Cost Segregation Studies: Accelerating Depreciation on Commercial Property
A cost segregation study is an engineering-based analysis that reclassifies components of a commercial building from the default 39-year depreciation life (or 27.5-year for residential rental) to shorter lives: 5-year, 7-year, or 15-year property. The reclassified components, which include items like flooring, certain electrical systems, plumbing related to specific equipment, parking lots, landscaping, and decorative finishes, become eligible for bonus depreciation (100% in Year 1 under current law) or accelerated MACRS depreciation. A typical cost segregation study reclassifies 20-40% of a building’s cost, creating a front-loaded depreciation deduction that can save tens or hundreds of thousands of dollars in taxes in the year the building is placed in service or acquired.
Cost segregation study basics:
What it does:
- A commercial building is ordinarily depreciated over 39 years (straight-line)
- A cost segregation study identifies building components that qualify for shorter depreciation lives:
- 5-year property: carpet, decorative lighting, certain electrical (dedicated to movable equipment), specialty plumbing, decorative millwork, removable partitions
- 7-year property: certain furniture, fixtures, and equipment permanently attached
- 15-year property: land improvements (parking lots, sidewalks, landscaping, fencing, exterior lighting, signage, drainage)
- Qualified improvement property (QIP): interior improvements to non-residential property (15-year, bonus eligible)
- These shorter-life components are eligible for bonus depreciation; the 5- and 7-year personal property (and QIP, by election) can also take Section 179, but 15-year land improvements are not on the Section 179 list
How much gets reclassified:
- Typical reclassification: 20-40% of building cost
- Office buildings: 15-25%
- Retail/restaurant: 25-40%
- Manufacturing/warehouse: 25-35%
- Hotels/motels: 30-45%
- Auto dealerships: 25-40%
- Self-storage: 25-40%
Cost of the study:
- Small properties ($500K-$2M): $5,000-$10,000
- Medium properties ($2M-$10M): $10,000-$25,000
- Large properties ($10M+): $15,000-$50,000+
- The study cost is deductible as a business expense
- ROI is typically 5:1 to 20:1 (tax savings / study cost)
Who should get one:
- Any business that owns (not leases) commercial real property worth $500,000+
- The study is cost-effective even for properties placed in service in prior years (a “look-back” study, using Form 3115 to catch up on the missed depreciation in one year)
- The more the building cost, the higher the ROI
Who performs it:
- An engineering firm or CPA firm with cost segregation specialists
- The IRS requires a “detailed engineering analysis” (not just a desktop estimate)
- The IRS published the Cost Segregation Audit Techniques Guide (2022), which is the standard for what the IRS expects
Limitations and risks:
- Depreciation recapture at sale: reclassified personal property is subject to ordinary income recapture under IRC 1245
- 15-year property recapture: Section 1250 property, capital gain with potential 25% rate on unrecaptured Section 1250 gain
- If the property is sold within a few years, the recapture reduces or eliminates the benefit
- The study must be “reasonable in detail” to survive IRS examination
How does cost segregation work in practice?
Section 179 or bonus for a manufacturer’s building parts?
For the reclassified parts of the building, bonus is the main tool. It applies at 100% to components acquired after January 19, 2025 with a recovery period of 20 years or less. Section 179 is capped and narrower. On a building it reaches the section 1245 components and, by election, only qualified improvement property, roofs, HVAC, fire protection and alarm systems, and security systems.
The cap matters for a manufacturer that also buys production equipment that year. For 2025 the Section 179 limit is $2,500,000, reduced dollar for dollar once more than $4,000,000 of 179 property goes into service. For 2026 the figures are $2,560,000 and $4,090,000. Bonus has no dollar limit, and it works on used machinery too, if you didn’t use it before and bought it from an unrelated seller.
Can a manufacturer expense the building it buys?
Possibly, under the qualified production property rule. It’s an elective 100% write-off for the part of a US nonresidential building you use as an integral part of manufacturing, production or refining, placed in service after July 4, 2025 and before January 1, 2031. A building you buy can qualify even if it was built years ago.
For a purchase, you must acquire it after January 19, 2025 and before January 1, 2029, no one can have used it in a qualified production activity from January 1, 2021 to May 12, 2025, you can’t have used it before, and the purchase has to meet the Section 179 rules, so no related-party or carryover-basis deals. A new building instead needs its original use to begin with you and construction starting in that same window.
Only the production space counts. Offices, administrative, lodging, parking, sales and research space are left out, and so is space you own but lease to someone else. Whatever doesn’t qualify stays on 39-year straight line with the mid-month convention, with no Section 179 or bonus on the structure, and cost segregation still moves components into the 5-, 7- and 15-year classes. If that space stops being used in production within 10 years of going into service, the write-off is generally recaptured as ordinary income. California doesn’t follow this rule for personal income tax filers.
When does a cost segregation study pay for itself?
A cost segregation study typically pays for itself when the building’s purchase price or construction cost exceeds $1 million, though properties with heavy tenant improvements or specialized systems can benefit at lower values. The study reclassifies building components from 39-year (commercial) or 27.5-year (residential) property into 5, 7, or 15-year categories, accelerating depreciation deductions. Common reclassified items include carpeting and floor coverings (5-year), decorative lighting and millwork (7-year), site improvements like parking lots and landscaping (15-year), and specialized electrical and plumbing serving specific equipment. The tax savings from a cost segregation study depend on the bonus depreciation percentage in effect, your marginal tax rate, and the percentage of building costs that can be reclassified, which typically ranges from 15% to 40% of total building cost.
Start with a Diagnostic: a CPA licensed in the US and Canada reads your file and tells you in writing what's wrong and how to fix it, three to four business days after you finish the questions. The report is $250. If you hire us for any work after that, you get the $250 back as a discount on that work. Or send us your return or your letter and get a fixed price, free.
One or two plain-English guides a week on US-Canada tax. No spam, unsubscribe anytime.
Done. The next guide will land in your inbox.
Yarik Yarosh, CPA. "Cost Segregation Studies: Accelerating Depreciation on Commercial Property." Blue Cloud CPA, September 5, 2026, updated September 23, 2026. https://bluecloudcpa.com/guides/small-business-cost-segregation-study-tax-savings
This guide is general information, not tax advice for your specific situation. Which points apply, and how, depends on your facts.