMTI is $240,000 plus $130,000 ISO preference minus the $137,000 exemption (partially phased out at this income level, let's say it reduces to $112,000) = $258,000 of AMTI. AMT on $232,600 at 26% = $60,476. AMT on the remaining $25,400 at 28% = $7,112. Total tentative minimum tax: $67,588. Less regular tax credit: $42,800. Net AMT owed: $24,788.

That $24,788 is a check due April 15, arising from 20,000 shares that have not been sold and for which there may be no current liquidity market. This is not a theoretical risk. This is a recurring April situation for Bay Area startup employees who exercised options the prior year without modeling the AMT first.

California AMT: What Actually Applies to Bay Area Tech Workers

California still imposes an individual alternative minimum tax. It is one of four states (California, Colorado, Connecticut, Minnesota) with an active state AMT layer as of 2026. Bay Area tech workers exercising ISOs need to run a California AMT projection alongside the federal Form 6251 calculation, not skip it. The California individual AMT rate is 7% on the excess over the current-year exemption on Schedule P (Form 540). The exemption phases out at higher income levels; check the current Schedule P instructions from the California Franchise Tax Board for the year you are modeling.

Layered on top of the AMT question, California does not conform to the federal ISO tax treatment for regular income tax purposes. For federal regular tax, an ISO exercise is not a taxable event. California does not follow this rule. California treats the ISO spread as ordinary income at exercise, like a nonqualified stock option (NSO). The spread is subject to California income tax at up to 13.3% in the year of exercise, and your employer should withhold California income tax accordingly.

The California tax creates a compensating basis step-up when you later sell the shares: your California basis is the FMV at exercise, while your federal basis is the strike price (or the FMV if you paid federal AMT). This basis difference must be tracked and reconciled on Schedule D each year. It is one of the most common errors we find on self-prepared or under-specialized returns.

State AMT Considerations

California is not the only state with its own AMT layer on individuals. As of 2026, four states impose an individual-level alternative minimum tax: California, Colorado, Connecticut, and Minnesota. Wisconsin repealed its individual AMT starting with the 2019 tax year, and Iowa repealed its individual AMT effective 2023 as part of House File 2317 (2022). If you exercise ISOs while living in, or maintaining tax residency in, one of the four remaining states, the state-level computation needs to run alongside the federal Form 6251 projection, not as an afterthought.

State	Individual AMT?	Notes for ISO holders
California	Yes (Schedule P, Form 540)	Rate up to 7%. Also does not conform to the federal ISO deferral rule, so the spread is separately taxed as ordinary income at exercise, apart from the state AMT computation itself.
Colorado	Yes	Colorado imposes a 3.47% AMT on the excess of Colorado tentative minimum tax over normal Colorado income tax, computed on Form DR 0104AMT.
Connecticut	Yes	Applies to residents and part-year residents with federal AMT preference items, including the ISO spread.
Minnesota	Yes	Also layers a 1% surtax on net investment income above $1 million, separate from its AMT, which can stack with an ISO-driven AMT year.

A client who relocates mid-year between two AMT states, or between an AMT state and a non-AMT state, needs the ISO exercise timed around the residency change, not just the calendar year end. We run the state computation and the federal computation together before recommending an exercise date for any client with multi-state exposure.

AMT Timing Strategies for Bay Area Tech Employees

The single most powerful AMT planning tool is timing. The AMT is computed at the end of each calendar year based on that year's income and preferences. By controlling when you exercise ISOs, you can manage the AMT exposure across multiple years rather than concentrating it in a single large hit.

Strategy 1: Exercise in Low-Income Years

The AMT exposure on an ISO exercise is determined partly by your other income. If you have a year with lower W-2 income, no bonus, no RSU vest events, or a year with large itemized deductions, your regular tax liability drops, which means the gap between your regular tax and your tentative minimum tax is smaller. A smaller gap means less incremental AMT from the ISO exercise.

Common low-income windows for Bay Area tech workers:

• The year you leave a job and your next W-2 starts partway through
• A year you take unpaid leave or a sabbatical
• A year when your RSU vesting cliff has not hit yet
• A year with large charitable deductions that reduce regular income (though note that charitable deductions do not reduce AMTI directly)

Strategy 2: Early Exercise Plus Section 83(b) Election

For startup employees with ISOs at an early-stage company, exercising shortly after grant when the 409A valuation is at or near the strike price eliminates the AMT preference item because the spread is zero or close to zero. The Section 83(b) election (filed within 30 days of exercise) locks in that low FMV as your federal and California tax basis.

This strategy works best when:

• The company has a recent 409A valuation near the strike price (ideally within the last 12 months)
• You have reasonable confidence the company will survive and grow
• The total exercise cost is manageable relative to your cash position
• You have at least 12 months before a likely liquidity event, since you need to hold for one year from exercise to get long-term capital gain treatment on sale

The 30-day deadline on the Section 83(b) election is absolute and has no exceptions. Miss it, and the election option is gone permanently. We build the election filing into our engagement workflow for early exercise clients.

Strategy 3: Spread ISO Exercises Across December and January

Each calendar year resets your AMT calculation. If you have a large number of ISOs you want to exercise and the total spread would create an unacceptably large AMT hit in a single year, splitting the exercise across year-end can distribute the AMT exposure across two tax years. Exercise a portion in late December and the remainder in early January. The spread from each batch goes into a different tax year's AMTI computation.

This requires advance planning because the December portion must settle before December 31. We model the December-January split routinely for clients with large ISO positions approaching a liquidity event.

Strategy 4: Disqualifying Dispositions as a Pressure Valve

If you exercised ISOs in a prior year and paid AMT, you may be able to reduce your AMT credit carryforward recovery timeline by triggering a disqualifying disposition. Selling ISO shares within two years of grant or within one year of exercise converts what would have been long-term capital gain into ordinary income, which eliminates the AMT preference item retroactively for that exercise. The trade-off: you lose the preferential capital gain treatment. We model both paths and present the after-tax numbers before recommending either.

Disqualifying Disposition Math

Strategy 4 above names disqualifying dispositions as a pressure valve. Here is the actual math behind when that trade is worth making.

A disqualifying disposition happens when you sell ISO shares before satisfying both holding-period tests: more than two years from the grant date and more than one year from the exercise date. When you sell early, the ISO's special tax treatment evaporates retroactively. The IRS treats the sale like an NSO exercise-and-sale: the lesser of (a) the actual gain on sale or (b) the spread at exercise becomes ordinary income in the year of sale, and any remaining gain above that is capital gain. Critically, the AMT preference item from the original exercise is reversed. You do not pay AMT twice on the same spread once it has been recharacterized as ordinary income.

The trade-off is easy to state and harder to decide in the moment: you give up long-term capital gain treatment (federal rates up to 20%, plus the 3.8% net investment income tax) in exchange for eliminating an AMT bill that may otherwise sit uncollected as an illiquid credit for years. The math favors a disqualifying disposition when:

• The stock is thinly traded or there is no confidence in a near-term liquidity event, so the long-term capital gain benefit you are protecting may never be realized in practice
• Your marginal ordinary rate is not dramatically higher than your long-term capital gains rate, which is common for filers already near the top marginal brackets, where the rate spread narrows
• The AMT liability the disqualifying sale eliminates is large relative to the incremental ordinary-versus-capital-gain tax cost
• You need the cash from the sale to fund the AMT bill on other shares you are keeping, effectively self-funding the tax on the position you want to hold

The math tips the other way when the company is pre-IPO with a credible path to a liquidity event inside the one-year holding window, since the long-term capital gain treatment you would give up compounds meaningfully on a large paper gain. One more factor to model before recommending an early sale: if the shares would otherwise qualify for the qualified small business stock exclusion, a sale before the five-year QSBS holding period is met forfeits that exclusion entirely, and it also forfeits the AMT-preference exclusion for QSBS gain under IRC Section 1202(a)(4), which treats excluded QSBS gain as excluded for AMT purposes too. We check QSBS eligibility before recommending any early disposition, since a disqualifying disposition and a QSBS exit are two different exits with two different clocks.

Multi-Year ISO Exercise Strategy

Most Bay Area tech employees do not face a single ISO exercise decision. They have a multi-year vesting schedule and a grant of tens of thousands of shares vesting over four years. The planning question is not exercise or don't, it is how to sequence exercises across years so that no single year's AMT preference item pushes AMTI into the steep phase-out zone or generates more AMT credit than can realistically be absorbed.

The building block is what practitioners call the AMT-free zone: the number of shares you can exercise in a given year, given your other income, without your tentative minimum tax exceeding your regular tax. Below that number, the exercise is effectively AMT-free. Above it, every additional share exercised adds close to 26 to 28 cents of AMT for each dollar of spread. The AMT-free zone shifts every year based on your W-2 income, RSU vesting, bonus timing, and the current exemption and phase-out figures in the table above.

A basic multi-year sequencing approach for a large ISO grant:

1. Project the AMT-free zone for the current year and the following two to three years based on known income (W-2, RSU vest schedule, expected bonus).
2. Exercise up to that zone each year, carrying the remaining unexercised vested shares forward.
3. Re-run the projection every year as actual income, 409A valuations, and tax law figures change.
4. Accelerate exercises in any unusually low-income year, such as a sabbatical, a job transition, or a year with large itemized losses.
5. Reserve the final tranche of exercises for the months immediately before an anticipated liquidity event, since the calculus changes once IPO or acquisition timing becomes visible.

Composite example: a senior engineer at a pre-IPO Bay Area company exercising $500,000 of ISOs six months before the S-1 filing. Priya, 38, is a senior engineer at a pre-IPO company (composite profile, not an actual client engagement). She holds 60,000 vested ISOs with a strike price of $3. The company has filed confidentially and expects to go public within six to nine months. The most recent 409A puts fair market value at $11.33, putting the total spread at roughly $500,000 if she exercises everything at once. Her W-2 income is $310,000; her spouse does not work.

Exercising the full $500,000 spread in one year would push AMTI well past the 2026 phase-out completion point for married filing jointly, generating an estimated $130,000 to $145,000 of AMT in a single tax year, due the April after exercise, months before any lockup-expiration liquidity. Instead, we modeled a split: exercise 25,000 shares (spread approximately $208,000) in the current year, and the remaining 35,000 shares (spread approximately $292,000) in January of the following year, assuming the company's expected IPO timeline holds and the 409A does not move materially in the interim. Splitting across the December-January boundary keeps each year's incremental AMT closer to $50,000 to $60,000 instead of concentrating the full hit in one filing season, and it gives her two separate estimated-payment cycles to plan around rather than one.

The trade-off she accepted: exercising in two tranches means two separate one-year clocks for long-term capital gain treatment, one per tranche, and the second tranche's basis depends on a 409A that could still move before exercise. We re-ran the projection quarterly as the IPO timeline firmed up.

The AMT Credit Carryforward: Getting Your Money Back

The AMT credit (Form 8801, Minimum Tax Credit) is one of the most misunderstood concepts in the ISO planning space. Here is the core mechanic.

When you pay AMT due to a timing difference like an ISO exercise, the IRS effectively recognizes that you have prepaid tax on income that will eventually be taxed again at regular rates when you sell the stock. To prevent permanent double taxation, you accumulate an AMT credit equal to the AMT attributable to timing differences. In future years when your regular tax liability exceeds your tentative minimum tax, the AMT credit offsets your regular tax dollar for dollar.

Example: In 2025 you pay $25,000 of AMT on ISO exercises. That $25,000 becomes an AMT credit on Form 8801. In 2026, your regular tax is $80,000 and your tentative minimum tax is $55,000. The $25,000 excess of regular tax over AMT can absorb $25,000 of your credit, reducing your 2026 regular tax bill by $25,000.

The credit fully recovers over time if:

1. Your regular tax consistently exceeds your tentative minimum tax in future years
2. You do not generate large additional AMT preferences in those years that keep your tentative minimum tax elevated

The credit recovery can stall if you continue exercising ISOs in subsequent years, keeping your tentative minimum tax high. We model the credit absorption forecast across a rolling 5-year window for clients with large AMT credit carryforwards.

How the AMT Credit Gets Stuck

Form 8801 is where the AMT credit lives, and it is also where the credit quietly stalls for a large share of taxpayers who exercised ISOs. The mechanics explain why.

Each year, Form 8801 compares your regular tax to your tentative minimum tax for that year. If regular tax exceeds tentative minimum tax, the excess, up to your available credit balance, is allowed as a credit against your regular tax, and your credit balance goes down by that amount. If your tentative minimum tax equals or exceeds your regular tax in a given year, whether because you are back in AMT for a new reason or because your income profile keeps producing a high tentative minimum tax, you absorb none of the credit that year, and the balance simply carries forward, unindexed for inflation, until a year with room to use it.

The credit gets stuck in a few recurring patterns we see in Bay Area engagements:

• Repeat ISO exercises. Exercising a new batch of ISOs every year can generate a new AMT preference every year, keeping tentative minimum tax elevated and leaving no room for the prior year's credit to absorb.
• Large RSU income holding down the regular-versus-AMT gap. RSU income is taxed the same under both systems, so it does not by itself widen the gap between regular tax and tentative minimum tax the way it might seem to.
• A liquidity event that never happens. The credit was designed around the assumption that you eventually sell the shares and pay regular tax on the gain, closing the loop. If the company never goes public and the shares stay illiquid, or you never sell, the credit can sit unused indefinitely. It does not expire, but "does not expire" is not the same as "useful" absent a near-term year with a large regular-tax gap.
• Filing status or income changes that reset the picture. A divorce, a job change to a lower-comp role, or a move to a state with different withholding can each change the annual regular-versus-AMT gap in ways that are easy to miss without an annual Form 8801 projection.

The absorption timeline below shows a representative five-year path for a client who paid $29,000 of AMT on an ISO exercise, then sold the shares in year three, closing the loop and finishing the credit recovery.

Year (post-exercise)	Regular tax	Tentative minimum tax	Credit absorbed	Credit balance remaining
Year 1 (exercise year)	$47,000	$76,000	$0 (AMT paid, not yet absorbed)	$29,000
Year 2	$52,000	$58,000	$0	$29,000
Year 3 (shares sold)	$118,000	$70,000	$25,000	$4,000
Year 4	$90,000	$65,000	$4,000	$0 (fully absorbed)
Year 5	$95,000	$68,000	$0 (no balance left)	$0

Notice years 1 and 2: tentative minimum tax exceeds regular tax in both years, so nothing absorbs even though the client paid no additional AMT in those years. The credit only starts moving in year 3, when the stock sale pushes regular tax above tentative minimum tax. Without the sale, this client's credit could easily have carried at $29,000 for another three or four years. We run this exact forecast for every client with an AMT credit balance, so the recovery timeline is a plan, not a guess.

When the Company Goes Public: AMT Planning Around IPOs and Tender Offers

The most consequential AMT planning situation in the Bay Area is the pre-IPO exercise decision. As a company approaches an IPO, the 409A valuation rises sharply. The window between the last pre-IPO 409A and the actual IPO price is often where the largest AMT exposures originate.

Pre-IPO exercise decisions involve several competing factors:

• AMT exposure at current 409A. How much AMT would you owe if you exercised now versus at IPO price?
• Lockup period. After IPO, most employees are locked up for 180 days. You cannot sell to pay the AMT bill until lockup expires, but the AMT is due April 15 of the year following exercise.
• Qualified small business stock (QSBS). Shares acquired by exercising ISOs in a C corporation that meets the Section 1202 criteria may qualify for the QSBS exclusion, which can exclude up to $10 million of gain from federal tax. Early exercise before the company is too large to qualify is time-sensitive.
• Company-sponsored tender offers. Some pre-IPO companies offer secondary liquidity through tender offers. The tax treatment of tender offer sales depends on whether you meet the ISO holding periods.

We work through the IPO exercise analysis with clients 6 to 12 months before a projected offering. The planning timeline matters because many of the best strategies require action well before the S-1 is filed.

Composite Example: Founder Modeling Exercise Timing on $1 Million of Paper-Value Startup ISOs

Client profile (composite, anonymized). Marcus, 41, is a co-founder and early employee at a Bay Area startup that has not yet raised a round with outside pricing pressure. He holds ISOs currently valued, per the last internal 409A, at just over $1 million in paper spread against his exercise cost. There is no tender offer scheduled and no IPO timeline. His W-2 income is $195,000.

Because there is no near-term liquidity event, the planning question is different from the exercise-before-IPO decision above. It is not "how do I split a known exercise before a known IPO," it is "should I exercise at all before there is any path to cash, and if so, how much." We modeled three paths. Path one: exercise nothing, preserving cash but risking a much larger AMT bill later if the 409A keeps climbing before any liquidity. Path two: exercise the full position now, generating an estimated AMT bill in the $180,000 to $210,000 range on a position with no way to raise cash to pay it, which we ruled out immediately as a solvency problem, not a tax problem. Path three: exercise in tranches sized to the AMT-free zone each year, using his actual W-2 income and the current exemption figures, spending three to four years working through the full grant and revisiting the plan annually as the company's valuation and funding trajectory become clearer.

Marcus chose path three. The plan does not eliminate the eventual AMT cost of exercising a $1 million spread. It sequences that cost across years where he can actually fund it, and it keeps the door open to a disqualifying disposition on any tranche if the company's prospects change before he can sell. We revisit the projection every year, not just once at grant.

Worked Example: Managing AMT Across Two Tax Years

Client profile (composite, anonymized). David, 34, senior engineer at a San Jose-based SaaS company that recently closed a Series D at a $600 million valuation. He has 50,000 vested ISOs with a strike price of $0.80. The current 409A valuation is $7.40. The company is targeting an IPO in 18 to 24 months. David's W-2 income is $280,000. Married, filing jointly. Spouse income $85,000.

The AMT exposure if he exercises all 50,000 ISOs in one year:

• ISO spread: 50,000 x ($7.40 - $0.80) = $330,000
• Total AMTI (roughly): $365,000 + $330,000 = $695,000, minus reduced exemption
• Estimated AMT: approximately $91,000
• Less estimated regular tax: approximately $86,000
• Incremental AMT owed: approximately $5,000 (because regular tax is close to AMT in this income range)

Wait, that sounds small. The reason is that David's high W-2 income means his regular tax is already high, so the gap between regular tax and tentative minimum tax is modest. This is actually a good year to exercise a large block because the incremental AMT cost is low. We ran the projection, confirmed the $5,000 incremental AMT, and David exercised 40,000 ISOs in November, keeping the remaining 10,000 for January to manage cash flow. He filed a Section 83(b) election for the unvested portion of the early exercise tranche.

Result: David now holds 40,000 ISO shares with a cost basis of $0.80, a California basis of $7.40, and a one-year holding clock running. At IPO, if the stock is at $22, his federal long-term capital gain is $22 - $0.80 = $21.20 per share on 40,000 shares = $848,000, taxed at 20% federal rate = $169,600. His AMT credit carryforward from the $5,000 AMT paid will offset future regular tax. Had he waited and exercised at $22 IPO price, the ISO spread alone would have been $21.20 x 40,000 = $848,000 in AMT preferences, generating a federal AMT bill of roughly $220,000 on phantom income before any liquidity.

What Documents You Need for AMT Planning

An accurate AMT projection requires:

• Form 3921 for each prior-year ISO exercise (issued by your company, shows exercise date, shares, strike price, FMV at exercise)
• Current option grant agreement showing grant date, strike price, total shares, and vesting schedule
• Most recent 409A valuation report for private company stock
• Prior-year Form 8801 showing your AMT credit carryforward if you have paid AMT in prior years
• Current-year income projection including W-2, any RSU vest schedule, bonus expectations, and any other income sources
• Section 83(b) election copies if you filed any in prior years
• California Form 3510 (prior-year credit for prior-year AMT, if applicable)

IRS Forms Reference: 6251, 8801, and 3921

Form	Purpose	Who files	Timing
Form 6251	Computes the Alternative Minimum Tax and attaches the calculation to your return	Taxpayer, attached to Form 1040	Filed with your return for any year the AMT computation produces a liability, or when required to determine whether it applies
Form 8801	Claims the Credit for Prior Year Minimum Tax; tracks and applies the AMT credit carryforward	Taxpayer	Filed every year after you have paid AMT from a timing preference like an ISO exercise, until the credit is fully used
Form 3921	Reports the exercise of an incentive stock option, including grant date, exercise date, shares, exercise price, and fair market value at exercise	Your employer issues it to you and files a copy with the IRS	Issued by January 31 of the year following the calendar year of exercise

Form 3921 is the source document. Without it, reconstructing the AMT preference amount for a prior-year exercise means digging up option grant agreements and payroll records. Form 6251 is where that preference item shows up on your return in the exercise year. Form 8801 is where the resulting credit lives every year afterward until it is used up. We ask new clients for at least the last three years of these three forms before building an AMT projection.

AMT and the Intersection With Other Bay Area Tax Issues

AMT does not exist in isolation. It interacts with several other planning areas that are common for Bay Area tech workers.

QSBS (Section 1202). The QSBS gain exclusion applies to federal regular tax. AMT has its own treatment: QSBS gains excluded under Section 1202 are excluded for AMT purposes as well (under the 2018 Tax Cuts and Jobs Act changes), which is a significant improvement over prior law. But the interplay between the exclusion percentage and the AMT calculation is still worth modeling.

Net investment income tax. The 3.8% net investment income tax (NIIT) under IRC Section 1411 is separate from AMT. If you sell ISO shares and recognize long-term capital gain after meeting the holding period requirements, that gain may be subject to NIIT if your modified AGI exceeds $250,000 (married filing jointly). AMT does not shield you from NIIT.

Estimated tax payments. AMT liability from ISO exercises is not typically subject to employer withholding. You are responsible for making estimated tax payments to avoid underpayment penalties. The safe harbor under IRC Section 6654 is to pay either 100% of the prior-year tax liability (110% if prior-year AGI exceeded $150,000) or 90% of the current-year liability. In a large ISO exercise year, the prior-year safe harbor is often the better choice.

State withholding on ISO exercises. California requires withholding on the ISO spread when you exercise. Your employer should report the spread as supplemental wages on your W-2. If they do not withhold correctly, you may owe California estimated taxes as well.

Service Coverage for AMT Planning Clients

Silicon Valley Tax provides the following services for clients with AMT planning needs:

• Pre-exercise AMT projection modeling comparing regular tax versus tentative minimum tax at various exercise quantities
• December-January exercise timing analysis for spreading ISO exercises across tax years
• Early exercise and Section 83(b) election filing for pre-IPO startup employees
• AMT credit carryforward (Form 8801) tracking and absorption forecasting
• California basis reconciliation for ISO shares with federal-California basis differences
• Disqualifying disposition analysis for clients who need to generate ordinary income to retire AMT credit faster
• Pre-IPO exercise strategy development coordinated with the company's equity plan administrator
• QSBS qualification analysis for ISO shares in qualifying C corporations under IRC Section 1202
• Estimated tax payment scheduling to avoid underpayment penalties in ISO exercise years
• Federal and California tax return preparation with full AMT schedule, Form 6251, and Form 8801

Our Office and How to Engage

Silicon Valley Tax is located at 2051 Junction Ave Suite 200, San Jose CA 95131. We serve clients throughout the South Bay, Peninsula, and East Bay, and we handle fully virtual engagements for clients who prefer to work remotely.

For AMT planning, we strongly recommend a planning conversation before you exercise, not after. The AMT bill is locked in when the exercise happens. Post-exercise planning is limited to managing cash flow and the carryforward. Pre-exercise planning is where the real leverage is. Call (408) 383-9870 or use the online booking form to schedule a complimentary 30-minute consultation.

Frequently Asked Questions About AMT Tax Planning

How does exercising ISOs trigger AMT?

When you exercise incentive stock options, the spread between your strike price and the current fair market value is added to your alternative minimum taxable income (AMTI) as a preference item under IRC Section 56(b)(3). If your total AMTI exceeds the AMT exemption amount, you owe AMT at 26% or 28% on the excess. This can result in a significant tax bill on income you have not yet received as cash because you have not sold the shares. The AMT applies in the year of exercise, not the year of sale.

What is the AMT credit carryforward and how do I use it?

The AMT credit (Form 8801) is generated when you pay AMT due to timing differences like ISO exercises. In future years when your regular tax liability exceeds your tentative minimum tax, the credit offsets your regular tax liability dollar for dollar. The credit represents a prepayment of future regular tax and can be recovered over time. We model the credit absorption timeline as part of every ISO exercise analysis.

Can I do an early exercise to avoid AMT on my ISOs?

Yes. If you exercise ISOs when the 409A valuation is at or near your strike price, the AMT preference item is minimal because the spread is small. Filing a Section 83(b) election within 30 days of exercise locks in that low FMV as your tax basis. If the company grows, shares appreciate while your AMT exposure stays tied to the low FMV at exercise. We evaluate the downside risk against the AMT upside before recommending early exercise for any client.

Does California have its own AMT?

California still imposes an active individual AMT (Schedule P on Form 540) at a 7% rate above an exemption threshold. Layered on top of that, California does not conform to federal ISO treatment: California taxes the ISO spread as ordinary income at exercise (up to 13.3%), like an NSO. Both the California AMT projection and the California regular-tax bill on the ISO exercise need to be modeled together. The California ordinary-income tax generates a compensating basis step-up used when you sell the shares.

What documents do I need for AMT tax planning around ISO exercises?

Gather: Form 3921 for each ISO exercise, your option grant agreement, the most recent 409A valuation, your prior-year tax return showing any AMT credit carryforward on Form 8801, your current-year income projections including W-2 and RSU vest schedule, and any Section 83(b) elections filed. We use all of this to build a projection of your regular tax and tentative minimum tax before any additional exercises.

Related Resources

For additional context on equity compensation tax, see our pages on equity compensation tax overview, ISO vs NSO comparison, Section 83(b) election mechanics, and post-IPO tax strategy. For Bay Area city-specific coverage, see our pages for San Jose tax accountant, Palo Alto tax accountant, and Mountain View tax accountant.

Related reading: AMT planning strategies for 2026, cashless ISO exercises and AMT: how to avoid a surprise tax bill.