A cost segregation study is an engineering-based tax planning exercise that identifies components of a commercial real estate purchase or construction project that can be depreciated on shorter MACRS recovery periods than the 39-year life typically assigned to nonresidential real property. The goal is to accelerate tax deductions into the early years of ownership, which has a meaningful time-value-of-money benefit for the property owner.
A typical cost segregation study on a newly acquired commercial building can reclassify 20% to 40% of the purchase price out of 39-year property and into 5-, 7-, or 15-year buckets, producing first-year tax savings measured in tens or hundreds of thousands of dollars on a mid-size property.
The methodology is rigorous. A qualified cost segregation specialist, typically an engineering firm or a specialty tax practice, walks the property, reviews construction documents and purchase records, and assigns each component to its proper MACRS category.
Five-year property typically includes decorative lighting, certain plumbing fixtures, specialty electrical systems, and movable partitions. Fifteen-year property includes qualifying land improvements: parking lots, sidewalks, landscaping, fencing, and site lighting.
Seven-year property is less common in pure real estate but applies to certain office furniture and equipment. Anything not affirmatively reclassified stays in the 39-year bucket, so the quality of the engineering analysis directly drives the benefit.
The Tax Cuts and Jobs Act of 2017 dramatically enhanced the value of cost segregation by expanding bonus depreciation to 100% for qualifying property with recovery periods of 20 years or less, placed in service between September 27, 2017 and January 1, 2023. Bonus depreciation has been phasing down since then (80% in 2023, 60% in 2024, 40% in 2025) but remains a powerful accelerator.
The Qualified Improvement Property category, created by TCJA and clarified by subsequent legislation, qualifies most interior non-structural improvements to nonresidential real property for 15-year recovery and bonus eligibility, a meaningful benefit for tenant improvements and renovations.
Cost segregation is most often performed at the time of acquisition or completion of construction, but Section 481(a) also allows the methodology to be applied retroactively to existing holdings through an accounting method change filed on Form 3115. The catch-up adjustment (the difference between depreciation actually taken and depreciation that would have been taken under the new method) is typically claimed as a one-time deduction in the year of change, which can produce very large tax benefits for owners of long-held properties.
On the sale of a building that has been cost-segregated, some of the accelerated depreciation is subject to depreciation recapture at ordinary rates, a factor that sophisticated sellers incorporate into the hold-versus-sell analysis.