Alternative Minimum Tax Planning: When AMT Still Hits, How to See It Coming, and ISO Exercise Timing
Post-TCJA AMT — Narrower, But Still Real
The alternative minimum tax was originally enacted in 1969 to make sure that high-income taxpayers using a long list of preferences and deductions could not zero out their federal tax bill. The mechanics are a parallel tax system: compute regular tax under the normal rules, compute AMT under a separate set of rules with fewer deductions and a flatter rate structure, pay the higher of the two. For decades the AMT crept down the income ladder because the exemption was not indexed for inflation, and by the mid-2000s millions of upper-middle-class households were paying it every year.
The Tax Cuts and Jobs Act of 2017 changed the math substantially. For tax years 2018 through 2034, the TCJA raised the AMT exemption from roughly $54,300 to $70,300 for single filers (and from $84,500 to $109,400 for married filing jointly), then continued indexing those figures for inflation. The phase-out threshold (the income level above which the exemption starts to disappear) was pushed up even more dramatically, from $120,700 single and $160,900 MFJ to $500,000 and $1,000,000 respectively. The TCJA also capped the SALT deduction at $40,000, which removed the largest single AMT preference for high-tax-state residents.
The combined effect was to take roughly 96% of the households who were paying AMT in 2017 out of the AMT system by 2018. The Joint Committee on Taxation estimated that about 5 million households paid AMT in 2017; that number dropped to under 200,000 in 2018 and has stayed there since. Alternative minimum tax planning went from a routine part of any high-income return to a targeted exercise.
The people who still pay AMT today fall into a few categories. ISO exercises produce the largest AMT bills we see in practice, because the bargain element on an ISO exercise is included in AMT income but not in regular taxable income. Private activity bond interest (tax-exempt for regular tax, taxable for AMT) catches investors with large municipal bond portfolios in certain bonds. Depreciation timing differences (regular tax uses MACRS, AMT uses ADS or 150% declining balance) catch real estate investors and equipment-heavy businesses. And a handful of large itemized deduction patterns can still produce AMT, especially when state taxes paid in a single year happen to spike above what the exemption absorbs.
Alternative minimum tax planning today is mainly about three things: identifying the specific transactions that trigger AMT (so they can be timed across years), tracking the dual basis for assets with regular-vs-AMT differences (so the future regular tax matches the future AMT correctly), and managing the minimum tax credit under Section 53 (so AMT paid in one year is recovered in a later year when regular tax exceeds AMT).
2026 Exemption Amounts and Phase-Outs
For the 2026 tax year, the AMT exemption amounts under IRC §55(d) and the inflation adjustments in Rev. Proc. 2025-32 are $88,100 for single and head of household filers, $137,000 for married filing jointly and surviving spouses, and $68,500 for married filing separately. The exemption begins to phase out at $626,350 for single and head of household, at $1,252,700 for married filing jointly, and at $626,350 for married filing separately. The phase-out is at 25 cents per dollar of AMTI above the threshold, so the exemption disappears completely at about $978,750 for single filers and $1,800,700 for MFJ.
The AMT rates themselves are flat compared to the regular tax brackets. The first $239,100 of AMTI above the exemption (for 2026, MFJ and single) is taxed at 26%. AMTI above that breakpoint is taxed at 28%. Long-term capital gains and qualified dividends keep their preferential rates inside the AMT calculation, which is why pure capital gains income rarely creates AMT on its own.
These exemption numbers are scheduled to drop at 2034 (extended by the One Big Beautiful Bill Act from the original 2025 sunset) Before the OBBBA extension (which extended TCJA through 2034), if TCJA had expired on schedule. Without an extension, the 2026 AMT exemption would revert to pre-TCJA inflation-adjusted levels (roughly $86,200 single and $134,000 MFJ in pre-TCJA terms, but adjusted upward for inflation through 2034 (extended by the One Big Beautiful Bill Act) the actual reversion figures land near the current TCJA numbers, with much lower phase-out thresholds around $164,100 single and $218,800 MFJ). The phase-out floor is the bigger problem at sunset: phase-outs starting at $164K single income would drag many more high earners into AMT exposure. Alternative minimum tax planning will need to revisit the math after Congress acts (or fails to act) on the sunset.
For now (and for the 2026 tax return filed in early 2027), the high exemption and high phase-out floor mean that most W-2 households below $500,000 of AGI do not encounter AMT at all. The exposure starts at higher income levels, and almost always in connection with a specific preference item like an ISO exercise, a depreciation difference, or a large private activity bond holding.
What Still Triggers AMT in 2026
The current short list of AMT triggers, in rough order of how often we see them in practice:
ISO exercises. The bargain element on an exercise of an incentive stock option (the difference between fair market value at exercise and the strike price) is excluded from regular tax in the year of exercise (assuming the stock is held long enough to be a qualifying disposition), but it is fully included in alternative minimum taxable income under IRC §56(b)(3). A founder or early employee who exercises a large ISO grant at a high 409A valuation can owe six or seven figures of AMT in the year of exercise, on paper gain only, with no proceeds from selling the stock. This is the single most common AMT bill we work on at the firm.
Private activity bond interest. Interest on certain tax-exempt municipal bonds issued to finance private projects (airports, stadiums, certain housing) is exempt from regular federal tax but included in AMT income under IRC §57(a)(5). Investors who do not screen their muni portfolios for PAB content can carry unexpected AMT exposure inside what looks like fully tax-exempt income. Many muni funds disclose the PAB portion on the annual tax statement; the line is worth checking each January.
Depreciation timing differences. The regular tax system uses MACRS depreciation, with 200% declining balance for most personal property. The AMT system requires 150% declining balance, or in some cases the ADS straight-line method. The difference between MACRS and AMT depreciation is a preference item under IRC §56(a)(1). The difference reverses over the life of the asset, so it is purely a timing item, but the year-by-year mismatch can push a real estate investor into AMT in years when accelerated depreciation runs hot.
State and local tax deductions. Before the TCJA cap, SALT was the biggest AMT preference for high-income taxpayers in New York, California, and New Jersey. The $40,000 cap reduced the size of this preference dramatically, and most high earners now hit the SALT cap on the regular tax side, leaving little or no SALT to add back for AMT. This is the main reason that high-tax-state professionals are mostly out of AMT now. The cap is itself were extended through 2034 by the One Big Beautiful Bill Act; if it expires, SALT becomes a major AMT trigger again.
Miscellaneous itemized deductions. Pre-TCJA, unreimbursed employee business expenses and investment expenses were AMT preference items. The TCJA eliminated these deductions for regular tax purposes through 2034 (extended by the One Big Beautiful Bill Act), so they no longer appear on either calculation. If they return after sunset, alternative minimum tax planning has to consider them again.
Investment interest expense. Investment interest is deductible against investment income for both regular tax and AMT, but the definition of investment income differs slightly between the two systems. Taxpayers with large margin loans funding portfolios can occasionally see an AMT adjustment from this difference.
Net operating loss carryovers. The AMT NOL is calculated separately and can produce a different deduction than the regular tax NOL. For taxpayers with large business losses, the two NOLs need to be tracked in parallel.
ISO Exercise — The Spread, the Dual Basis, and How to Time It
Incentive stock options are the central case for alternative minimum tax planning at private companies. The mechanics are not complicated, but the timing decisions can move six figures of tax.
When an employee exercises an ISO and holds the stock (does not immediately sell), the bargain element (fair market value at exercise minus strike price) is excluded from regular taxable income, by design. Section 422 of the Code is what makes ISOs ISOs: assuming the holding period requirements are met (more than two years from grant and more than one year from exercise), the entire gain at sale is long-term capital gain, with no compensation income recognized along the way.
AMT does not respect this preference. Under IRC §56(b)(3), the bargain element is added to AMTI in the year of exercise. If the employee exercises 100,000 ISOs at a strike of $1 when the 409A valuation is $20, the regular tax shows no income, but AMTI includes $1,900,000 of bargain element. After exemption and phase-out, the AMT bill on that exercise can easily exceed $500,000.
The dual basis problem follows from this. For regular tax, the basis of the stock acquired by ISO exercise is the strike price ($1 per share in the example). For AMT, the basis is the strike price plus the bargain element already taxed under AMT ($20 per share). When the stock is later sold, the regular tax gain and the AMT gain differ by the bargain element. The eventual sale produces a negative AMT adjustment (because AMT gain is lower than regular gain), which is the mechanism by which the Section 53 credit recovers the AMT paid at exercise. Tracking the dual basis on every ISO lot is essential. Tax preparation software handles this if the prior-year exercise was reported correctly on Form 6251. If it was not, the credit can be lost.
Timing the ISO exercise is the largest piece of use in alternative minimum tax planning. The bargain element is fixed at the moment of exercise, based on the difference between FMV at exercise and strike. By exercising in a year when the spread is small (early, before significant appreciation), the AMT exposure can be kept low or eliminated. The early exercise strategy is most useful in the first 12 to 24 months after grant, when the company’s 409A valuation is still close to the strike price. Once the company has raised a priced round at a much higher valuation, the spread is large and the AMT is unavoidable on any full exercise.
An alternative is to exercise just enough each year to absorb the AMT exemption without pushing into AMT territory. Calculate the AMTI ceiling: regular taxable income, plus the exemption, plus the 26% bracket up to $239,100 of AMTI. As long as the exercise keeps the bargain element below the point where AMT exceeds regular tax, no actual AMT is owed. This requires running Form 6251 projections in real time, ideally before the exercise is committed.
A third path is the qualifying disposition that becomes a disqualifying disposition. If the stock is sold within the same calendar year as the exercise, the ISO is disqualified, the bargain element becomes regular wage income (subject to ordinary rates and FICA), and the AMT preference disappears. For employees who want liquidity and do not want to carry AMT exposure on illiquid shares, a same-year disqualifying disposition often beats holding for the long-term capital gains rate after factoring in the AMT cost of capital and the risk that the shares lose value before a real liquidity event.
The worst-case scenario is the one we see most often: an employee exercises ISOs near the top of a private company’s valuation, owes a large AMT bill on April 15, and the company’s value drops before any liquidity event. The AMT paid was real cash. The dual basis still exists, but recovering the Section 53 credit requires future regular tax that exceeds future AMT, and the lower-valued stock no longer produces enough gain at sale to recover the credit. Alternative minimum tax planning at the exercise stage has to consider downside scenarios, not just the upside math.
The Minimum Tax Credit Under Section 53
IRC §53 provides a credit against future regular tax for AMT paid in prior years that was attributable to timing items (deferral preferences) rather than exclusion items. The credit is the safety valve that makes AMT a timing tax for most preferences, not a permanent additional tax.
The mechanics: in any year that regular tax exceeds tentative minimum tax (TMT), the excess can be offset by the accumulated minimum tax credit from prior years. The credit is carried forward indefinitely (under current law) and does not expire until used. Form 8801 tracks the credit balance from year to year.
Not all AMT becomes a credit. AMT attributable to exclusion items (state tax deductions, personal exemptions, miscellaneous itemized deductions) does not generate a credit. AMT attributable to deferral items (ISO bargain element, depreciation timing, private activity bond interest) does generate a credit. The Form 8801 calculation separates the deferral portion from the exclusion portion of the prior-year AMT.
For ISO exercises, the AMT is almost entirely from a deferral preference (the bargain element), so almost all of the AMT becomes a Section 53 credit. The credit is recovered when the stock is eventually sold. At sale, the regular tax gain is computed using the regular basis (strike price), and the AMT gain is computed using the AMT basis (strike plus bargain element). The difference creates a negative AMT adjustment in the year of sale, which reduces TMT below regular tax, which unlocks the Section 53 credit.
In a clean fact pattern, the timing works out: AMT paid in year 1 (exercise) is fully recovered in year 5 or whenever the stock is sold. In messier patterns, the credit can take years to recover, or never fully recover. If the eventual sale produces less gain than the bargain element (because the stock price dropped), the AMT basis exceeds the sale price and the AMT adjustment is limited. The credit remains on the books and can be used against future years’ regular tax above TMT, but the recovery is gradual and uncertain.
Alternative minimum tax planning for the credit recovery side involves looking at future years of expected income and structuring transactions to create regular-tax-above-TMT years. Roth conversions in retirement, capital gain harvesting, and large bonus years can all create opportunities to absorb the credit faster. Without planning, the credit can sit on Form 8801 unused for a decade.
Multi-Year Planning: Bunching, Exercising in Tranches, and Credit Use
The flat AMT rate structure (26% to $239,100 of AMTI above the exemption, 28% above that) creates a planning opportunity that the regular tax brackets do not. Because AMT is essentially flat, splitting a large preference item across multiple years does not save much on the AMT side. But because the regular tax brackets are graduated, splitting income across years saves regular tax. The combination means that ISO exercises and other AMT-triggering events should be modeled across multiple years, not just within the current year.
Bunching the exercise: if the employee plans to exercise 100,000 ISOs at $20 spread, doing it all in one year produces a large AMT bill (say $500,000) and the Section 53 credit becomes recoverable when the stock sells. Doing it across five years (20,000 per year) keeps each year’s AMT below the exemption phase-out floor and may eliminate AMT entirely in each year, but it also means the bargain element accumulates regular tax basis differences gradually and the company’s 409A may have risen each year, increasing the bargain element on later tranches.
The right answer depends on whether the company’s valuation is going up or down, whether the employee has other income that would absorb AMT credit recovery, and how soon a liquidity event is expected. A general guideline: if the company is rapidly appreciating and a sale is more than five years out, partial exercises in lower-valuation years are usually better. If the company is at peak valuation and a sale is imminent, a single full exercise followed by an early sale is often the cleaner answer.
Credit recovery planning: for taxpayers with accumulated Section 53 credit balances from prior ISO exercises, the planning question shifts to generating regular-tax-above-TMT years. The bigger the gap between regular tax and TMT in a given year, the more credit can be used. Roth IRA and Roth 401(k) conversions are a powerful tool here: the conversion income is ordinary income for both regular tax and AMT, but the AMT adjustments are minimal, so the regular tax tends to exceed TMT by a wide margin. We have used this strategy for clients with seven-figure credit balances from ISO exercises to convert traditional retirement assets to Roth over a series of years, using the credit to offset the regular tax on the conversion.
Capital gain harvesting in years between exercise and sale can also help, but the rates are lower so the regular-tax-above-TMT spread is narrower. The right priority is usually: convert retirement accounts to Roth (highest regular tax rates), then harvest capital gains, then accelerate other ordinary income items if available.
California AMT — A Separate Calculation
California has its own alternative minimum tax that runs in parallel with the federal AMT and follows a different set of rules. California Revenue and Taxation Code Section 17062 imposes a 7% AMT rate on a separately calculated California AMTI, with a $46,989 exemption for single filers and $62,650 for MFJ for 2026 (subject to inflation adjustment and phase-outs starting at $260,000 of AMTI for single and $349,000 for MFJ).
The California AMT calculation starts with federal AMTI and adjusts for California-federal differences. The state does not allow the federal AMT exemption (it uses its own), and several preference items are calculated differently. ISO bargain element is an AMT preference for California just as for federal, so California AMT triggers on ISO exercises in the same way.
California does not conform to many federal tax provisions, so the California regular tax and the California AMT both look different from their federal counterparts. The combination can produce a California AMT bill in a year when there is no federal AMT, or vice versa. For a high-income California resident exercising ISOs, the planning has to model federal AMT, federal regular tax, California AMT, and California regular tax simultaneously.
California also has its own AMT credit under Revenue and Taxation Code Section 17063. The credit is carried forward indefinitely and recovered in future years when California regular tax exceeds California TMT. The recovery mechanics work like the federal Section 53 credit, but with the California exemption amounts and rate structure.
Alternative minimum tax planning for California residents exercising ISOs has to factor in both layers. A California resident exercising $1M of ISO bargain element will typically face roughly $260,000 of federal AMT and roughly $65,000 of California AMT, both of which become credits for future recovery. The combined AMT bill of $325,000 has to be funded with current cash, even though the stock is illiquid. Founders and early employees facing this combined exposure sometimes look at residency relocation before exercise, but the timing rules under California’s source-of-income statutes mean a pre-exercise move only helps if the move is genuine and well in advance of the exercise.
Form 6251 Walkthrough
Form 6251 (Alternative Minimum Tax — Individuals) is where the federal AMT calculation lives on the return. The form has three parts and the structure tracks the conceptual mechanics of the tax.
Part I — Alternative Minimum Taxable Income. The starting point is taxable income from Form 1040 (line 15). Adjustments and preferences are added: state and local tax deductions claimed on Schedule A (line 2a), tax refunds included in regular income (line 2b through 2c), investment interest expense differences (line 2d), depletion (line 2e), net operating loss differences (line 2f), private activity bond interest from Form 1099-INT box 9 (line 2g), depreciation timing differences (line 2k through 2t), and a host of less common items. The ISO bargain element is reported on line 2i: this is the line that creates the AMT bill for ISO exercises. The total of regular taxable income plus all positive adjustments minus negative adjustments produces AMTI on line 4.
Part II — Alternative Minimum Tax. The exemption is applied (line 5), with the phase-out reducing the exemption above the threshold. The result on line 6 is AMTI after exemption. Lines 7 through 9 apply the 26% and 28% rates (with the breakpoint at $239,100 of AMTI for 2026). Long-term capital gains and qualified dividends get their preferential rates inside the AMT calculation via the Qualified Dividends and Capital Gain Tax Worksheet. The result is tentative minimum tax. Subtracting regular tax (line 9 against line 10) gives the AMT, which is reported on Schedule 2 (line 1) and added to the Form 1040 tax.
Part III — Tax Computation Using Maximum Capital Gains Rates. This is the alternative computation that applies when the taxpayer has significant long-term capital gains or qualified dividends. It preserves the preferential rates inside the AMT system.
Most tax software handles the Form 6251 calculation automatically once the inputs are in place. The important inputs that require manual attention are the ISO bargain element (which has to be reported on Form 3921 by the employer and then entered on Form 6251 line 2i), the depreciation differences (which require parallel AMT depreciation schedules), and the private activity bond interest (which is reported separately on Form 1099-INT). Missing any of these inputs produces an understated AMT and an audit risk if the IRS receives the Form 3921 separately and reconciles it.
Form 8801 (Credit for Prior Year Minimum Tax) handles the Section 53 credit on the recovery side. The form calculates the portion of prior-year AMT attributable to deferral items versus exclusion items, tracks the carryforward balance, and applies the credit against current-year regular tax above TMT. Form 8801 is one of the most commonly missed forms on self-prepared returns; if there is a prior-year AMT balance and no current-year Form 8801, the credit is being left on the table.
Frequently Asked Questions
Does alternative minimum tax planning still matter after the Tax Cuts and Jobs Act?
Yes, but for a much narrower group of taxpayers than before. The Tax Cuts and Jobs Act raised the AMT exemption and pushed the phase-out threshold dramatically higher for tax years 2018 through 2034, with the result that roughly 96% of households who used to pay AMT no longer do. For most W-2 professionals in the $200,000 to $500,000 income range, especially those without large preference items, alternative minimum tax planning is no longer a routine concern. The regular tax bill is the bill.
But AMT did not go away. It still hits a specific group of taxpayers hard: employees exercising incentive stock options at private companies (the bargain element is the largest AMT preference left in the Code), investors with significant holdings of private activity bonds in their municipal portfolios, real estate investors and equipment-heavy business owners with large depreciation timing differences, and a smaller number of taxpayers whose facts happen to land in the narrow band where regular tax falls short of AMT.
For those groups, alternative minimum tax planning is more important than ever, because the AMT exposure now comes in concentrated, lumpy events rather than smooth annual creep. An ISO exercise that produces $1 million of bargain element will generate $260,000 or more of federal AMT in a single year, with no offsetting cash from the stock sale. A real estate investor placing several million dollars of cost-segregated assets in service can see a sharp AMT spike in the depreciation acceleration year. The transactional nature of post-TCJA AMT makes the planning episodic rather than continuous, but it makes the stakes higher when AMT does hit.
There is also a sunset consideration. The TCJA’s AMT-friendly provisions are were extended through 2034 by the One Big Beautiful Bill Act unless Congress extends them. If the expiration happens on schedule, the AMT exemption and phase-out thresholds revert to pre-TCJA inflation-adjusted levels, and millions of upper-middle-class households would be back in AMT exposure starting with tax year 2026. The SALT cap is also scheduled to expire, which would restore the largest pre-TCJA AMT trigger for high-tax-state residents. Alternative minimum tax planning will need to revisit the math after Congress acts (or fails to act) on the sunset, and the planning for 2026 income is harder to finalize until the legislative outcome is clearer.
For taxpayers who are not in the affected groups today, alternative minimum tax planning is mostly a year-end check rather than an active strategy. Run Form 6251 each year (or have your preparer run it) to confirm there is no AMT exposure. If there is, work backward from the trigger to see what can be timed differently. For taxpayers who hold ISOs at private companies, who own large municipal bond portfolios, or who are placing depreciable assets in service, alternative minimum tax planning is a year-round exercise that should drive timing decisions on exercises, asset purchases, and portfolio composition.
The Reed Corporation runs AMT projections as part of every high-income tax return and every multi-year planning engagement. When the projection shows AMT exposure, the conversation with the client happens before the year closes, not during the next April filing rush.
How should alternative minimum tax planning work around an ISO exercise at a private company?
The single most important rule of alternative minimum tax planning for ISO exercises: the AMT exposure is locked in at the moment of exercise, based on the difference between fair market value at exercise and the strike price. The choice to exercise (and how much to exercise) is where all the use is. After the exercise is done, the AMT is what it is, and the only remaining variables are when to sell the stock and how to recover the Section 53 credit.
Step one is calculating the bargain element. The fair market value at exercise is typically the most recent 409A valuation if the company is private, or the closing price on the exercise date if the company is public. The strike price is set at grant. The number of shares exercised times the per-share spread is the bargain element. For a private company with a high 409A and a low strike (a common founder or early employee profile), the per-share spread can be $10, $30, $100 or more.
Step two is modeling the AMT bill. Run Form 6251 with the bargain element added on line 2i. Apply the exemption ($88,100 single, $137,000 MFJ for 2026), subtract regular taxable income, apply the 26%/28% rates to the AMTI in excess of exemption. The output is the AMT for the year. For a single filer with $200,000 of W-2 income exercising 50,000 ISOs at a $20 spread (so $1,000,000 of bargain element), the AMT bill lands around $260,000 to $280,000 depending on other items. That tax is due April 15 of the following year regardless of whether the stock has been sold or has any market.
Step three is choosing how much to exercise. Alternative minimum tax planning for ISOs typically involves comparing three paths: full exercise (largest AMT bill, fastest path to long-term capital gains treatment on the eventual sale), partial exercise (smaller annual AMT, exposure spread across multiple years, more flexibility if the company’s valuation changes), and same-year disqualifying disposition (exercise and sell within the calendar year, which converts the bargain element to wage income and eliminates the AMT preference but loses long-term capital gains treatment).
The exemption-utilization strategy is often the cleanest approach for mid-sized exercises. Calculate the AMTI ceiling that produces zero AMT (regular taxable income plus the AMT exemption plus the headroom below the regular tax equivalence point). Exercise only the number of shares whose bargain element fits within that ceiling. The result is a partial exercise that triggers no AMT in the current year. Repeat in subsequent years, ideally before the company’s 409A valuation rises further.
Step four is funding the AMT. The AMT bill on an ISO exercise has to be paid in cash with no proceeds from the exercise itself (because the shares are not being sold). For private company exercises this means the employee is fronting the tax from outside resources. We have worked with clients who have funded large AMT bills through margin loans against other portfolio holdings, sales of liquid assets, and structured settlements with the company for cash bonuses tied to the exercise. The funding question has to be answered before the exercise is committed, not after the April 15 letter from the IRS arrives.
Step five is tracking the dual basis. The regular tax basis of the ISO stock is the strike price. The AMT basis is the strike plus the bargain element. The two numbers have to be carried separately for as long as the stock is held. When the stock is eventually sold (in a qualifying disposition, more than two years from grant and more than one year from exercise), the regular tax gain and the AMT gain differ by the bargain element. The difference generates a negative AMT adjustment in the year of sale, which unlocks the Section 53 credit from the year of exercise. Alternative minimum tax planning has to capture the basis tracking in the year of exercise so the recovery works in the year of sale.
Step six is the credit recovery. The Section 53 credit from a large ISO exercise can sit on Form 8801 for years before it is recovered. Speeding up the recovery requires generating future years with regular tax above tentative minimum tax. Roth conversions are the most efficient way to do this for taxpayers with significant traditional retirement accounts. The conversion income is fully taxable at ordinary rates for regular tax, with minimal AMT impact, so the regular-tax-above-TMT spread is wide and the credit can be absorbed quickly. We have used multi-year Roth conversion strategies to recover seven-figure ISO AMT credits in three to five years rather than the decade-plus that would otherwise be required.
How does alternative minimum tax planning change if the TCJA exemption were extended through 2034 by the One Big Beautiful Bill Act?
If the TCJA-era AMT provisions expire on schedule at 2034 (extended by the One Big Beautiful Bill Act from the original 2025 sunset), the alternative minimum tax planning landscape changes substantially for tax years starting in 2026. The exemption amounts and (more ) the phase-out thresholds revert to pre-TCJA levels, indexed for inflation through 2034 (extended by the One Big Beautiful Bill Act). The result would be a much wider AMT footprint, pulling in households at lower income levels than the current rules cover.
The current law (TCJA through 2034 (extended by the One Big Beautiful Bill Act)) sets the 2026 AMT exemption at $88,100 single and $137,000 MFJ, with phase-outs starting at $626,350 single and $1,252,700 MFJ. Without an extension, the post-sunset 2026 exemption would be lower (closer to $86,000 single and $134,000 MFJ in inflation-adjusted terms), but the more significant change is the phase-out threshold dropping to roughly $164,100 single and $218,800 MFJ. The phase-out floor at $164K is the killer for the upper-middle-class taxpayer base that left AMT in 2018.
The SALT cap is also were extended through 2034 by the One Big Beautiful Bill Act. If it does, taxpayers in New York, California, New Jersey, Connecticut, Massachusetts, and other high-tax states regain the unlimited SALT deduction for regular tax purposes, which historically was the single largest AMT preference. A New York taxpayer with $500,000 of income and $50,000 of state and local taxes had roughly $50,000 of AMT add-back in the pre-TCJA system. The combined effect of the phase-out drop and the SALT cap expiration would put millions of households back into AMT exposure starting in 2026.
Alternative minimum tax planning for the 2026 sunset scenario requires monitoring the legislative situation through 2025 and into early 2026. Several scenarios are plausible: full extension of the TCJA AMT provisions (in which case nothing changes), partial extension (some provisions extended, some allowed to expire), or full sunset (the pre-TCJA rules return). Each scenario produces a different planning posture, and committing to a strategy before Congress acts is risky.
For taxpayers who would be exposed to AMT under the sunset scenario, the most useful pre-2026 planning is accelerating preference items into 2025 (the last year of TCJA rules) where possible. Selling a position with large built-in capital gains in 2025 rather than 2026 may be neutral for AMT (because capital gains keep their preferential rate inside AMT), but accelerating depreciation timing items, recognizing private activity bond gains, and structuring ISO exercises into 2025 rather than 2026 may produce better outcomes if the post-sunset exemption is meaningfully lower.
For taxpayers planning ISO exercises, the calculus is more nuanced. The bargain element is the same preference under either set of rules, but the after-exemption tax depends on the exemption amount. Exercising in 2025 (with a higher exemption and higher phase-out threshold) may produce a smaller AMT bill than exercising the same shares in 2026 if the sunset happens. For employees with vested ISOs and a near-term liquidity event in the company, this is a real consideration for late-2025 planning.
Alternative minimum tax planning for residents of high-tax states should also model the SALT cap expiration carefully. If the cap goes away, state income taxes become an unlimited regular tax deduction again but a full AMT add-back, which can push high-income state residents back into AMT for the first time in eight years. The planning move is to model both scenarios and prepare for either outcome rather than betting on a specific legislative result.
How does alternative minimum tax planning use the Section 53 credit in subsequent years?
The Section 53 credit (formally called the credit for prior year minimum tax) is the recovery mechanism that turns AMT from a permanent tax into a timing tax for deferral preferences. AMT paid on a deferral preference (like an ISO bargain element or a depreciation timing difference) does not stay paid forever; it becomes a credit that offsets future regular tax above the future tentative minimum tax. Alternative minimum tax planning has to manage this credit recovery as actively as it manages the original AMT exposure.
The mechanics on Form 8801 work as follows. Step one is determining how much of the prior-year AMT was attributable to deferral items versus exclusion items. The form recomputes the prior-year AMT using only the exclusion preferences (state taxes, miscellaneous itemized deductions, personal exemptions), and the difference between the actual prior-year AMT and the exclusion-only AMT is the deferral-item portion. Only the deferral-item portion creates a credit.
For ISO exercises, almost all of the AMT is from a deferral preference (the bargain element is a timing item, not an exclusion item), so almost the entire AMT bill becomes a Section 53 credit. For depreciation timing differences, the same is true. For state and local tax add-backs (pre-TCJA), the AMT was attributable to an exclusion item and did not create a credit.
Step two is applying the credit in subsequent years. The credit can offset regular tax in any year that regular tax exceeds tentative minimum tax. The amount of credit usable in a given year is capped at the regular-tax-above-TMT spread. In a year where regular tax equals or falls below TMT (a year with significant AMT preferences or low ordinary income), no credit can be used. In a year where regular tax exceeds TMT by a wide margin (a year with high ordinary income and few preferences), a large amount of credit can be absorbed.
Step three is multi-year planning to generate regular-tax-above-TMT years. This is where alternative minimum tax planning shifts from defense (avoiding the AMT) to offense (recovering the credit). The largest tool is the Roth conversion. Ordinary income from a Roth conversion is fully taxable at regular rates with minimal AMT impact, so the regular-tax-above-TMT spread is wide and the credit is absorbed efficiently. We have used Roth conversion ladders to recover ISO AMT credits over three to five years for clients who would otherwise have seen the credit sit on Form 8801 indefinitely.
Capital gain harvesting is a secondary tool. Long-term capital gains and qualified dividends are taxed at preferential rates inside both the regular tax and the AMT, so the regular-tax-above-TMT spread does not widen much when capital gains are realized. The credit absorption from capital gain harvesting is real but slower than from Roth conversions.
Step four is sale of the original ISO stock. When the stock that produced the original AMT preference is finally sold, the AMT basis is higher than the regular tax basis, which produces a negative AMT adjustment in the year of sale. The negative adjustment widens the regular-tax-above-TMT spread substantially in that year, often allowing a large credit recovery in the year of sale. For a clean fact pattern (exercise in year 1, hold for the required period, sell in year 5 or later), the AMT paid in year 1 is fully recovered in the year of sale. For messier patterns where the stock loses value or is sold over multiple years, the credit recovery is partial in each year and the carryforward continues until exhausted.
Step five is tracking the credit carefully over the years. Section 53 credits do not expire, but they have to be reported on Form 8801 in each subsequent year. Returns prepared without Form 8801 quietly omit the credit, leaving thousands or millions of dollars unrecovered. For taxpayers with prior-year AMT (especially from ISO exercises), confirming that Form 8801 is on the return every year is one of the most important alternative minimum tax planning items.
What does alternative minimum tax planning look like for California residents with the parallel state AMT?
California is one of the few states that imposes its own alternative minimum tax in addition to the federal AMT. California Revenue and Taxation Code Section 17062 establishes the parallel calculation, with its own exemption amounts, phase-out thresholds, and rate structure. Alternative minimum tax planning for California residents has to model both layers simultaneously, because the two calculations interact but do not match.
The California AMT rate is a flat 7% on California AMTI in excess of the exemption. The 2026 California AMT exemption (subject to inflation adjustment) is approximately $46,989 for single filers and $62,650 for MFJ, with phase-outs beginning at $260,000 AMTI for single and $349,000 AMTI for MFJ. The phase-out is at 25 cents per dollar of AMTI above the threshold, so the exemption fully disappears at roughly $448,000 single and $599,000 MFJ.
California AMTI starts with federal AMTI and is then adjusted for California-federal conformity differences. California does not conform to all federal provisions, so several items that are AMT preferences for federal purposes are treated differently for California. The most relevant differences for high-income taxpayers: California does not conform to the federal qualified business income deduction (so QBI is not an AMT add-back for California because it was never a California deduction), California has different depreciation rules in many cases (so the federal-AMT depreciation difference can be different from the California-AMT depreciation difference), and California does not impose an AMT add-back for state income taxes (because California state tax is not a deduction on the California return anyway).
For an ISO exercise, the bargain element is a preference for both federal AMT and California AMT in the same amount. A California resident exercising $1 million of ISO bargain element will face roughly $260,000 of federal AMT (at the 26%/28% rates after exemption) and roughly $65,000 to $70,000 of California AMT (at 7% on the bargain element after the California exemption phase-out). The combined AMT bill of $325,000+ has to be funded from current cash if the stock is illiquid. The two AMT bills are due on the same return cycle: April 15 of the following year.
California also has its own AMT credit under Revenue and Taxation Code Section 17063, which works like the federal Section 53 credit. The California credit is carried forward indefinitely and recovered in future years when California regular tax exceeds California tentative minimum tax. The recovery mechanics parallel the federal credit, with California-specific exemption amounts and rates.
Alternative minimum tax planning for California residents exercising ISOs has to weigh whether to exercise while resident in California or to relocate first. Residency planning is the largest single lever for California taxpayers facing concentrated AMT exposure. A genuine relocation to a no-income-tax state (Texas, Florida, Nevada, Washington, Wyoming, Tennessee, South Dakota) before the exercise eliminates the California AMT layer entirely. The exercise is then subject only to federal AMT (and the eventual sale is subject only to federal capital gains tax, with no California state income tax on the sale).
California’s residency rules are strict, and the Franchise Tax Board challenges high-net-worth residency moves aggressively. A genuine move requires physical presence outside California for at least 183 days, change of driver’s license and voter registration, sale or rental of the California residence, severing business connections, and a documented intent to make the new state a permanent home. A move that happens 30 days before a large ISO exercise will lose at the FTB hearing. A move that happens two years before, with full evidence of a permanent change, can hold up.
An alternative for California residents who cannot relocate is the incomplete non-grantor (ING) trust structure, often domiciled in Nevada or Delaware. The trust is a separate non-California taxpayer, and ISOs transferred to the trust (before exercise, ideally) generate AMT at the trust level under Nevada or Delaware rules rather than at the California level. The mechanics are technical, California has been actively litigating the boundaries, and the planning has to be done years before the exercise, not weeks. We work with specialist trust counsel on these structures for clients who have meaningful California AMT exposure and cannot move.
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