A measured reference on what the IRS actually evaluates in a cost segregation studyA study that reclassifies portions of a building’s basis into shorter-life property (5, 7, or 15-year) so it depreciates faster.. What matters in practice, where defensibilityDefensibility is the property of a study that allows it to survive examination — methodology, documentation, and consistency with the regulations. actually comes from, and where the risk patterns sit.
The audit base rate for the relevant filings is small. The question that determines the outcome is not will this get audited — it is if it does, what holds up? Methodology and documentation hold up. Brand and price are not part of the examination.
Most of the public worry about cost segregation is about the wrong variable. The thing that turns a study into a problem is rarely the existence of the study — it is the §469 posture§469 governs passive activity losses. Cost-seg losses applied against W-2 wages without material participation or REPS qualification is the most common downstream failure mode. on the return that uses it.
Engineering firms and independent providers follow the same federal guidance. The variation between competent shops is operational — turnaround, documentation format, revision behavior — rather than methodological.
For a typical residential property, two competent studies usually fall within a few percentage points of each other on reclassified basis. The buyer’s decision is being made on operational terrain, even when the marketing suggests otherwise.
A subset of providers has standardized the residential study workflow into software. The methodology is unchanged from the engineering tradition. Operational consistency tends to be higher because the steps are the same on every file.
The trade-off is straightforward. Standardization tends to lower price and improve consistency of documentation. It is less appropriate for unusual properties — large mixed-use, ground-up construction, anything where on-site engineering judgment materially changes the schedule.
Hypothetical, for illustration. Numbers rounded.
A short checklist. Answer based on what you actually have in the binder, not what was promised.