Building Systems Decisions
Courts and the tangible property regulations treat HVAC, plumbing, electrical, elevators, and fire protection as building systems rather than as a pile of removable parts. Dedicated branches can be analyzed separately; the main system often stays with the building.
Educational information, not tax advice.
Updated 2026-10-14
Key takeaways
- For improvement testing, Treas. Reg. §1.263(a)-3 splits a building into the structure and listed systems.
- Those systems overlap the usual structural-component categories under Treas. Reg. §1.48-1(e)(2).
- Scott Paper and Morrison allocated electrical systems by function. L.L. Bean kept a rack-supported warehouse with the building. Classification and capitalization remain different questions.
- Educational information, not tax advice.
Cost segregation arguments often try to pull pieces out of HVAC, plumbing, or electrical systems. Two different rules are in play. Classification under the ITC-era regulation asks whether the item is a structural component of the building. The tangible property regulations ask which unit of property was improved. A repair-versus-capital decision about an HVAC unit does not, by itself, make the unit 5-year property.
Treas. Reg. §1.263(a)-3(e) treats a building and its structural components as one unit and then lists separate building systems — HVAC, plumbing, electrical, escalators, elevators, fire-protection and alarm, security, gas distribution, and others — as their own units for improvement testing. That list is about whether an expenditure is a capital improvement. It is consistent with, but not the same as, the structural-component list in Treas. Reg. §1.48-1(e)(2).
Scott Paper Co. v. Commissioner, 74 T.C. 137 (1980), allocated a mill’s primary electrical system by design load. Morrison, Inc. v. Commissioner, 891 F.2d 857 (11th Cir. 1990), adopted that approach for cafeteria primary electrical systems (55.9 percent on a stipulated split) and allowed kitchen panel boards that served only kitchen equipment. The same opinion kept kitchen hand sinks, sanitary wall and floor tile, garbage-room floors, and serving-line curbs with the buildings. The restaurant field discussion in the audit guide addresses kitchen HVAC that exists solely for cooking equipment. Central HVAC for occupant comfort remains a building system in those materials.
L.L. Bean, Inc. v. Commissioner, 145 F.3d 53 (1st Cir. 1998), is the integration limit. A 52-foot reserve facility used the storage-rack system as the structural support for the roof and three walls. The First Circuit held the rack system was a structural component of a building or inherently permanent structure, not section 38 property, even though racks and shelves appear in the regulation’s personal-property examples when they play no structural role. A mezzanine that supported a floor and carried lighting, sprinklers, and cable was likewise too integrated to treat as temporary furniture.
AmeriSouth applied the same building-system instinct to apartments: “special” HVAC and plumbing that served dwelling units stayed with the 27.5-year buildings. Super Intelligence, as proposed here, would keep classification and improvement testing on separate checklists. This page is educational information, not tax advice.
Do not mix the tests
Capitalizing a chiller replacement under the tangible property regulations does not assign that chiller a 5-year life. Classifying a dedicated process cooler as personal property does not decide whether a later repair of that cooler is deductible. Run each test on its own record.
Electrical allocation is not a systems-wide method
The IRS audit guide discusses functional allocation for primary and secondary electrical distribution. Do not extend that acceptance to plumbing or HVAC (flag F-09).
How to use this page
Use this page when a study is trying to pull a piece out of HVAC, plumbing, electrical, elevator, or fire-protection work. Ask first whether the question is classification (personal property versus structural component) or capitalization (did the expenditure improve a unit of property). The tangible property regulations list building systems as units for the second question. HCA and Scott Paper speak to the first.
L.L. Bean is the integration check: if the “equipment” is also the building frame, it is not personal property. Morrison is the restaurant check: kitchen panel boards that served only kitchen equipment were personal property; floors, tile, sinks, and curbs were not. AmeriSouth is the apartment check: calling HVAC or plumbing “special” did not take dwelling systems out of the 27.5-year buildings.
A proposed Super Intelligence workflow would keep those two tests on separate checklists. It is not described as operational. Educational information, not tax advice.
Limits and flags
Capitalizing work on a building system under Treas. Reg. §1.263(a)-3 does not assign that system a 5-year recovery period. Classifying a dedicated process cooler as personal property does not decide whether a later repair of that cooler is deductible. Run each test on its own record.
IRS-described acceptance of functional allocation is for primary and secondary electrical distribution (flag F-09). Do not extend that sentence to plumbing or HVAC. L.L. Bean’s rack-supported warehouse is a First Circuit integration holding, not a nationwide rule that every mezzanine is a building. AmeriSouth’s “special” apartment HVAC stayed with the 27.5-year buildings on those facts (flag F-11).
Super Intelligence is proposed only. Educational information, not tax advice.
Practice note
Write the unit of property on the worksheet before you write a class life. A chiller replacement is tested against the HVAC building system under Treas. Reg. §1.263(a)-3. Whether that chiller was already personal property is a different HCA/Scott Paper question. Mixing the two produces both over-expensing and over-classifying.
Morrison’s kitchen panel boards and L.L. Bean’s racks are the poles of the same idea: a system that exists only for equipment can be personal property; a system that is the building cannot. AmeriSouth’s “special” apartment HVAC sat in the middle and stayed with the residential buildings.
Sources
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- 7IRS Publication 5653 — Cost Segregation Audit Techniques Guide (rev. 2-2025)(opens in a new tab)
Written for IRS examiners. The guide states it is not an official pronouncement of law and cannot be cited as authority. It predates the July 2025 law.