Real Estate Tax Calc
Common short-life assets in office buildings
A standard office building is 39-year property, but a cost segregation study routinely identifies shorter-lived components. 5-year property: specialty electrical systems, data and telecom wiring, certain floor coverings, security systems, and personal property used in the operation of the building. 7-year property: furniture and fixtures the landlord owns. 15-year property: parking areas, walkways, landscaping, fencing, outdoor lighting.
Interior improvements qualifying as Qualified Improvement Property (QIP) — renovations to occupied tenant suites or common areas after the building was first placed in service — are 15-year assets eligible for bonus depreciation, regardless of when the building was built.
Specialized office types with higher yields
A plain vanilla suburban office may have 15–20% reclassifiable. Medical and dental offices often have higher proportions of short-life property because of specialized plumbing, electrical (200-amp drops for imaging equipment), cabinetry, and casework. Technology and data center buildouts can have over 30% reclassifiable given raised flooring, precision HVAC, and UPS systems.
Lab and R&D buildings are similarly rich in 5-year personal property. If you own a specialized office, make sure your cost seg engineer has experience in that property type — misclassification is common without it.
When the numbers work
On a $3M office building, a study might identify $450,000–$750,000 in 5- and 15-year property. With 40% bonus depreciation in 2025, $180K–$300K moves to year one. Study fees for an office building typically range $6,000–$20,000 depending on size and complexity. The ROI is usually favorable above $750,000 in purchase price.
For existing buildings, the same look-back opportunity applies: claim all prior years' missed depreciation in the current year via a Form 3115 change in accounting method.
Bonus depreciation in 2025 and beyond
How much of a study lands in year one depends on the bonus depreciation rate. Bonus had been phasing down (60% in 2024, 40% in 2025), but 2025 legislation restored 100% bonus depreciation for qualified property placed in service after January 19, 2025. Property placed in service earlier in 2025 uses the 40% rate, so the placed-in-service date materially affects your first-year deduction.
At 100%, the full 5-, 7-, and 15-year bucket a study identifies — including QIP renovations — is deductible in the first year. On the $3M office building above with $450K–$750K of short-life property, that is the entire amount in year one rather than the $180K–$300K a 40% rate allows.
A fuller worked example
Suppose you buy a suburban office building with a $3,000,000 depreciable basis and place it in service in mid-2025. A study reclassifies 22%, or $660,000, into 5-, 7-, and 15-year property, leaving $2,340,000 in the 39-year shell. Straight-line depreciation on the whole $3M would be roughly $77,000 in the first year.
With 100% bonus on the reclassified $660,000, first-year depreciation instead approaches $720,000. At a 37% combined marginal rate that defers about $265,000 of tax into year one. Even netting out the study fee and eventual recapture, the present value of pulling that deduction forward is significant for an owner who holds the building for several years — and larger still for a medical or lab building with a higher reclassifiable percentage.
Qualified Improvement Property in office buildings
Office space turns over and gets reconfigured constantly, which makes Qualified Improvement Property (QIP) a major opportunity. QIP is interior improvement to nonresidential real property made after the building was first placed in service — new partition walls, ceilings, flooring, interior lighting, and finishes in a tenant suite or common area. QIP is 15-year property eligible for bonus depreciation.
QIP excludes building enlargements, elevators and escalators, and the internal structural framework, but the typical office fit-out — demountable walls, carpet and LVT, drop ceilings, and lighting — usually qualifies. Rather than defaulting a $300,000 tenant improvement into the 39-year shell, classifying it as QIP shortens the recovery period by 24 years and unlocks first-year bonus depreciation.
Passive loss rules can defer the benefit
A large first-year deduction typically produces a paper loss, and for most owners rental real estate is a passive activity. Passive losses offset only passive income unless you qualify as a real estate professional and materially participate, or use the $25,000 special allowance (phasing out between $100,000 and $150,000 of modified AGI).
If you cannot use the loss now, it is suspended and carried forward until you have passive income or dispose of the building. The deduction is not wasted, but the benefit is delayed. Owners who also earn active real estate income, or who own the office through an operating business they materially participate in, are best positioned to use a large first-year loss immediately.
Recapture and audit defense
Cost segregation defers tax; it does not erase it. At sale, the 5- and 7-year personal property is subject to Section 1245 recapture as ordinary income up to the depreciation taken, while the 15-year improvements and shell fall under Section 1250, with straight-line building depreciation recaptured at up to 25%. A 1031 exchange can defer that recapture entirely.
Because office studies claim substantial first-year deductions, use an engineered study that physically inspects the property, ties each component to its MACRS class with a written rationale, and follows the IRS Cost Segregation Audit Techniques Guide. Retain the report and workpapers permanently. Specialized office types especially reward an engineer experienced in that property class, since misclassification of medical or lab systems is common.
Planning tips for office owners
Time the study to the placed-in-service year to match a high-income year, and coordinate with any tenant build-out so QIP costs are captured contemporaneously rather than reconstructed later. If you have owned the building for years without a study, a look-back study combined with a Form 3115 change in accounting method lets you claim all previously missed accelerated depreciation in the current year with no amended returns.
Given elevated office vacancy in many markets, some owners are repositioning space or converting buildings to other uses. Major reconfigurations create fresh basis and new QIP, and a conversion can change the building's recovery class entirely — both are moments to bring in a cost segregation engineer so the new investment is placed on the most favorable schedule from day one.
Components typically identified in an office study
A general office study sorts costs into recovery classes. 5-year personal property commonly includes data and telecom cabling, security and access-control systems, decorative and accent lighting, certain floor coverings such as carpet and LVT, break-room appliances, and specialty electrical serving specific equipment. 7-year property covers landlord-owned furniture and fixtures in lobbies and shared amenity areas.
15-year land improvements round out the study: parking lots and structures the owner depreciates, walkways, landscaping and irrigation, exterior and parking lighting, monument signage, and site utilities. Each component is measured, priced, and assigned to a MACRS class based on its function, which is why an on-site engineering inspection captures materially more than a desktop estimate.
Why specialized offices outperform
The reclassifiable percentage varies widely by office type. A plain suburban office may yield 15–20%, driven mostly by site improvements and basic finishes. Medical and dental offices often reach 25–35% because of specialized plumbing for exam and lab sinks, dedicated electrical drops for imaging and equipment, medical gas lines, and extensive built-in casework and cabinetry — nearly all of which is 5-year personal property.
Laboratory, R&D, and data-oriented buildouts can exceed 30% thanks to raised access flooring, precision and supplemental HVAC, uninterruptible power supplies, and process piping. If you own a specialized office, insist on an engineer with experience in that exact property class; the difference between a generic and a specialty-aware study can be several percentage points of the total basis.
When an office study does not pay
Cost segregation is not universally worthwhile. Below roughly $750,000 in basis, the study fee (typically $6,000–$20,000 for an office) can absorb too much of the benefit. If you plan to sell within a year or two, recapture reverses most of the acceleration, leaving little more than a short deferral. And if the passive activity rules prevent you from using the resulting loss, the benefit is postponed rather than realized.
The right test is a present-value comparison: the deduction accelerated times your marginal rate, discounted over your expected hold, minus the study fee and eventual recapture cost. For most office owners above the size threshold who intend to hold for several years — and especially owners of medical, lab, or data-heavy buildings — that comparison comes out clearly positive.
Frequently asked questions
Does a medical office get more from a cost seg study?
Often yes. Specialized plumbing, electrical drops, and medical cabinetry increase the proportion of 5-year personal property compared to a standard office.
What bonus depreciation rate applies to a 2025 office purchase?
It depends on the placed-in-service date. Property placed in service after January 19, 2025 qualifies for 100% bonus depreciation; property placed in service earlier in 2025 uses the 40% phase-down rate.
Are tenant improvements in an office eligible for bonus depreciation?
Landlord-owned interior improvements made after the building was placed in service are usually Qualified Improvement Property — 15-year property eligible for bonus depreciation. Tenant-funded improvements are generally the tenant's asset.
What percentage of an office building can be reclassified?
A plain suburban office is often 15–20%, while medical and dental offices reach 25–35% and lab or data-heavy buildouts can exceed 30%, because of specialized plumbing, electrical, and equipment-related components.
Is tenant improvement work included?
Only improvements the landlord owns. Tenant-paid buildouts done by and for the tenant are generally the tenant's asset to depreciate.
How does the ROI compare to other property types?
Office buildings typically fall in the middle — below industrial and medical, above plain vanilla residential. Specialized offices (medical, lab, data center) outperform standard ones significantly.
Sources
Educational information and estimates only. Not tax advice. Tax rules change and vary by situation; consult a qualified tax professional before acting.