Equity Compensation · IRC §55 · Form 6251 · TY 2026
How the alternative minimum tax works in 2026, why ISO exercises trigger it, what the OBBBA phase-out doubling means, and how to recover AMT through the Form 8801 minimum tax credit.
Want to estimate your AMT instantly? Open the calculator and run your inputs.
Open the AMT Calculator →The alternative minimum tax (AMT) is a parallel federal tax computed on Form 6251 under IRC section 55. You add back AMT preference items (most importantly the bargain element on incentive stock options held past year-end), subtract an exemption that phases out at high AMTI, and apply 26 or 28 percent rates. You pay the higher of regular tax or tentative minimum tax. OBBBA section 70107 reset the 2026 phase-out threshold to 1,000,000 dollars MFJ and doubled the phase-out rate from 25 to 50 percent, which significantly expands AMT exposure for high earners and ISO exercisers.
The alternative minimum tax (AMT) is a separate federal tax system codified in IRC section 55. It runs in parallel with the regular income tax. Every year, taxpayers above certain income levels must compute their tax under both systems and pay whichever is higher. The AMT was originally enacted in 1969 after Congress discovered that 155 high-income households had paid zero federal income tax by stacking deductions and tax preferences. The current structure dates to the Tax Reform Act of 1986 and has been revised many times since.
AMT operates on a wider base than the regular tax. It disallows or limits certain deductions (state and local taxes, the standard deduction, miscellaneous itemized deductions before TCJA), adds back certain preference items (incentive stock option bargain elements, accelerated depreciation, percentage depletion, certain private activity bond interest), and applies a flat 26 or 28 percent rate after a generous exemption is subtracted. Long-term capital gains and qualified dividends keep their preferential rates under AMT, but they still expand the AMTI base and can erode the exemption.
For tax years 2018 through 2025, the TCJA dramatically increased the AMT exemption and phase-out thresholds, which collapsed the number of AMT payers from roughly 5 million in 2017 to under 200,000 in recent years. OBBBA (P.L. 119-21) made the elevated TCJA exemption permanent but reset the phase-out threshold and doubled the phase-out rate beginning in 2026 - so the population of AMT payers will expand again, particularly among high-earning W-2 households exercising ISOs.
The AMT computation has six steps. Each is performed on Form 6251.
If your tentative minimum tax is less than or equal to your regular tax, you owe no AMT. You still file Form 6251 if you have any of the listed preferences or adjustments, even if no AMT is ultimately due, because the form documents the calculation and supports any minimum tax credit carryforward.
The regular tax system rewards specific behaviors (state-tax payments, depreciation acceleration, certain types of investment income). The AMT was designed to claw back a portion of those rewards from taxpayers who would otherwise pay very little tax. Because AMT applies a flat rate after a single exemption, it cannot be reduced through stacking deductions - if you trigger it, you pay it.
OBBBA section 70107 made two structural changes to the AMT effective for tax years beginning after December 31, 2025. Both reduce the protection that the TCJA-era AMT framework offered to upper-middle-income households and ISO exercisers.
Change 1 - Phase-out threshold reset. Under the TCJA, the AMT exemption phase-out threshold for joint filers had risen with inflation to approximately 1,252,700 dollars by 2025. OBBBA reset the MFJ threshold back to 1,000,000 dollars (with the single/HOH/MFS threshold at 500,000 dollars). The reset alone exposes more high-income filers to the phase-out range.
Change 2 - Phase-out rate doubles. The previous phase-out rate was 25 percent of AMTI over the threshold. OBBBA doubles this to 50 percent. The combined effect creates a "bump zone" where every additional dollar of AMTI above the threshold increases the AMT base by 1.50 dollars (the dollar itself plus 50 cents of lost exemption). Multiplied by the 26 or 28 percent AMT rates, the effective marginal rate inside the phase-out band is roughly 39 percent (26% × 1.5) or 42 percent (28% × 1.5).
For a single filer, the 2026 exemption of 90,100 dollars phases out completely when AMTI reaches 680,200 dollars (500,000 plus 90,100/0.5). For MFJ, full phase-out occurs at AMTI of 1,280,400 dollars. Above the full phase-out point, the AMT bump zone marginal rate disappears and the AMT acts like a flat 28 percent (with LTCG carve-outs).
| Filing Status | Exemption | Phase-out Start (AMTI) | Fully Phased Out (AMTI) |
|---|---|---|---|
| Single / HOH | $90,100 | $500,000 | $680,200 |
| MFJ / QSS | $140,200 | $1,000,000 | $1,280,400 |
| MFS | $70,100 | $500,000 | $640,200 |
The single most common AMT trigger for individual filers is exercising an incentive stock option (ISO) and holding the shares past December 31 of the exercise year. IRC section 56(b)(3) treats the bargain element - the FMV at exercise minus the exercise price - as an AMT preference item. The preference is added to AMTI even though no cash changes hands and no regular-tax income is recognized.
The trap: you pay AMT on phantom income. If you exercise 5,000 ISOs at a 20-dollar strike when the FMV is 80 dollars per share, the bargain element is 300,000 dollars. That entire amount flows to AMTI as a positive adjustment if you do not sell the shares in the same calendar year. You then owe AMT on the 300,000 even though the cash to pay it is not in your bank account - you are still holding shares.
For regular tax purposes, ISOs are not taxed at exercise. The shares carry your exercise price as basis, and when you sell them more than 2 years from grant and more than 1 year from exercise (a qualifying disposition), the entire gain is long-term capital gain. AMT does not honor this favorable timing. AMT treats the exercise as a recognition event and pulls the spread into AMTI immediately.
If you sell the ISO shares in the same calendar year as exercise - even one day after - the section 56(b)(3) preference disappears. The exercise becomes a disqualifying disposition under regular tax rules, and the spread is reported as ordinary W-2 wages by your employer. Since the same income now hits regular taxable income, there is no AMT preference to add. This is why "same-year exercise and sell" is the most common practical strategy when an ISO would otherwise trigger AMT - you trade a long-term capital gain rate (potentially 20 percent at sale) for an ordinary rate now (up to 37 percent), but you avoid the AMT cash crunch on phantom income.
Your employer must issue Form 3921, Exercise of an Incentive Stock Option Under Section 422(b), after each ISO exercise. The form reports the exercise date, exercise price per share, FMV per share on exercise, and number of shares transferred. You use these numbers to compute the AMT bargain element and your AMT basis in the shares (which differs from your regular-tax basis - the AMT basis equals the FMV at exercise, while the regular-tax basis stays at the exercise price). Keep all Form 3921s; the AMT/regular basis difference matters for years to come when you sell the shares and reverse the AMT preference.
The 2026 AMT exemption is the dollar amount of AMTI shielded from AMT before the 26/28 percent rates apply. Per Rev. Proc. 2025-32 and OBBBA §70107:
The phase-out reduces the exemption by 50 cents for every dollar of AMTI above the threshold (the new OBBBA rate). The exemption cannot go below zero.
Reduced exemption = max(0, base exemption - 0.50 × (AMTI - threshold))
For a single filer with 600,000 dollars of AMTI: 600,000 - 500,000 = 100,000 over threshold. 0.50 × 100,000 = 50,000 reduction. Exemption = 90,100 - 50,000 = 40,100. AMT taxable excess = 600,000 - 40,100 = 559,900. The bump-zone marginal rate on that next dollar of AMTI is 39 percent (26 percent on the new dollar plus 26 percent on the 50-cent exemption loss).
The exemption hits zero when the phase-out reduction equals the base exemption. For single, that is 90,100 / 0.5 = 180,200 dollars above the 500,000 threshold, or AMTI of 680,200. For MFJ: 140,200 / 0.5 = 280,400 above the 1,000,000 threshold, or AMTI of 1,280,400. Above those points, all of AMTI is subject to the 26/28 percent rates with no exemption at all.
AMT applies a two-rate structure to the AMT taxable excess (AMTI minus exemption). For 2026 per Rev. Proc. 2025-32:
These rates apply to ordinary AMTI components only. Long-term capital gains and qualified dividends keep their preferential rates (0, 15, or 20 percent for 2026 per Rev. Proc. 2025-32) under AMT. The Form 6251 calculation extracts the LTCG/QD layer, taxes it at the preferential rates, and applies 26/28 percent only to the remaining AMTI portion.
The sum of these rate components is the tentative minimum tax. AMT owed equals TMT minus regular tax (limited to zero - you cannot have negative AMT). If your regular tax is already higher than your TMT, you owe no AMT. The Form 6251 worksheet flows directly into Schedule 2, line 1 of Form 1040.
Inside the exemption phase-out range (AMTI between the threshold and the full phase-out point), each dollar of AMTI also reduces the exemption by 50 cents. Multiplied by the 26 or 28 percent rate, the effective marginal AMT rate inside the bump zone is approximately 39 percent (26% × 1.5) on AMTI in the 26-percent layer and approximately 42 percent (28% × 1.5) on AMTI in the 28-percent layer. Above the full phase-out point, the bump disappears and the rate returns to 28 percent.
AMT redefines taxable income by adding back certain regular-tax deductions (adjustments) and certain regular-tax exclusions (preferences). The most common items for individual filers:
If you took the standard deduction on your regular return, you must add it back for AMT. For 2026, that is 16,100 dollars single/MFS, 32,200 dollars MFJ/QSS, or 24,150 dollars HOH. AMT does not allow the standard deduction. If you itemized, this add-back does not apply, but specific itemized deductions are added back instead.
State and local income taxes, state property taxes, and any other taxes deducted on Schedule A line 5 are fully added back to AMTI. The OBBBA-era 40,000-dollar SALT cap on the regular return reduces this exposure compared to pre-2018 levels, but every dollar of SALT deducted on the regular return is still a dollar added to AMTI.
Per IRC §56(b)(3), the bargain element on ISOs exercised and held past year-end is added to AMTI. If shares are sold in the same calendar year, this adjustment is reversed (the regular-tax disqualifying disposition wages already reflect the spread).
Tax-exempt interest from private activity bonds (PABs) issued in non-exempt years is taxable for AMT purposes even though it is exempt for regular tax. Bonds issued in 2009 and 2010 under the American Recovery and Reinvestment Act are generally exempt from this AMT preference. PAB interest is reported in Box 9 of Form 1099-INT.
Depreciation on certain post-1986 property is computed using a different (slower) method for AMT than for regular tax. The difference is an adjustment - positive in early years, often negative in later years as the AMT depreciation catches up. Most W-2 employees do not have this adjustment unless they own rental real estate or unincorporated business assets.
Form 6251, Alternative Minimum Tax - Individuals, is the IRS form used to compute and report AMT. It runs about three dozen lines. The structural flow:
If you exercised ISOs during the year, you must include Form 3921 numbers on Form 6251 line 2i. If you sold shares for which you previously paid AMT, you must adjust your AMT basis - this is where Form 6251 line 2k (disposition of property) comes in, and where Form 8801 (next section) becomes important for recovering the credit.
You must file Form 6251 if any of the following apply: line 7 of Form 6251 is greater than line 10 (AMT is owed); you claim certain credits (Form 8801 minimum tax credit); you have AMT preference items even if no AMT is owed (ISO exercises, depreciation adjustments, PAB interest); or your AMTI exceeds the exemption amount. In practice, most tax software computes Form 6251 automatically whenever any preference is present.
AMT is sometimes recoverable. IRC section 53 provides a minimum tax credit (MTC) reported on Form 8801, Credit for Prior Year Minimum Tax - Individuals, Estates, and Trusts. The credit equals the AMT paid in prior years that arose from deferral preferences and is applied against future regular tax in years when regular tax exceeds the tentative minimum tax. The credit carries forward indefinitely.
Not all AMT generates a credit. The AMT preferences are split into two categories:
Form 8801 separates the two types and tracks only the deferral portion as MTC. If your AMT was driven purely by SALT add-back and standard deduction (typical for high-income W-2 households without ISOs), no credit accrues. If your AMT was driven by an ISO exercise, the entire AMT amount is generally a deferral preference and credits forward.
In a future year when your regular tax exceeds your tentative minimum tax, you can apply the MTC up to the difference. ISO-driven AMT typically recovers within 5 to 10 years as you sell the underlying shares. When you sell, the regular-tax basis (exercise price) creates a large regular-tax capital gain, but the AMT basis (FMV at exercise) creates a smaller AMT capital gain. The difference produces a year where regular tax greatly exceeds TMT - the perfect year to use the credit.
Maya pays 90,762 dollars of AMT in year 1 from an ISO exercise (full scenario in the next section). Her regular-tax basis in the shares is 100,000 dollars (exercise price × 5,000 shares). Her AMT basis is 400,000 dollars (FMV at exercise × 5,000 shares). In year 5 she sells all 5,000 shares for 600,000 dollars. Regular-tax LTCG = 500,000 (600,000 minus 100,000). AMT LTCG = 200,000 (600,000 minus 400,000). The 300,000-dollar difference in AMT income reduces her tentative minimum tax in year 5 by approximately 78,000 dollars (26-28% × 300,000). If her regular tax exceeds TMT by at least 78,000 in year 5, she uses 78,000 of her MTC. The remaining 12,762-dollar credit carries forward.
AMT exposure is rarely accidental for sophisticated taxpayers - it usually follows from a deliberate decision (exercising ISOs, deducting a large state tax bill, owning real estate with accelerated depreciation). Several strategies reduce or shift AMT impact.
Because AMT and regular tax are computed annually with different brackets, shifting income or deductions between adjacent years can change which system controls. If your regular tax already exceeds your TMT in the current year, moving more income into the current year (such as a Roth conversion or accelerated capital gain) can use up regular-tax capacity without triggering AMT. Conversely, in an AMT year, deferring deductible expenses (charitable contributions, deductible state tax estimated payments) to a future regular-tax year preserves their value, since AMT often disallows or limits them.
If you have a large ISO grant, exercising it across multiple years rather than all at once can keep the bargain element below the AMT exemption phase-out threshold. The "AMT crossover" exercise amount - the largest exercise that produces AMTI just below your tentative minimum tax break-even - lets you exercise without triggering AMT cash. The AMT calculator can identify your specific crossover amount.
If you must exercise but cannot afford the AMT cash, exercising and selling in the same calendar year (a disqualifying disposition) eliminates the AMT preference. The cost is converting long-term capital gain treatment into ordinary W-2 wages - higher rate, but no AMT cash crunch on phantom income.
Pre-tax 401(k) and traditional IRA contributions reduce AMTI dollar-for-dollar (subject to deductibility rules). For high earners in the AMT phase-out bump zone, this is one of the most efficient ways to drop AMTI back toward the threshold. Roth contributions do not help with AMT in the contribution year (they are after-tax), but they reduce future AMTI by replacing future taxable distributions.
Charitable contributions are allowed against both regular tax and AMT. In a high-AMT year, accelerating multi-year charitable giving into a single year (often through a donor-advised fund) maximizes the deduction value while regular tax is still controlling and avoids stacking deductions in years when AMT controls.
If you hold municipal bonds and might be exposed to AMT, avoid private activity bonds (PABs) issued in non-exempt years. Their interest is taxable for AMT despite being tax-exempt for regular tax. General obligation bonds and PABs from 2009-2010 ARRA issuances do not create AMT preference.
The most expensive AMT mistake clients make with ISOs is exercising late in Q4 with the intent to "decide later" whether to hold. Once December 31 passes, the AMT preference locks in. If the stock then drops in the new year, the client owes AMT on a paper gain they no longer have - often six figures of cash for shares now worth less than the tax bill. The fix is structural: decide in advance whether the exercise is a "hold for LTCG" play or a "same-year sell" play, and execute the sale before December 31 if the latter. Never exercise in late December without a clear hold-or-sell decision pre-committed and a cash plan for the AMT if holding. The OBBBA phase-out doubling makes this trap more punishing in 2026 because the bump-zone marginal rate now hits a wider band of upper-middle-income exercisers.
Maya is a single software engineer with 250,000 dollars of W-2 wages. In March 2026 she exercises 5,000 ISOs at her 20-dollar strike price. The FMV on exercise day is 80 dollars per share. She decides to hold the shares to qualify for long-term capital gain treatment and does not sell before December 31. Her bargain element is (80 - 20) × 5,000 = 300,000 dollars. She also paid 20,000 dollars of state income tax (Schedule A, capped) and took the standard deduction was not feasible because itemizing helped her - so she itemizes and adds back the 20,000 SALT.
Regular-tax computation: Taxable income approximately 234,000 dollars after itemized deductions. Regular tax on 234,000 single 2026 (estimated using Rev. Proc. 2025-32 brackets) is approximately 48,562 dollars.
AMT computation: AMTI = regular taxable income 234,000 + standard deduction equivalent or itemized adjustments + SALT add-back 20,000 + ISO bargain element 300,000 = 554,000. (Adjusted for the standard-deduction line item: assume net AMTI of 570,100 after all preferences are added back.) AMTI of 570,100 exceeds the 500,000 single phase-out threshold by 70,100. Phase-out reduction = 0.50 × 70,100 = 35,050. Reduced exemption = 90,100 - 35,050 = 55,050. AMT taxable excess = 570,100 - 55,050 = 515,050. TMT = 244,500 × 0.26 + (515,050 - 244,500) × 0.28 = 63,570 + 75,754 = 139,324.
Recovery in future years: Maya files Form 8801 to track her 90,762-dollar minimum tax credit. Her AMT basis in the 5,000 shares is 80 dollars per share (FMV at exercise) = 400,000. Her regular-tax basis is 20 dollars per share = 100,000. When she eventually sells the shares (assume year 5 at 600,000 dollars total), her regular-tax LTCG is 500,000 and her AMT LTCG is 200,000. The 300,000-dollar AMT-vs-regular gap reduces her year-5 TMT by approximately 78,000 dollars - leaving regular tax higher than TMT and creating room to apply 78,000 of the MTC. The remaining 12,762-dollar credit carries to year 6 and beyond. Over time, Maya recovers the full 90,762 - but the cash was tied up for years, and the timing was driven by when she chose to sell.
Pull your Form 3921 and compute the bargain element (FMV at exercise minus exercise price, times shares held). Add it to AMTI on Form 6251 line 2i. Run the full Form 6251 calculation - exemption with 50% phase-out, 26/28% rates, capital gains carve-out. Compare TMT to regular tax. If AMT is owed, plan the cash payment by April 15 and start a Form 8801 carryforward log. Use the AMT Calculator to model the federal exposure before filing.
The 50% phase-out under OBBBA may pull you into AMT even without ISOs. Add back state and local taxes deducted on Schedule A and the standard deduction (if claimed) to arrive at AMTI. If your AMTI is in the 500,000 to 680,200 range (single) or 1,000,000 to 1,280,400 (MFJ), you are in the bump zone with effective marginal rates near 39-42%. There is no minimum tax credit for SALT-driven AMT - it is a permanent cost. Plan deduction timing across years to avoid stacking SALT in AMT years.
Run the AMT crossover calculation before exercising. The crossover is the largest exercise that produces tentative minimum tax equal to your regular tax, so no AMT cash is due. Spreading exercises across multiple years can keep each year below the crossover. If a single-year exercise would exceed the crossover by a wide margin, consider a same-year disqualifying disposition - the preference disappears, the spread becomes W-2 wages, and there is no AMT cash crunch on phantom income. The AMT Calculator identifies your crossover point.
Disclaimer: This guide is for informational and educational purposes only. It does not constitute tax, legal, or financial advice. Tax rules are complex and individual circumstances vary. Consult a qualified tax professional before making decisions based on this content. Tax laws are subject to change. National Tax Tools is not a tax advisory firm.