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IRS Rules, Form 3115 & Compliance

Reading the IRS Cost Segregation Audit Techniques Guide as an owner

The Service published the criteria. Knowing them tells you whether your study is any good.

Deprecio 3 January 2026 4 min read

Why it exists

After the courts confirmed that property qualifying as tangible personal property under the investment tax credit rules keeps that character for depreciation, the Service chose to publish a standard rather than litigate building by building.

The result is a manual describing what examiners look for. It is public, and reading it is the single most useful hour an owner considering a study can spend.

The thirteen elements

The guide describes the characteristics of a quality study: preparer expertise in construction and engineering; a stated methodology; an appropriate costing method; reconciliation of total costed to capitalised basis; explanation of the legal basis for each classification; documentation of a site inspection; a complete asset listing by recovery period; allocation of indirect costs; identification of 1245 versus 1250 property; treatment of land and non-depreciable costs; documented placed-in-service dates; consideration of the tangible property regulations; and a report a third party can follow without calling the author.

Ask any firm quoting you a study whether their report addresses all thirteen. The answer tells you a great deal.

The costing methodologies, ranked

The guide discusses several approaches and is candid about their relative reliability: detailed engineering cost estimates from actual records at the top, detailed engineering estimates from cost data next, then survey or letter methods, residual estimation and sampling approaches, and rule-of-thumb allocations at the bottom.

A report that will not name its methodology is telling you which end it sits at.

Industry-specific guidance

The guide includes chapters addressing particular property types — casinos, restaurants, retail, biotechnology, pharmaceutical, auto dealerships — describing components the Service expects to see treated a particular way in each.

Where an examiner has specific expectations for your property type, a study that ignores them is inviting a question.

What it does not say

It does not set acceptable reclassification percentages. There is no threshold above which a study is automatically challenged. What matters is whether the classifications are supported by evidence and reasoning appropriate to the building.

How to use it

Read it before you engage a firm. Ask how their report maps to it. Then read the methodology section of the report you receive and check that it does what it says. That is genuine due diligence, and it takes an afternoon.

Where this stops. This article is general information, not tax advice, and it cannot account for your basis, your entity, your participation or your state. A free feasibility review takes twenty minutes and gives you an answer specific to your property.

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The study is one piece. We can handle the rest of the return.

Deprecio is part of the Shurek Accounting & Tax family of brands. If you want the study and the tax work under one roof — the return, the Form 3115, entity structure, quarterly estimates, multi-state filings — that is a single engagement, not a hand-off between two firms.

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Find out what your building is hiding.

A feasibility review is free and takes about twenty minutes. Bring the closing statement and the depreciation schedule; we will tell you plainly whether a study pays for itself.

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