Will a cost segregation study raise my audit risk, and what should I require before filing?

No one can reliably tell you that ordering a cost segregation study raises, lowers, or leaves unchanged your odds of IRS examination. The IRS does not publish a study-specific audit-selection rate. What you can control before filing is whether the accelerated depreciation has a property-specific report, supported asset classifications, a complete cost-basis tie-out, and a correct tax-return implementation.

If you are comparing study proposals or already have a draft report, AE can review the report alongside your closing records, fixed-asset ledger, and return before the deduction is claimed. Bring the actual proposal or report—not just a promised first-year deduction—to the review.

Separate audit selection from an audit-ready deduction

The IRS explanation of audit selection describes random selection/computer screening and related examinations; it does not say that filing a cost segregation study automatically triggers an audit. The study is generally a supporting workpaper, not an attachment that gives a return an “audit-proof” label. We cannot infer an individual taxpayer's selection probability or promise that a quality report will end an examination quickly.

The IRS's 2025 Cost Segregation Audit Techniques Guide (ATG) tells examiners how to evaluate a study when the issue is examined. It asks for a report that describes the property and method, explains the class life and legal rationale for each asset classification, and ties study costs to tax basis and depreciation schedules. The ATG is examination guidance, not a guarantee of IRS acceptance or a safe harbor for a percentage-based allocation.

Three checks before signing a study proposal

1. Can the provider establish the tax basis? Ask how purchase price, land, acquisition costs, seller-provided assets, prior improvements, and any existing furniture or equipment will be traced and reconciled. A report that allocates more than the supportable depreciable basis is not made defensible by detailed photographs.
2. Can it explain each material classification? Ask for asset-level descriptions, the 5-, 7-, 15-, 27.5-, or 39-year recovery class as applicable, Section 1245/1250 rationale, and cost-estimation source. The ATG flags structural components assigned improper short lives, minimal amounts left in land or building, and ambiguous asset names as issues for examiners to investigate.
3. Will the report feed a correct return? Require a schedule that the tax preparer can tie to the fixed-asset ledger and Form 4562. For a look-back study, the preparer must determine whether a Form 3115 method change and Section 481(a) adjustment are appropriate rather than assuming every late study is handled the same way. The IRS Form 3115 instructions specify depreciation-change details and support.

The ATG lists 13 principal elements of a quality study, including preparer expertise, methodology, documentation, legal analysis, unit costs, indirect-cost treatment, and reconciliation. There is no prescribed report format, and checking 13 boxes is not a substitute for correct property facts. AE's audit-ready deliverables guide shows what the finished package should contain.

Is a site visit mandatory?

The ATG recommends a field inspection for quality studies and calls it critical when drawings and construction specifications are limited, as often happens with acquired property. That is stronger than a casual optional-photo suggestion, but it is not a universal statutory site-visit requirement. Ask the provider what physical inspection, photographs, interviews, plans, invoices, and estimation sources will verify this property's components. A desktop process may have strong records for one asset and inadequate support for another; price alone does not decide the tax result.

A pre-filing example: the spreadsheet looks better than the evidence

Assume an investor buys a rental for $2 million. A draft study proposes $450,000 of shorter-life assets, but the report uses the full $2 million as its starting depreciable basis, never identifies land, and also lists furniture that the investor separately recorded in the books. That is not a question of whether $450,000 is “too large.” The immediate problems are a missing land allocation, duplicate assets, and failure to reconcile to the settlement statement and fixed-asset schedule. The owner should ask for a revised, asset-level report and tax-basis tie-out before deciding what, if anything, can be claimed.

By contrast, a large supported reclassification can still require a separate tax-benefit analysis. Bonus-depreciation eligibility depends on the property's facts and placed-in-service year; passive-activity, basis, at-risk, and other limitations can defer use of the deduction. Future sale can create recapture. The IRS depreciation publication and AE's sale-timing guide address different parts of that calculation. The study percentage alone is not the buyer's return on investment.

Bring this file to the return review

• Purchase agreement, closing statement, appraisal or other support for land value, and placed-in-service evidence.
• Construction drawings, invoices, renovation records, photographs, leases, and seller asset schedules where available.
• The full study, asset-level detail, methodology, cost sources, report assumptions, and preparer credentials.
• Prior and proposed depreciation schedules, books/fixed-asset ledger, Form 4562, and any proposed Form 3115 workpaper.
• Entity and owner returns needed to test deduction usability, plus a planned hold or sale timeline.

Failure points to catch before filing

• Promising “no audit risk” or “audit insurance.” A quality report supports the filing position; it cannot control IRS selection or guarantee the outcome.
• Accepting a round percentage without source costs. Ask how each significant amount was measured, estimated, and reconciled to actual tax basis.
• Ignoring land, structural systems, or duplicate equipment. These are specific ATG review areas, not cosmetic report details.
• Treating all shorter-life assets as automatically 100% deductible. Bonus timing, elections, placed-in-service facts, and taxpayer-level loss limits need separate review.
• Filing a late-study catch-up by assumption. Determine the correct amendment or accounting-method procedure from the prior depreciation history.

AE can compare a proposed study with the IRS ATG, identify missing support to request from the provider, and reconcile the final asset schedule to the tax return. The useful next step is a return-and-study review before the deduction is filed or, if already filed, before responding to an IRS information request. Owners with an active examination can review AE's separate cost segregation audit-defense service.

This article is for informational purposes only and does not constitute legal or tax advice. Consult a qualified tax professional regarding your specific circumstances. AE Tax Advisors, 935 Lake Elmo Dr, Suite B, Billings, MT 59105. Phone: (631) 614-5762.

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