Cost segregation for data centers

A data center is mostly electrical and mechanical plant with a roof: UPS, generators, PDUs, CRAC units, and raised floors can push reclassification past 40% of basis. The hard question is where equipment-serving systems end and building systems begin.

By The Carryforward Desk3 min read · July 7, 2026

Strip the servers out of a data center and what remains is still mostly machine: switchgear, UPS modules, batteries, generators, PDUs, chillers, CRAC units, containment, and a raised floor to knit it together. That is why data centers reclassify 35–50% of depreciable basis in a cost segregation study — and why the entire analysis compresses into one question: which systems serve the IT load, and which serve the building?

The building-systems boundary

The Cost Segregation Audit Techniques Guide classifies electrical and mechanical systems by what they primarily serve — the framework courts built in cases like Scott Paper Co. v. Commissioner, 74 T.C. 137 (1980). Applied to a data center:

Power chain. Utility service, switchgear, generators, UPS, batteries, and PDUs are allocated by load. In a purpose-built facility, IT load dominates — often upward of 80–90% of design capacity — so most of the chain classifies as 5- or 7-year Section 1245 property. The slice sized for life safety, lighting, and office load stays at 39 years, and examiners expect to see the one-line diagram and load calculations behind the split.
Cooling. CRAC/CRAH units, in-row cooling, containment, and the chilled-water plant serving heat rejection from equipment follow the equipment. Comfort HVAC for offices and NOC space is structural. Shared central plants get allocated — the contested middle ground.
Raised floors. Pedestal-and-panel access floors routing air and cable to machines are argued as personal property on movability and function grounds; a floor with any structural role is not. Documentation of removability and reuse carries the position.
Fire suppression and security. Clean-agent suppression protecting equipment rooms has been classified with the equipment; building-wide sprinklers are structural. Access control and monitoring dedicated to the data hall is 5-year property.

Recovery periods track Rev. Proc. 87-56 classes via Pub 946 — commonly 5-year for computer-adjacent equipment and 7-year for other machinery, with the shell and office at 39.

An illustrative allocation

Illustrative allocation for a $60M enterprise data center (shell plus electrical/mechanical fit-out, IT hardware excluded), land excluded:

Data center basis after cost segregation%

Illustrative; hyperscale fit-outs where the owner's basis is mostly plant run higher, mixed office/data buildings lower.

All of the short-life property is eligible for 100% bonus depreciation when acquired after January 19, 2025 — on a $60M basis, roughly $27M of year-one deduction at these illustrative percentages.

The trap: capacity is not use

The recurring exam failure is allocating the whole power chain to IT because the facility is "a data center." Generators sized with life-safety capacity, UPS feeding building controls, chillers cooling office space — every shared system needs a documented allocation, and a study that claims 100% of shared infrastructure invites the examiner to reopen everything else. The inverse trap is commercial: in powered-shell leases, owners sometimes study systems the tenant paid for and owns under the lease. Basis follows ownership; read the lease before the engineer reads the one-line diagram. Comparative context across asset types is in cost seg by property type.

Frequently asked questions

How much of a data center can cost segregation reclassify?

Frequently 35% to 50% of depreciable basis for a powered-shell-plus-fit-out, and more where the owner's basis is concentrated in the electrical and mechanical fit-out. UPS systems, batteries, PDUs, generators, switchgear serving IT load, CRAC/CRAH units, and raised access floors are the major Section 1245 candidates; the shell, office space, and building-serving systems remain 39-year property.

Are backup generators and UPS systems personal property?

Generally yes, to the extent they serve the IT load rather than the building. Generators, UPS modules, batteries, and power distribution units that exist to keep servers running classify as 5- or 7-year Section 1245 property under the primary-use analysis; capacity serving life safety and general building load is a structural component and must be carved out by load allocation.

Is a raised access floor 39-year or short-life property?

Bolt-together raised access floor systems installed to route cooling and cabling to equipment are commonly classified as personal property under the movability and function factors — they are removable, reusable, and serve the machines. The IRS has litigated adjacent questions, so the position depends on documented facts: pedestal-and-panel construction, no structural role, and equipment-serving purpose.

Who does the study in a leased data center?

Each party studies its own basis. In a powered-shell lease the landlord owns the shell and often the primary power path, while the tenant owns the fit-out — UPS, PDUs, CRACs, containment, racks. Tenant fit-out studies typically reclassify a far higher percentage than landlord shell studies, and lease terms deciding who owns improvements at termination control whose study it is.