Cost segregation is how many net lease investors accelerate depreciation. Without a study, a commercial building is depreciated straight-line over 39 years. A study identifies components that belong in shorter 5-, 7-, and 15-year classes, and under the One Big Beautiful Bill Act, qualifying property acquired after January 19, 2025 is eligible for 100% bonus depreciation, so those components can be deducted in the year the property is placed in service. This guide explains how studies work, what they cost, when to order one, which property types reclassify the most, and the limits investors often overlook. For background on investment grade net lease investing, see the investment grade guide.
General information, not tax advice. Benefits depend on your tax situation; have a CPA model them before you rely on them.
What Is a Cost Segregation Study?
A cost segregation study is an engineering-based analysis that allocates a property’s cost among depreciation classes. The IRS publishes a Cost Segregation Audit Techniques Guide that its examiners use to evaluate studies; it describes what a well-documented study looks like, but the IRS does not approve individual studies in advance. A study’s value under examination depends on its methodology and documentation.
| Category | Recovery period | Typical examples | Bonus depreciation eligible? |
|---|---|---|---|
| Personal property | 5 or 7 years | Certain specialized equipment, decorative fixtures, dedicated electrical for equipment | Yes |
| Land improvements | 15 years | Paving and parking, landscaping, fencing, site lighting, signage, sidewalks | Yes |
| Qualified improvement property | 15 years | Certain interior improvements to nonresidential buildings made after the building was first placed in service | Yes |
| Building | 39 years | Structure, roof, walls, and building systems | No |
| Land | Not depreciable | Land, including land under a ground lease | No |
Costs and Benefits
Study fees vary with property size and complexity; for single-tenant net lease properties they are often several thousand dollars to the low tens of thousands. The benefit is mainly timing: cost segregation moves deductions earlier, it does not create new deductions. The value of that acceleration depends on:
- Whether you can use the deductions. Rental losses are generally passive and can offset only passive income unless you qualify as a real estate professional and materially participate, or you have other passive income.
- Your tax rate now and when the property is sold.
- How long you hold and what you do at sale. Depreciation is generally recaptured on a taxable sale: personal property (Section 1245) at ordinary income rates, and real property depreciation at up to 25%.
- The incremental amount compared with straight-line depreciation you would have taken anyway.
Illustration: on a $1,500,000 purchase with 20% allocated to land, the depreciable basis is $1,200,000. If a study reclassifies 25% of that basis ($300,000) into bonus-eligible classes, year-one depreciation rises from about $29,500 under straight-line to about $322,000 (the $300,000 bonus plus straight-line on the remaining $900,000 building basis, for a property placed in service in January under the mid-month convention). For an investor who can use the extra deduction at a 37% rate, that is roughly $108,300 of tax deferred in year one, offset over time by lower future depreciation and by recapture on a taxable sale.
Whether a study is worth it is a case-by-case question for your CPA, not a rule of thumb based on property value.
When to Order a Study
At acquisition. Ordering soon after closing lets the depreciation schedule be set up for the first tax return. Some investors engage a firm during due diligence.
After new construction. Contractor cost detail makes allocation more precise.
Retroactively. If you own a property and never had a study, a look-back study can usually be implemented through an accounting method change on Form 3115, taking the missed depreciation as a Section 481(a) adjustment in the current year rather than amending prior returns. Bonus depreciation for older assets follows the rules in effect when they were placed in service, so the 100% rate generally applies only to property acquired after January 19, 2025.
The Study Process
- Documents: purchase agreement, closing statement, appraisal, construction documents if available, and any prior depreciation schedules.
- Site inspection: an engineer documents building systems, site improvements, and equipment. With a tenant in place, access may need to be coordinated.
- Analysis: components are classified and costed.
- Report: an asset listing, depreciation schedule, and methodology support for your tax return and any examination.
Many studies take several weeks; ask about timing if you need the report for a filing deadline.
Reclassification by Property Type
The share of cost that can be reclassified varies widely. These ranges are general industry estimates for discussion, not guarantees; the study determines the actual result.
| Property type | Commonly cited reclassification range | Notes |
|---|---|---|
| Car washes | Often high | Much of the cost is equipment and site work; see our car wash guide |
| Gas stations and convenience stores | Often high | Some qualify as 15-year retail motor fuel outlets; see our gas station guide |
| Quick-service restaurants and auto service | Moderate | See our QSR and auto service guide |
| Medical, dialysis, and dental | Moderate | See our medical guide |
| Dollar stores, pharmacies, auto parts stores | Lower | Mostly building shell with some site work |
| Bank branches | Lower | Mostly building shell |
| Ground leases (land only) | None | Land is not depreciable |
For the full ranking by tenant, see best NNN tenants for bonus depreciation.
Common Misconceptions
“Cost segregation is aggressive.” A well-documented, engineering-based study is an accepted method of allocating cost. Aggressive classifications or thin documentation are what create examination risk.
“Recapture cancels the benefit.” Not usually, because deferral has time value, but recapture is real. A 1031 exchange can defer gain on real property, but since 2018 Section 1031 applies only to real property, so depreciation recaptured on components classified as personal property (Section 1245) is generally not deferred by an exchange, and Section 1250 rules can also apply depending on the replacement property. How much is deferred depends on how the sale price is allocated and what you acquire; have your CPA model it before the sale. Inherited property generally receives a basis adjustment at death, which can eliminate deferred gain for heirs under current law.
“It only works for new construction.” Studies also apply to acquisitions of existing buildings and to renovations.
Choosing a Firm
- Engineering-based methodology with documented cost sources.
- A physical site inspection rather than a desktop-only estimate.
- Experience with your property type, such as car washes or fuel sites.
- Clear documentation you and your CPA can rely on if the return is examined.
Frequently Asked Questions
What is cost segregation for NNN properties?
An engineering-based study that allocates a property’s cost among depreciation classes, moving eligible components from the 39-year building class into 5-, 7-, or 15-year classes that can qualify for bonus depreciation.
Is a cost segregation study IRS approved?
The IRS does not approve individual studies. It publishes an Audit Techniques Guide its examiners use to evaluate studies, and a study’s strength depends on its methodology and documentation.
Does a 1031 exchange defer all depreciation recapture?
Not necessarily. Section 1031 applies only to real property, so recapture on components classified as personal property is generally not deferred, and other recapture rules can apply depending on the replacement property. Have a CPA model the sale allocation.
Can I do a study on a property I already own?
Yes. A look-back study can usually be implemented with an accounting method change on Form 3115, taking missed depreciation in the current year without amending prior returns.
Is cost segregation always worth it?
No. The benefit is earlier deductions, and its value depends on whether you can use the deductions, your tax rates, your holding period, and recapture at sale. Ask a CPA to compare the incremental benefit with the study fee.
Evaluating Depreciation on Your Next Acquisition?
We can flag which properties tend to support more accelerated depreciation and coordinate with your CPA and cost segregation firm before you close.
Related Depreciation Guides
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