When it comes to cost segregation studies explained: how, understanding the fundamentals is key. If you own rental property or commercial real estate and you are depreciating the entire building over 27.5 or 39 years, you are leaving serious money on the table. A cost segregation study is one of the most powerful — and most underused — tax strategies available to real estate investors. It can generate $50,000 to $100,000 or more in accelerated deductions in the very first year.
Understanding Cost Segregation Studies Explained: How in 2026
At AE Tax Advisors, we perform cost segregation studies for clients across the country. Here is everything you need to know about how cost seg works and whether it makes sense for your properties.
What Is a Cost Segregation Study?
A cost segregation study is an engineering-based analysis that identifies components of a building that can be reclassified from the standard 27.5-year (residential) or 39-year (commercial) depreciation schedule into shorter recovery periods: 5-year, 7-year, or 15-year property under the Modified Accelerated Cost Recovery System (MACRS).
Instead of depreciating your entire building slowly over decades, cost segregation allows you to front-load depreciation deductions by separating out components like flooring, cabinetry, appliances, landscaping, parking lots, plumbing fixtures, electrical systems, and more.
How Does Cost Segregation Work?
The process involves a detailed review of your property, including construction documents, appraisals, inspection reports, and photographs. An engineer or qualified professional identifies every component of the building and classifies each one into the appropriate MACRS recovery period.
5-Year Property
This category includes items like appliances, carpet, certain electrical components, cabinetry, decorative fixtures, and personal property items used in the rental. These components can be depreciated over just 5 years instead of 27.5 or 39 years.
7-Year Property
Office furniture, certain machinery, and specialty equipment fall into the 7-year category. For commercial properties, this can include items like movable partitions and specialized systems.
15-Year Property
Land improvements such as landscaping, parking lots, sidewalks, fencing, drainage systems, and exterior lighting are classified as 15-year property. These are often a significant portion of the total reclassification.
Example: Cost Segregation on a $500,000 Rental Property
Let us walk through a typical example. You purchase a residential rental property for $500,000 (excluding land value). Without cost segregation, you would depreciate the entire building over 27.5 years, generating approximately $18,182 per year in depreciation deductions.
With a cost segregation study, the breakdown might look something like this:
5-year property: $75,000 (15% of building value) — items like flooring, appliances, fixtures, cabinetry
7-year property: $15,000 (3% of building value) — furniture, specialty items
15-year property: $50,000 (10% of building value) — landscaping, sidewalks, fencing, exterior lighting
Remaining 27.5-year property: $360,000 (72% of building value) — structural components
In Year 1, using current bonus depreciation rates and accelerated MACRS schedules, you could potentially claim $70,000 to $100,000 in depreciation deductions — compared to just $18,182 under straight-line depreciation. That is a difference of $50,000 to $80,000 in additional deductions in the first year alone.
Who Benefits Most From Cost Segregation?
Residential Rental Property Owners
If you own single-family rentals, duplexes, triplexes, or small multifamily buildings, cost segregation can significantly accelerate your depreciation deductions.
Short-Term Rental (STR) Operators
STR owners who materially participate in their rental activity can use cost segregation to generate non-passive losses that offset W-2 and other active income. This is the foundation of the STR tax loophole that has saved our clients hundreds of thousands of dollars.
Commercial Property Owners
Office buildings, retail spaces, warehouses, and other commercial properties often have an even higher percentage of components that can be reclassified into shorter recovery periods.
Recently Purchased Properties
Cost segregation is most impactful in the year of purchase or the year the study is completed. However, it is never too late — we can perform lookback cost segregation studies on properties purchased in prior years.
Lookback Cost Segregation: It Is Not Too Late
If you purchased a property years ago and never had a cost segregation study done, you can still benefit. A lookback cost segregation study allows you to claim all of the accelerated depreciation you missed in a single year, without filing amended returns. This is done through a Form 3115 (Change in Accounting Method), which the IRS specifically allows for this purpose.
This means if you bought a property five years ago and have been using straight-line depreciation, we can perform a cost segregation study today and claim the cumulative difference in depreciation as a single catch-up deduction on your current-year return.
Bonus Depreciation and Cost Segregation
Bonus depreciation allows you to deduct a large percentage of the cost of qualifying assets in the year they are placed in service. As of 2026, the bonus depreciation rate is 20% (down from 100% in 2022, phasing down by 20% each year). Even at the reduced rate, combining bonus depreciation with cost segregation still produces substantial first-year deductions.
For properties purchased in prior years when the bonus depreciation rate was higher, a lookback study can capture those higher rates retroactively.
How AE Tax Advisors Handles Cost Segregation
Our cost segregation studies are IRS-compliant, engineering-based, and audit-ready. We handle the entire process in-house — from document collection and property analysis to the final report and implementation on your tax return. Our studies typically take less than two weeks to complete.
Every study includes a detailed breakdown of reclassified components, depreciation schedules for each asset class, and the projected tax savings. We also handle the Form 3115 filing for lookback studies.
Get a Free Cost Segregation Estimate
If you own rental or commercial property and want to know how much you could save with a cost segregation study, we offer a free preliminary estimate. We will review your property details and give you a projection of potential savings before you commit to anything.
Get your free cost segregation estimate from AE Tax Advisors today.
For more information, refer to the IRS Cost Segregation Audit Techniques Guide.