Cost segregation audit defense.

Where audit risk actually concentrates.

The public worry about cost segregation usually targets the wrong variable. The study itself rarely fails an examination. The §469 posture on the return that uses it does. So does an engineering basis built from purchase-price ratios instead of components. Below are the four patterns examiners flag, with severity. None is "cost seg generally"; each is a specific failure mode.

The 13 quality elements an examiner evaluates.

IRS Pub. 5653 (Cost Segregation Audit Techniques Guide) defines 13 quality elements an examiner formally evaluates during a cost segregation study examination. Methodology and documentation account for the bulk of the weight; provider brand and price paid are explicitly not part of the evaluation. Each row below shows what an examiner looks for and how the Cost Seg Smart deliverable addresses it.

Methodology and documentation hold up. Brand and price paid are not part of the examination — Pub. 5653 explicitly does not evaluate either. The same engineering standards apply whether you paid $495 or $15,000.

Audit defense scope varies materially across providers. For how audit defense scope varies across the 27 reviewed providers, see the cross-provider review at costsegregationreviews.com — or check the head-to-head comparison hub for Cost Seg Smart vs each named firm on audit-defense scope.

What we provide if your study is examined.

Audit support scope is committed in writing below. Same posture as engineering firms charging $5,000–$15,000 — we provide engineering documentation; your CPA, EA, or attorney provides taxpayer representation. The boundary is a Circular 230 professional-services line, not a service-tier choice.

If the IRS rejects our methodology in writing.

If the IRS formally rejects our engineering methodology in writing — not questions specific reclassifications, but rejects the underlying basis — we will revise the study at no charge. If the revised study still cannot be defended, we refund the study fee. This is rare; we have not had a study fail an IRS examination on methodology to date. The Pub. 5653 framework our reports follow has 28 years of Tax Court support starting with Hospital Corp. v. Commissioner.

What your CPA has to work with.

When an examiner questions a specific reclassification, this is the material the report already contains for that component, laid out the way an information document request (IDR) asks for it. Component, basis and citations below are illustrative. Your CPA drafts and submits the actual response; our part is that the underlying documentation is already assembled and cited, and that we will explain any of it in writing on request.

This pattern — component identification, cost-source citation, Rev. Proc. 87-56 asset class, indirect-cost methodology, Tax Court precedent, workpaper exhibits — is how every reclassification in the report is documented, not something assembled after the fact. If your CPA needs any of it explained, ask us in writing and we will; your CPA writes and submits the reply to the examiner.

Audit-defense components in every report.

The 40+ page deliverable is structured around the Pub. 5653 quality elements. Each section below is what an IRS examiner would request via an Information Document Request (IDR), already assembled in the report, so your CPA is pulling an exhibit rather than commissioning new work.

• Methodology Section — engineering basis, industry-standard construction cost data sourcing, classification rationale per asset class, geo + quality multiplier methodology, indirect-cost allocation logic. Pub. 5653 element #02.
• Data Sources & Cross-References — county assessor records, RentCast property data, OSM building enrichment, satellite imagery citations. Pub. 5653 element #04 (source documentation).
• Component Schedule with Construction Cost Basis — every component listed individually with cost basis, recovery period, asset class, and Rev. Proc. 87-56 line citation. Pub. 5653 elements #05 + #06.
• Year-by-Year Depreciation Schedule — straight-line and accelerated depreciation by class for every year through full recovery, with §168(k) bonus treatment shown explicitly per component class.
• Land Valuation Methodology — county assessor cross-reference + statistical metro/state ratio fallback. Land separated from depreciable basis with documented derivation.
• MACRS Classification with Rev. Proc. 87-56 Anchor — every component's recovery period mapped to a Rev. Proc. 87-56 asset class. Pub. 5653 element #09.
• Internal Technical Review & QC — signed statement that the methodology, classifications, and cost basis match engineering principles and the supporting workpapers. Pub. 5653 element #01.
• Form 3115 Readiness Pack (lookback studies only) — §481(a) cumulative adjustment calculation, prior-year depreciation reconciliation, automatic-consent eligibility certification under Rev. Proc. 2015-13.

See the public sample reports at costsegsmart.com/sample-report/ → for the full document structure across property types.

The two cases that define cost-seg defensibility.

Engineering-based reclassification has 28 years of Tax Court precedent. Two decisions established the core. Hospital Corp. of America validated the methodology in 1997. AmeriSouth XXXII set the documentation bar examiners now apply.

The statutes a defensible study lives under.

Five primary statutes plus two Revenue Procedures govern every defensible cost segregation study. Each is linked to its primary source. These are the citations that appear in IDR responses, in audit conferences, and in Tax Court memos.

Audit-defense questions, answered without hedge.

Sources & primary references.

Every claim on this page is grounded in the IRS primary sources and Tax Court decisions below.

• IRS Cost Segregation Audit Techniques Guide (Pub. 5653) — canonical IRS framework defining the 13 quality-control elements every defensible study must address.
• Rev. Proc. 87-56 — Asset Class Lives — assigns each asset class to its IRS recovery period (5/7/15/27.5/39 years).
• Rev. Proc. 2015-13 — Automatic Consent for Method Changes — DCN 7 (depreciation method change) is automatic-consent; no IRS pre-approval needed for lookback Form 3115 filings.
• 26 U.S.C. §168 — MACRS — governs MACRS recovery periods + §168(k) bonus depreciation; the statutory basis for cost-seg reclassification.
• 26 U.S.C. §263A — Capitalization Rules (UNICAP) — Pub. 5653 element #07: consistency with §1.263(a) capitalization regulations.
• 26 U.S.C. §481(a) — Method-Change Adjustments — statute permitting lookback catch-up depreciation via Form 3115.
• Hospital Corp. of America v. Commissioner, 109 T.C. 21 (1997) — Tax Court decision establishing engineering-based reclassification under MACRS.
• AmeriSouth XXXII, Ltd. v. Commissioner, T.C. Memo. 2012-67 — Tax Court memo setting the documentation bar examiners now apply.
• IRS Pub. 946 — How to Depreciate Property — MACRS recovery periods, conventions, and depreciation tables underlying every component classification.
• IRS Form 3115 — Application for Change in Accounting Method — mechanism for §481(a) lookback adjustments on properties already placed in service.
• Treas. Reg. §1.469-1T — material participation rules + §469(c)(7) STR exception; defines the §469 posture that must be defensible to use cost-seg losses against W-2 income.
• Circular 230 — Practice Before the IRS — defines who may represent taxpayers before the IRS; the boundary between engineering documentation and taxpayer representation.
• Cost Seg Smart 2026 Benchmarks Report (n=412) — original dataset of reclassification ratios across 13 property types; methodology benchmark.

If you're evaluating a commercial property cost segregation study, see our commercial overview → for asset-class enumeration, pricing tiers, and worked examples by property type. CPAs evaluating studies for clients: see /for-cpas/ → for partner workflow and private-label deliverables.

See sample reports →   ·   Order your study →