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Yes, office buildings are strong candidates for cost segregation. Office parks, mid-rises, professional offices, flex space, medical suites and owner-occupied headquarters all carry parking lots, site lighting, landscaping, data cabling, dedicated circuits, server room cooling, millwork, removable flooring and tenant build-out items that can be examined as 5-year, 7-year and 15-year property instead of sitting on 39 years. With 100 percent bonus depreciation restored for qualifying property acquired and placed in service after January 19, 2025, those assets can generally be deducted in the first year. The catch is the one that applies to most rental real estate: the deduction only helps if you can use it.
Jen is a physician-turned-investor in Manchester, New Hampshire. In March 2025 she bought a multi-tenant suburban office building on the south side of town for $3,000,000, and her CPA did what the default rule says: everything except land goes on 39 years. With 15 percent allocated to land, her depreciable basis was $2,550,000, and the default schedule produces roughly $65,000 of depreciation a year. That schedule treats her parking lot, the fiber backbone, a conference room credenza and the structural steel frame as if they all wear out at the same speed. The tax code does not require her to pretend that they do. Jen is illustrative; the rules and the arithmetic below are real.
A fully engineered and accounted cost segregation study separates the cost into its components and assigns each to the correct recovery class. The IRS describes the method in its own Cost Segregation Audit Techniques Guide.
Office buildings are good candidates for three reasons. They are built around people and technology, so a lot of cost sits in items that serve the tenant's activity rather than the structure: cabling, dedicated power, specialty cooling, millwork and finishes. They churn, so every tenant cycle adds build-out components that can be classified separately. And they usually come with large parking fields, lighting, drainage and landscaping, which is 15-year land improvement property rather than part of the building.
5-year and 7-year property. Tangible personal property that stands apart from the structure and serves a specific business use: dedicated electrical and data circuits, telecom and low-voltage cabling serving tenant equipment, demountable partitions, specialty millwork and cabinetry, decorative lighting, removable floor coverings, window treatments, break room fixtures serving appliances, and supplemental cooling for server rooms. In the code these are Section 1245 property.
15-year property. Land improvements: parking lots, paving, curbing, striping, sidewalks, site lighting, fencing, signage, landscaping, irrigation and certain site utilities and drainage. Separately, qualified improvement property, discussed below, is also a 15-year class. Both are eligible for bonus.
39-year property. The foundation, framing, exterior walls, roof structure, general-purpose HVAC, general plumbing and electrical, and elevators. A quality study leaves these where they belong.
Land. Never depreciable, so the allocation between land and building matters; see our post on land value allocation.
The classification is guided by the factors from Whiteco Industries v. Commissioner, 65 T.C. 664 (1975), and the Tax Court's decision in Hospital Corporation of America v. Commissioner, 109 T.C. 21 (1997).
Site work. Paving, curbs, wheel stops, striping, pole lighting, sidewalks, fencing, freestanding retaining walls, landscaping, irrigation, monument signs and certain storm drainage. On a suburban building with a large lot, this bucket alone can be a large share of the reclassified total.
Technology infrastructure. Data and telecom cabling that serves tenant equipment rather than the building, dedicated circuits and panels for specific equipment, UPS connections and supplemental HVAC for server rooms. General building electrical and HVAC stay at 39 years, and the study carves out only what is truly dedicated to tenant or equipment use.
Interior finishes and tenant build-out. Millwork, built-in cabinetry, reception desks, conference room built-ins, break room plumbing serving appliances, decorative lighting, removable carpet and demountable partitions are examined for 5-year or 7-year treatment. Landlord-funded interior improvements to an existing building may be qualified improvement property at 15 years instead.
Indirect costs. Architecture, engineering, permits and construction management fees are allocated across the components they relate to, which is why they follow the assets into shorter classes. A study that ignores indirect costs leaves money on the table.
Bonus depreciation was 100 percent for property acquired and placed in service after September 27, 2017 and placed in service through 2022. For property acquired before January 20, 2025, the rate is set by the year placed in service: 80 percent for 2023, 60 percent for 2024, and 40 percent for a 2025 placement. The One Big Beautiful Bill Act, signed July 4, 2025, restored 100 percent bonus permanently for qualifying property acquired and placed in service after January 19, 2025; property acquired earlier, including under a binding contract signed before January 20, 2025, stays at the prior rate. Our guide to 100 percent bonus depreciation under the One Big Beautiful Bill Act explains the details. Bonus is automatic; the election is to opt out, by class. It changes timing only, and the value of the deferral depends on your rate, your hold and how you reinvest the cash.
The examples are hypothetical, rounded, and shown at a 37 percent federal rate for illustration only.
Back to Jen's building in Manchester: $3,000,000 in March 2025, ready and available for tenants the same month. The appraisal and county records support allocating 15 percent, $450,000, to land, leaving a depreciable basis of $2,550,000.
Without a study, the entire $2,550,000 is depreciated over 39 years. The IRS mid-month table rate for March is 2.033 percent, so the first-year deduction is $51,842, and later years run about $65,400.
With an engineered study, 28 percent of basis, $714,000, is reclassified: about $224,000 of 5-year property (dedicated electrical and data infrastructure, millwork, specialty finishes) and about $490,000 of 15-year land improvements (paving, lighting, sidewalks, landscaping). With 100 percent bonus, the $714,000 is deducted in year one, with no proration. The remaining $1,836,000 stays at 39 years and produces $37,326 in the first year at the March rate. Total first-year depreciation is $751,326 against $51,842 without the study, or $699,484 more.
Jen and her husband file jointly. The building earns about $180,000 before depreciation, so the study turns that into a rental loss of about $571,300, under the Section 461(l) cap of $626,000 for joint filers in 2025 ($313,000 single, adjusted annually). If Jen can use the deduction at 37 percent, the first-year tax effect of the additional $699,484 is about $258,800. If she cannot use it this year because of the passive loss rules, it carries forward, and the passive loss section below covers that question.
Carol owns an accounting practice in Nashua and buys a $2,000,000 office building in May 2025 that her firm occupies entirely from June 2025. After allocating $240,000 to land, the depreciable basis is $1,760,000. A study reclassifies 25 percent, $440,000, into 5-, 7- and 15-year property: server and network infrastructure, built-in cabinetry, a secure records room, parking and site lighting.
Because her firm uses the building in its own business, the depreciation is a business deduction rather than a rental loss, so the passive activity rules are not the constraint. With 100 percent bonus, the $440,000 is deducted in year one, and the $1,320,000 that stays at 39 years takes $18,361 at the June table rate of 1.391 percent. Her practice earns well more than the deduction, so it offsets business income and the excess business loss limit does not come into play. At 37 percent, the additional first-year savings on the $440,000 are about $162,800. Her CPA would also model the interaction with the qualified business income deduction. If the building is held in a separate entity and leased to the practice, different rules apply; our post on the self-rental trap explains why.
Ed bought an office building in June 2021 for $5,000,000 and has depreciated it over 39 years ever since. After allocating 20 percent to land, his depreciable basis is $4,000,000. A look-back study in 2026 reclassifies 24 percent, $960,000, into shorter-lived property.
Because Ed acquired and placed the building in service in 2021, when bonus was 100 percent, the reclassified property would have been fully deductible in 2021 had the study been done then. Under the 39-year schedule he has actually deducted $111,814 on those components through the end of 2025: $13,354 in 2021 at the June table rate of 1.391 percent, then $24,615 a year for 2022 through 2025. The difference, $848,186, is a Section 481(a) adjustment he claims on his 2026 return by filing Form 3115 with it, with no amended returns. Cost Seg America prepares the Section 481(a) computation and, for a separate fee, the Form 3115 itself; his CPA files it. See our guide to catching up missed depreciation with Form 3115.
The cap applies in the year the loss lands. Ed and his wife file jointly, and the building earns about $300,000 before depreciation, so the catch-up alone turns 2026 into a loss of roughly $548,000 on the building before the regular 2026 depreciation. The Section 461(l) cap for 2026 is $512,000 for joint filers ($256,000 single, adjusted annually), so about $36,000 of that loss carries forward as a net operating loss instead of landing in 2026.
Office buildings are renovated constantly, which is why QIP matters. It is an improvement made by the taxpayer to the interior of an existing nonresidential building after the building was first placed in service, excluding enlargements, elevators and escalators, and the internal structural framework. It has a 15-year recovery period and is eligible for bonus. For a landlord, that covers interior build-outs funded for a new tenant: partitions, ceilings, lighting, flooring and finishes inside the existing shell. A tenant's own improvements to a leased office can qualify the same way. The study separates QIP from 5- and 7-year personal property and from structural components that qualify for neither.
When a tenant leaves and the old build-out is demolished, a partial asset disposition election writes off the remaining basis of the removed components. Our guides on tenant improvements and partial asset dispositions cover these.
Section 179 lets certain taxpayers expense qualifying property, with a $2.5 million limit and a phase-out beginning at $4 million of purchases for tax years beginning after December 31, 2024, indexed afterward. It reaches roofs, HVAC, fire protection and alarm systems, and security systems installed after the building was first placed in service. It carries a taxable income limit tied to active business income and restrictions for noncorporate lessors, so it is less flexible for passive owners than bonus and more useful for owner-occupants. Your CPA decides how Section 179, bonus and the study work together.
For most office investors, rental income is passive. Under Section 469, passive losses offset only passive income, and the rest is suspended and carried forward. A large study deduction can therefore produce a paper loss that sits unused unless one of three paths applies. You can offset other passive income from profitable rentals or limited partnership interests. The $25,000 allowance for individuals who actively participate phases out between $100,000 and $150,000 of modified adjusted gross income, so it is unavailable to most office investors. Or you qualify as a real estate professional: more than 750 hours and more than half of your personal services in real property trades or businesses in which you materially participate, with spouses unable to combine hours for that test, and then material participation in the rental activity itself or an aggregation election covering it.
See our guides on real estate professional status and cost segregation. Even a nonpassive loss still faces basis, at-risk and the excess business loss limitation, with disallowed amounts carried forward. Project the usable portion of the deduction before you order a study.
When you sell, gain on Section 1245 personal property is recaptured as ordinary income up to the depreciation claimed. Land improvements and the building are Section 1250 property: straight-line depreciation on real property comes back as unrecaptured Section 1250 gain at a maximum 25 percent rate, and depreciation above straight-line, which includes bonus on 15-year property, is ordinary recapture. Net investment income tax may also apply.
That is rarely a reason to skip the study. A deduction taken today and reinvested usually outweighs recapture taxed years later, a Section 1031 exchange defers the gain, and a step-up at death can eliminate it for heirs. Our guide on depreciation recapture after a cost segregation study goes further.
If you bought, built or renovated an office building in a prior year without a study, Form 3115 filed with the return for the year of change takes the cumulative catch-up that year as a Section 481(a) adjustment. You must still hold the building, and the bonus percentage depends on the original placed-in-service date, never the date of the study.
The IRS Cost Segregation Audit Techniques Guide describes six common approaches. A fully engineered and accounted study works under the first two: detailed engineering from actual cost records, or engineering with documented estimates reconciled to actual cost. On an office building that means the tenant build-out, the dedicated circuits, the data cabling and the parking field are each identified from drawings, invoices and a proper inspection by an in-house analyst, a live video walkthrough, or a guided photo and video checklist the team reviews frame by frame. Each component is costed, with indirect costs allocated to it, and assigned to its recovery period with the authority that supports the call. The result is a component schedule your CPA imports and an examiner can trace line by line, signed by credentialed professionals, and defended for as long as you own the building. The estimated study gives your CPA a percentage, and a percentage cannot tell an examiner which circuits serve the tenant's equipment and which serve the building.
A six-figure first-year deduction does not wipe out salary or business income for most office investors unless they qualify as real estate professionals or have passive income. Confirm usability first.
Ownership of tenant improvements depends on the lease, who paid and who may remove them at the end of the term. Share the leases and any allowance details with your CPA and study provider.
A low land allocation invites scrutiny and a high one shrinks every deduction. Support it with an appraisal, a county assessment ratio or another reasonable method.
The 100 percent rate needs both acquisition and placement in service after January 19, 2025, and the placed-in-service date is when the building is ready and available for its intended use, which is often not the closing. Confirm both dates before you assume the rate.
Capitalizing a repair and deducting an improvement are both errors. The study and your CPA should look at the work with the tangible property regulations in mind.
If the depreciable basis after land is under $180,000, the fee eats the benefit. If you expect to sell within a couple of years with no exchange planned, recapture can outweigh the time value of the deduction. If the loss will sit suspended for years because you have no passive income and no path to nonpassive treatment, the cash benefit arrives late. Entity structure can also get in the way. We tell owners when the numbers do not work.
Suburban office parks and single-story buildings sit on large lots, so land improvements are often the biggest contributor. Downtown and mid-rise buildings usually have structured or off-site parking, so the opportunity comes from tenant build-out, specialty electrical and data infrastructure, and ongoing QIP. Flex and office-warehouse properties blend office finish with dock equipment, specialty electrical and yard improvements. Medical and dental offices run higher because of treatment room plumbing and equipment-related infrastructure. Owner-occupied headquarters combine strong documentation, especially if you built the space, with simpler usability. Office condominiums are analyzed on the interior build-out and your share of the common site improvements.
Yes. Office buildings commonly contain land improvements, tenant build-out and technology infrastructure that can be examined as 5-, 7- or 15-year property. The amount varies by building, so a property-specific study is the only reliable way to know.
Most office buildings land within 20 to 35 percent of depreciable basis, which is $200,000 to $450,000 per $1 million of depreciable basis. Heavily improved or technology-intensive buildings sit higher; simple shells sit lower.
Only if you can use the loss under the passive activity rules, basis and at-risk limits, and the excess business loss limitation. Jen's $571,300 loss reaches her joint return only if she or her husband qualifies as a real estate professional and materially participates; real estate professionals who do generally can use it. Owner-occupants who use the building in their own business are not subject to the passive rules on that use. Other investors carry the loss forward.
Yes. A look-back study with Form 3115 takes the missed depreciation as a Section 481(a) adjustment on the current return, at the bonus rate that applied when the building was placed in service, with no amended returns.
With a valid partial asset disposition election, you may write off the remaining undepreciated basis of the removed components in the year of removal. Your CPA should confirm the election is available and worthwhile.
Depreciation on personal property is recaptured as ordinary income up to the amount claimed, and real property follows the Section 1250 rules, with a maximum 25 percent rate on unrecaptured Section 1250 gain. A 1031 exchange defers the gain, and a step-up at death can eliminate it. Model your exit before you commit.
Gather your closing statement, any appraisal, your leases or rent roll, and any construction or renovation records, and loop in your CPA. Then send them to Jim Dougherty and his team at Cost Seg America. You will have a free proposal within 24 hours showing the likely reclassification and the first-year number for your building, the two figures Jen compared against her fee before she ordered, and we will say so plainly if the numbers do not work. Call 1-888-365-5023 or email info@costsegamerica.com.
This article is for general educational purposes and does not constitute tax, legal, or accounting advice. Tax law changes frequently, and the application of these rules depends on your specific facts. Consult a qualified tax professional before making decisions based on this information.
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