Cost segregation is an engineering-based tax study that breaks a building’s purchase or construction cost into components with shorter depreciation lives. Instead of depreciating everything over 27.5 or 39 years, qualifying items — flooring, fixtures, site improvements, specialty electrical — are reclassified into 5-, 7-, or 15-year property, accelerating deductions into the early years of ownership.
How it works
Commercial real estate defaults to 39-year straight-line depreciation (27.5 years for residential rentals), treating the entire structure as one asset. A cost segregation study, performed by engineers working with tax specialists, walks the property and its cost records to identify everything that is legally personal property or land improvement rather than structural building: carpeting, cabinetry, dedicated electrical and plumbing serving equipment, parking lots, landscaping, signage. Depending on property type, studies commonly reclassify a meaningful share of a building’s cost basis — often in the range of 20–40% — into those shorter-lived categories.
The acceleration matters because of the time value of money and, currently, because of bonus depreciation. Property with a recovery period of 20 years or less is bonus-eligible, and with 100% bonus depreciation permanently restored for property acquired and placed in service after January 19, 2025, everything a study reclassifies into 5-, 7-, or 15-year buckets can generally be deducted in full, in year one. That combination — study plus bonus — is why cost segregation moved from a large-property nicety to standard practice across commercial real estate, and why it features prominently in the tax profile of many Delaware Statutory Trust and private real estate offerings, where accelerated depreciation often shelters much of the early-year cash distributions.
Studies aren’t only for new purchases. A look-back study on a property owned for years can capture missed depreciation all at once in the current year through an accounting-method change (Form 3115), without amending prior returns.
The trade-offs
Accelerated is not additional: total depreciation over the holding period is unchanged, so cost segregation front-loads deductions rather than creating them. Several consequences follow. Reclassified 5- and 7-year property is Section 1245 property, and on sale its depreciation is recaptured at ordinary income rates — a harsher result than the up-to-25% rate on straight-line building depreciation (see depreciation recapture). Short holding periods can therefore erode the benefit; the strategy fits owners with longer horizons, or those planning a 1031 exchange, which can carry the deferred liability forward.
Usability is the other constraint. For individual investors, the passive activity loss rules generally trap real estate losses against passive income only — large paper losses from a study may sit suspended unless the investor has passive income to absorb them or qualifies for exceptions such as real estate professional status. This is squarely advisor-and-CPA territory: the same study produces very different outcomes for different taxpayers.
Cost matters less than it once did: study fees typically run from a few thousand dollars for smaller residential properties to five figures for complex commercial assets, and are usually small relative to the present-value benefit on properties above roughly $1 million in basis.
FAQ
What is a cost segregation study in real estate?
A detailed engineering analysis that divides a property’s cost between the structure (long depreciation life) and components that qualify as personal property or land improvements (5-, 7-, or 15-year lives), so more depreciation lands in the early years.
How much does a cost segregation study cost?
Commonly a few thousand dollars for straightforward residential properties and $10,000–$25,000+ for larger or complex commercial assets, varying with property type, size, and documentation quality. The fee is generally deductible.
Is cost segregation worth it?
Usually yes for income-producing property with sufficient basis and a multi-year hold, particularly with 100% bonus depreciation available — but the answer depends on the owner’s ability to use the losses, exit timing, and recapture exposure. It’s a modeling exercise, not a reflex.
Can I do my own cost segregation study?
The IRS’s audit guide expects studies grounded in engineering methodology and documentation. DIY or purely software-based allocations exist for small properties, but quality of support is what survives an exam — most owners of substantial properties use qualified providers.
Related terms
Bonus Depreciation · Depreciation Recapture · Passive Activity Loss Rules · 1031 Exchange · Delaware Statutory Trust (DST)
Educational content only; not investment, tax, or legal advice. Consult qualified professionals regarding your specific circumstances.
