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Cost segregation studies: what the IRS audit guide expects you to support

Reviewed 2026-09-15 · AI-assisted draft and editing; sources and limitations remain visible for independent review.

Answer: There is no license, credential, or prescribed method for a cost segregation study, and the IRS says so plainly. Its Cost Segregation Audit Technique Guide, Publication 5653 revised February 2025, states that the Service has not established requirements or standards for preparing these studies, that courts have addressed component depreciation but not study methodology, and that the guidance that exists emphasizes one thing: identifying section 1245 property is factually intensive and must be supported by corroborating evidence. What the guide does supply is the standard an examiner is told to apply. It defines a quality study by thirteen elements and a quality report by nine, it prefers substantiation from actual cost records over estimation, and it describes an initial risk analysis that begins by reading the report for methodology and property classifications. The classification question underneath is older than the guide. After Revenue Ruling 75-178 withdrew the functional or equivalency test, the test is whether an asset is inherently permanent, examined through the six Whiteco factors, and the Tax Court's decision in Hospital Corporation of America carried the investment-credit precedent forward into the modern recovery system, with the Service acquiescing in that much by Action on Decision 1999-008. This page turns that material into a checklist for commissioning, reviewing, or defending a study. It is not itself authority, and neither is the guide.

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Scope

Jurisdiction: United States — federal

Tax periods: Not period-specific; checked 2026-09-15, Guide revision date February 6, 2025

Assumptions

Exclusions

What the guide is, and what it is not

Publication 5653 carries an express disclaimer: it is not an official pronouncement of the law or the position of the Service and cannot be used, cited, or relied upon as such, and it is current only through its revision date. Treat it accordingly. It is an examiner's playbook, which makes it extremely useful for predicting what will be asked and useless as authority for an answer. Every substantive proposition a study relies on still has to trace to the Code, the regulations, or case law.

The guide is nonetheless candid about the vacuum it operates in. Chapter 3 states that the Service has not established any requirements or standards for preparing cost segregation studies, and that the older guidance it can point to consists of a revenue ruling, a technical advice memorandum, and a chief counsel advice, all emphasizing that the section 1245 determination is fact-intensive and must be supported by corroborating evidence. It adds the underlying assumption drawn from that material: that a study is performed by qualified individuals and professional firms competent in design, construction, auditing, and estimating procedures relating to building construction.

The thirteen elements a study is measured against

Chapter 4 lists them. Preparation by an individual with expertise and experience. A detailed description of the methodology. Use of appropriate documentation. Interviews conducted with appropriate parties. Use of a common nomenclature. Use of a standard numbering system. An explanation of the legal analysis. Determination of unit costs and an engineering take-off. Organization of assets into lists or groups. Reconciliation of total allocated costs to total actual costs. An explanation of the treatment of indirect costs. Identification and listing of section 1245 property. And consideration of related aspects, which the guide names as section 263A, change in accounting method, and sampling techniques.

Two of those repay close reading. On the preparer, the guide states there are no prescribed qualifications, then says a study by a construction engineer is generally more reliable than one by a person with no engineering or construction background, while adding that construction knowledge alone is not the only criterion and that cost estimating experience and knowledge of the applicable tax law matter too; a quality study identifies the preparer and references their credentials and experience. On methodology, the guide acknowledges that a real study may use a variant or combination of methods and may not even name the method used, and says a quality study always describes the methodology and details the steps taken to classify assets and determine costs. A report that will not say how it got there is the first thing an examiner notices.

The report is a separate deliverable with its own elements

Chapter 4 lists nine report elements: a summary letter or executive summary, a narrative report, a schedule of assets, a schedule of direct and indirect costs, a schedule of property units and costs, engineering procedures, a statement of assumptions and limiting conditions, a certification, and exhibits. A study can be methodologically sound and still fail the review because the report does not contain the schedules that let a reviewer test it.

Chapter 5 describes what happens next. The initial risk analysis begins with a request for the report, then a full read with emphasis on the property classifications, then a review of property units and asset types. The guide expects assets to be organized into unit groups with both a property unit summary, listing unit groups by asset class or recovery period, and a property unit detail, listing the individual assets in each group with their cost basis. It says in terms that the report should give background on the property, an explanation of the methodology, details of the assets classified, the applicable class lives and recovery periods, and the rationale and authority for the classifications made. That last item is the one most often thin.

The classification question underneath: not a bright line

Chapter 2 states there is no general bright-line test for separating section 1245 property from section 1250 property and that each situation depends on its facts. Section 1245(a)(3) defines section 1245 property by categories, beginning with personal property and other tangible property used as an integral part of manufacturing, production, extraction or certain services, and section 1250(c) defines section 1250 property residually as any real property other than section 1245 property that is or has been subject to the depreciation allowance. So the practical question is whether an item is a building or a structural component of one.

The guide traces how that question is answered. Early administrative rulings applied a functional or equivalency test, several courts rejected it, and Revenue Ruling 75-178 withdrew it, leaving classification to turn on the manner of attachment to the land or structure and how permanently the property is designed to remain in place. Whiteco Industries supplied the six factors examiners use: whether the property is capable of being moved and has in fact been moved; whether it is designed or constructed to remain permanently in place; whether circumstances show the expected or intended length of affixation; how substantial and time-consuming removal would be; how much damage removal would cause; and the manner of affixation to the land. Hospital Corporation of America then held that precedent developed under the investment credit remained applicable in determining section 1245 property under the modern recovery system, and Action on Decision 1999-008 records the Service's acquiescence on that point while noting it did not agree with the court's asset-by-asset conclusions. A study that lists the six factors without applying them to the actual assets has not done the work.

Two traps the guide flags before the study begins

The first is the purchase agreement. In Peco Foods the taxpayer bought two processing plants in applicable asset acquisitions and signed written allocation schedules with the seller, then commissioned a study and filed to change its accounting method to reclassify property. The Tax Court held the taxpayer bound by the clear and unambiguous terms of its own allocation schedules and denied the change. The guide notes it is unclear whether that holding extends beyond applicable asset acquisitions, but the planning point is unambiguous: allocation language signed at closing can foreclose a study commissioned afterwards, so the allocation should be reviewed before it is executed rather than after.

The second is the reconciliation shortcut. The guide states that applying a pro-rata step-up factor to individually estimated costs merely to reconcile to the total purchase price of the improvements and personal property is not an appropriate cost estimation methodology, and it works an example in which that step-up inflates both the section 1245 property and the land improvements. More generally, the guide says substantiation using actual costs is more accurate than estimates, and that where estimation is the only option the methodology and the source of the cost data should be clearly documented.

Check the guide's own currency before quoting its tables

Publication 5653 carries a February 2025 revision date and states that it is current only through that date. Its chapter on the first-year depreciation allowance reproduces rate tables keyed to acquisition before or after September 28, 2017, and those tables show a declining schedule for later placed-in-service years. Legislation enacted in July 2025 changed the governing percentages for property acquired after January 19, 2025, so the guide's tables should not be used as the current rate source. They remain useful for the opposite purpose: they still set out the schedule that applies to property acquired on or before that date, which is no longer in the current Code text.

The sibling page Section 179 or bonus depreciation: pinning the rule to the acquisition date deals with that fork directly. This page differs from the live page Business repairs vs. capital improvements: the §1.263(a)-3 decision sequence in what it examines. That page asks whether an expenditure is a deductible repair or a capitalized improvement. This one assumes capitalization has happened and asks whether a study reallocating that basis will survive review.

A short review sequence, and where to take it

Read the report once for methodology and once for classifications. Check that the thirteen study elements are visible in the document rather than asserted in a cover letter. Test the reconciliation of allocated costs to actual costs and look specifically for a pro-rata step-up. Pull the purchase agreement and any section 1060 allocation schedule and compare them to the study's asset descriptions. For each disputed asset, find the factor-by-factor analysis and the authority cited for it. Then list the assets where the file has a conclusion but no evidence, and treat that list as the work remaining.

For a single contested asset class, ask Taxterity a research question that states how the asset is attached and what removal would take, or have it draft a Federal Tax Memo on the inherently permanent test for that class; then confirm each authority against the Code, the regulations, and the case text before the position is signed off.

Related research

Official sources

  1. IRS Publication 5653 (2-2025), Cost Segregation Audit Technique Guide — Cover disclaimer and revision date 2-6-2025; ch. 2.K and 2.L (tests for distinguishing §§ 1245 and 1250, Rev. Rul. 75-178, Whiteco six factors); ch. 2.M (Hospital Corporation of America; AOD-1999-008)
  2. IRS Publication 5653 (2-2025), Cost Segregation Audit Technique Guide — Ch. 3.D (no Service requirements or standards; actual costs preferred; pro-rata step-up example); ch. 4.B, 4.C.1 to 4.C.13 (thirteen study elements) and 4.D.1 to 4.D.9 (nine report elements)
  3. IRS Publication 5653 (2-2025), Cost Segregation Audit Technique Guide — Ch. 5.B.1 (initial risk analysis; report contents; unit groups, property unit summary and property unit detail); ch. 6.B.4 (Peco Foods); ch. 6.H.6 (first-year allowance rate tables as of the revision date)
  4. 26 U.S.C. § 1245 — Gain from dispositions of certain depreciable property — § 1245(a)(3), definition of section 1245 property, subparagraphs (A) through (G)
  5. 26 U.S.C. § 1250 — Gain from dispositions of certain depreciable realty — § 1250(c), definition of section 1250 property as real property other than section 1245 property that is or has been subject to the depreciation allowance

Limitations