How AMT worked with accelerated depreciation before TCJA
Before the Tax Cuts and Jobs Act of 2017 (TCJA), the Alternative Minimum Tax (AMT) was a significant trap for investors who took accelerated depreciation. Under the old system, individuals had to add back the difference between the faster MACRS depreciation and the slower Alternative Depreciation System (ADS) depreciation when computing Alternative Minimum Taxable Income (AMTI). This depreciation preference item could push taxpayers into the AMT, partly offsetting the benefit of accelerated deductions.
A cost segregation study that reclassified assets into shorter lives — generating large accelerated deductions — could simultaneously create a large AMT preference item, reducing the net benefit of the study.
What TCJA changed: the AMT for individuals is largely neutralized
The TCJA dramatically increased the individual AMT exemption to $137,000 for married filing jointly in 2024 (indexed for inflation), and raised the exemption phase-out threshold to $1,237,450 MFJ. As a result, the vast majority of individual real estate investors no longer pay AMT even with large cost segregation deductions.
Additionally, TCJA changed the depreciation adjustment: qualified bonus depreciation no longer creates an AMT preference item for individuals. The accelerated deduction from bonus depreciation (which is the primary benefit from cost segregation) does not add back to AMTI under current law. Straight-line MACRS deductions (without bonus depreciation) also generally do not trigger AMT adjustments for real property.
Bottom line for most individual investors: AMT is no longer a meaningful impediment to cost segregation. Model your specific situation, but for most investors, the TCJA reforms removed this concern.
Corporate AMT and the CAMT: a newer concern
The Inflation Reduction Act of 2022 introduced a new Corporate Alternative Minimum Tax (CAMT), effective for tax years beginning after 2022, imposing a 15% minimum tax on the adjusted financial statement income of corporations with average annual adjusted financial statement income exceeding $1 billion. This is a concern only for large, publicly traded corporations — not for most real estate investors holding property through LLCs, S-corps, or as individuals.
For individual investors and small entities, the CAMT does not apply. If you own property through a corporate structure large enough to trigger CAMT concerns, work with a tax professional who can model the CAMT and regular tax interaction for your specific cost segregation deductions.
Where AMT can still apply: electing out of bonus
The key survival of the depreciation preference is this: bonus depreciation is exempt from the AMT adjustment, but regular accelerated MACRS is not. For personal property — the 5- and 7-year assets a cost seg study identifies — regular MACRS uses the 200% declining-balance method, while the AMT system requires 150% declining balance over the same recovery period. If you elect out of bonus depreciation and instead depreciate those components with regular accelerated MACRS, you can create a positive AMT depreciation adjustment on Form 6251.
In other words, taking bonus depreciation avoids the AMT depreciation adjustment entirely, while electing out and using accelerated MACRS can revive it. With 100% bonus depreciation restored for qualified property placed in service after January 19, 2025, most cost seg investors take bonus and never touch the AMT depreciation preference. The adjustment matters mainly for those who deliberately elect out of bonus depreciation.
Other AMT preferences that can interact with a big deduction year
Even though the depreciation preference is usually neutralized, a cost segregation study can push you into an unusual tax year with a large loss — and other AMT items can still surface. Incentive stock option exercises, certain private-activity bond interest, and differences between regular-tax and AMT treatment of some deductions remain AMT preferences. A year with a very low regular-tax liability (because a cost seg loss wiped out taxable income) can make your tentative minimum tax the higher number, so AMT applies.
Since 2018, the state and local tax deduction — historically the biggest AMT trigger for real estate investors — is capped at $10,000 for regular tax and simply not allowed for AMT, so it rarely swings the result the way it once did. Still, run Form 6251 in any year with an outsized deduction; the interaction is fact-specific.
A worked example
Suppose a cost seg study on a $2,000,000 building lets you elect out of bonus and claim $300,000 of accelerated MACRS on 5- and 7-year components in year one. For the AMT, those same components are depreciated at 150% declining balance, yielding perhaps $260,000. The $40,000 difference is a positive AMT adjustment added back to your AMT income for the year — potentially exposing you to AMT if your other preferences and income line up.
Had you instead taken 100% bonus depreciation on the same $300,000, there would be no AMT depreciation adjustment — bonus is respected for both regular tax and AMT. In later years the pattern reverses: the AMT allows more depreciation than regular tax once the regular 200% method slows, creating negative adjustments. The lifetime totals converge, but the timing can trigger AMT in the front-loaded year if you elected out of bonus.
AMT has its own passive losses, NOLs, and credits
A large cost segregation loss often runs into the passive activity loss rules, and the AMT computes passive losses on a separate track using AMT depreciation figures. Your allowed passive loss for AMT can differ from the regular-tax figure, and suspended passive losses carry forward with their own AMT amount. Similarly, a net operating loss created in part by accelerated depreciation must be recomputed as an 'alternative tax NOL' for AMT, which can limit how much of the loss shelters AMT income.
The practical point: in a year dominated by a cost seg deduction, your regular-tax and AMT pictures can diverge in several places at once — depreciation, passive losses, and NOLs. This is exactly the scenario where preparing Form 6251 alongside the regular return, rather than as an afterthought, prevents a surprise minimum-tax bill.
How to tell whether you're exposed, and what to do
AMT liability is computed on Form 6251: you start with regular taxable income, add back preferences and adjustments (including any elected-out accelerated depreciation), subtract the AMT exemption, and compare the resulting tentative minimum tax to your regular tax. You pay the higher of the two. For 2024, the exemption is roughly $85,700 (single) and $133,300 (married filing jointly), phasing out at high income — figures indexed annually.
If a cost seg study will generate a large deduction, model Form 6251 in advance. Two levers help: take bonus depreciation rather than electing out (removing the depreciation preference), and time other AMT preferences such as ISO exercises into different years. AMT paid because of a timing preference can generate a minimum tax credit (Form 8801) usable in future years, so the cost may be partly recovered — another reason to keep a multi-year model.
State add-back rules and the corporate picture
Beyond the federal AMT, several states decouple from federal bonus depreciation and require you to add back some or all of the bonus deduction in computing state taxable income, then allow it back over the asset's remaining life. States that have historically decoupled include California — which does not conform to bonus depreciation at all — along with others that partially decouple. This is not the federal AMT, but it produces a similar timing effect: the first-year state deduction from a cost seg study can be far smaller than the federal one, with the difference recovered over future years. Model your state's conformity separately from the federal calculation.
On the entity side, remember that the regular corporate AMT was repealed by the TCJA for tax years after 2017, so ordinary C-corps no longer face an AMT depreciation adjustment at all; only the new CAMT on billion-dollar corporations remains, and it works off financial-statement income rather than tax depreciation. For the vast majority of real estate investors — individuals, LLCs, S-corps, and small C-corps — the federal AMT is a non-issue for cost segregation as long as bonus depreciation is claimed. The live questions are usually state decoupling and whether the loss can actually be used, not the federal minimum tax.
Frequently asked questions
Does bonus depreciation from a cost seg study trigger the AMT?
Under current law (TCJA), bonus depreciation generally does not create an AMT preference item for individual taxpayers. The TCJA largely neutralized AMT for individuals with higher exemptions.
Who should be concerned about AMT and cost segregation?
Individuals with very high income near or above the AMT phase-out thresholds, and corporations with adjusted financial statement income over $1 billion (CAMT). Most small-to-mid rental investors don't need to worry.
What is the AMT depreciation adjustment for real property?
Under current law, straight-line MACRS depreciation on real property generally doesn't create an AMT adjustment. The prior rules that required ADS adjustment for accelerated real property depreciation were largely addressed by TCJA.
Does electing out of bonus depreciation create an AMT adjustment?
It can. Bonus depreciation is exempt from the AMT depreciation adjustment, but regular accelerated MACRS on 5- and 7-year property uses 200% declining balance for regular tax and only 150% for AMT. Electing out and using accelerated MACRS revives that difference as an AMT adjustment.
Is there a minimum tax credit for AMT paid on depreciation?
Yes. AMT caused by timing preferences like accelerated depreciation generally generates a minimum tax credit (Form 8801) that can offset regular tax in later years, so the cost of a timing-driven AMT is often recovered over time.
Did the SALT cap reduce AMT exposure for real estate investors?
Yes. The state and local tax deduction was historically the biggest AMT trigger. Since 2018 it is capped at $10,000 for regular tax and disallowed for AMT, which — combined with much higher exemptions — removed AMT as a concern for most individual investors.
Sources
Educational information and estimates only. Not tax advice. Tax rules change and vary by situation; consult a qualified tax professional before acting.