Our expertise · Engineering-Based Cost Segregation

Office Buildings Cost Segregation

Separate today's asset record from decades of tenant build-outs, and know whose basis each dollar belongs in.

An office building carries its history in its walls: several generations of tenant build-outs, partitions moved and moved again, technology infrastructure layered over older systems, and common areas refreshed on a different cycle from the suites. A useful study separates the current asset record from those historical improvements and evaluates what each component actually serves — and whether it belongs in the landlord's depreciable basis at all. With 100% bonus depreciation permanently restored under federal legislation enacted in July 2025, the timing of those classifications matters more than it has in years. Green Summit develops engineering-based cost segregation studies for office buildings, tracing tenant improvements, finishes, infrastructure and site work to the leases, allowances and records behind them.

Founders' cost segregation experience since 2001
Licensed engineers and in-house CPAs
Founded 2014
Audit-ready documentation

Who this is for

Owners, investors and operators of office buildings, single-tenant or multi-tenant, acquired, built or repositioned, and the accounting firms that advise them.

Building Owners, Investors & Operators Accounting & Advisory Firms

What we do

Assess the actual asset. We review tenant improvements, interior finishes, technology infrastructure, common areas and site improvements, and we keep the list of review candidates separate from any conclusion about their recovery period.
Develop supportable costs. We start from the acquisition and construction records you have, add documented estimating methods where the records stop and reconcile the analysis to the relevant basis.
Coordinate the investment context. We work with your tax advisor on ownership, utilization, hold period, disposition and state-treatment considerations, including the leases, construction allowances and ownership records that determine whose basis an improvement belongs in.
Support your tax team. We explain the technical basis for each classification and answer your advisor's questions, during the engagement and if the IRS asks later.

Our process

Screen the property. We review the building, the tax-owner context and the records available before we define the study, including the build-out chronology across the suites.
Review the components. We examine installed components, functional use and cost evidence, and we distinguish landlord-owned improvements from tenant-owned ones before anything enters the schedule.
Deliver and support. We deliver the engineering study and walk your tax advisor through the basis for each classification.

What you receive

An engineering-based report with asset schedules and a cost reconciliation for the property in the study. The supporting analysis addresses tenant fit-outs, common areas, building systems and site improvements, and it identifies every assumption and limitation so your tax advisor can determine usability, elections, accounting-method changes and the final return position.

Benefits

Property-specific analysis rather than a standard reclassification percentage.
A clearer asset and cost record for the owner's advisors, reconciled with the acquisition basis and the existing depreciation schedules.
Potential timing benefits evaluated in the context of your actual tax and investment position. We never present a deduction as a guaranteed cash return.

Why Green Summit

Most tax incentive studies are written by accountants. Ours are written by engineers and reviewed by CPAs. Green Summit's founders bring individual cost segregation experience dating to 2001 and 2007, respectively — professional experience that predates the firm's founding in 2014 — and that background shapes how we connect construction knowledge, engineering analysis, cost development and a reconciled record on every office study.

As a consulting partner that combines a licensed engineering firm with in-house tax professionals, we read a build-out the way the contractor who installed it would, and we build every study to be audit-ready from day one.

Frequently asked questions

What is a cost segregation study for an office building?

An engineering-based analysis that separates the cost of the building into its components and assigns each to the depreciation class the tax rules allow, so qualifying items recover over 5, 7 or 15 years rather than the building's 39-year life. In an office building the work centers on tenant fit-outs, interior finishes, technology infrastructure, common areas and site improvements, and on separating the current asset record from historical build-outs. Your tax advisor determines how the result is used.

How do you avoid including tenant-owned improvements?

We review leases, construction allowances, invoices and ownership records before anything enters the schedule. The analysis never assumes that every installed component belongs in the landlord's depreciable basis.

Can older build-outs create disposition questions?

Potentially. Retired or replaced components may warrant a separate review with your tax advisor. The study distinguishes the classification of new assets from the treatment of removed property, so the two questions stay separate and each rests on its own record.

Are partitions and raised floors always short-life assets?

No. We evaluate installation, function, permanence and the relevant tax treatment for the specific asset. The property-specific evidence matters more than the component's name.

What information should we provide?

Tenant and owner cost records, the build-out chronology, a review of mixed-use systems and a reconciliation with the acquisition basis and existing depreciation schedules. Purchase or construction costs, prior depreciation records, plans and improvement history help us establish the scope.

Will the study permanently eliminate tax or increase property NOI?

No. Cost segregation generally changes the timing of depreciation deductions, not the total. Tax utilization, basis and disposition effects require your advisor's review, and depreciation itself does not reduce the property's operating expenses or automatically improve operating NOI or lender-defined debt coverage.

Let's talk about what a study could uncover in your office building.

Tell us the building and where it is, how many tenants it holds, whether it was acquired, built or repositioned, and roughly when.

Program and technical references

IRS: Cost Segregation Audit Technique Guide

Program information reviewed September 22, 2026. Current applicability, qualifications and program terms are confirmed for each engagement.

Or call 321-273-2200 · inquiry@greensummit.com