How the IRS Reviews a Cost Segregation Study: The Examination Process

The IRS Cost Segregation Audit Technique Guide is written from the examiner's perspective, including a step-by-step process for reviewing and examining cost segregation studies. The ATG explains that the appropriate examination steps depend on the nature and size of the project and the overall quality of the study. The process begins with understanding the study, its methodology, and its property classifications before moving into cost reconciliation, risk analysis, documentation, and more detailed examination procedures. For investors, understanding that sequence provides a useful way to evaluate whether a cost segregation study is built on evidence that can withstand scrutiny.

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Key Takeaways

• The IRS examination process begins by understanding what the cost segregation study claims and how the preparer reached those conclusions.
• Examiners review the study methodology, property classifications, cost allocation process, and supporting documentation in sequence.
• A study that clearly connects engineering conclusions, property classifications, and cost records gives an examiner fewer unanswered questions.
• Risk analysis helps the IRS determine which assets, classifications, costs, and documentation require closer examination.
• Investors can improve examination readiness by preserving contemporaneous records and maintaining a clear connection between the property and the study.
• The examination process can identify differences between the study, the taxpayer's books, depreciation schedules, and the underlying project records.
• An examination follows the evidence from classification to cost.

What Is an IRS Cost Segregation Examination?

An IRS examination of a cost segregation study is a review of whether the taxpayer properly classified property and determined the correct costs and recovery periods.

The ATG was specifically developed to help IRS examiners understand why cost segregation studies are performed, how they are prepared, what to look for when reviewing them, and when identified issues require further examination.

The ATG describes cost segregation as a factually intensive determination involving tax law and engineering analysis.

That is important.

An examination is not necessarily a review of a single percentage or a single line on a depreciation schedule.

The examiner may need to understand:

• What property was studied
• What methodology was used
• How individual assets were classified
• How costs were developed
• What documentation supports the conclusions
• How the study reconciles to the taxpayer's records

The ATG therefore approaches examination as a progression from understanding the study to testing its conclusions.

How Does the IRS Review a Cost Segregation Study?

The ATG provides suggested audit steps that generally begin with an initial risk analysis and then move into the examination itself.

The first step is reviewing the cost segregation study report.

The report should provide background about the property, explain the methodology used, identify the assets classified, identify applicable class lives and recovery periods, and explain the rationale and authority for the classifications.

The examiner then looks more closely at the property's unit groups and individual assets.

The ATG describes a Property Unit Summary as a listing of unit groups by asset class or recovery period, while the Property Unit Detail identifies the individual assets making up those groups and their cost basis.

From there, the examiner can evaluate whether the study's classifications and costs make sense when compared with the taxpayer's books, records, construction documentation, and the physical property.

The sequence is important.

Understand the study first. Then test the evidence supporting it.

Why Does the Examination Sequence Matter to Investors?

The examination sequence provides investors with a practical way to think about study quality.

A strong study should allow someone who was not involved in its preparation to understand how the conclusions were reached.

The ATG states that the quality of a study and report can influence the scope and depth of an examination. It also states that a quality study can help expedite the examination process and minimize the burden on taxpayers, practitioners, and examiners.

This does not mean a quality study guarantees an examination will not occur.

It means the study should be organized so that its engineering conclusions, classifications, and cost allocations can be followed.

For investors, that distinction matters.

Documentation is not simply something kept in a file in case the IRS asks for it.

Documentation is part of the reasoning chain.

A property classification should connect to the property's function.

The classification should connect to the supporting evidence.

The cost should connect to the underlying records.

That creates a traceable path from the physical property to the tax result.

For more on the characteristics of a quality study, see what defines a quality cost segregation study.

What Does the IRS Look for During Initial Risk Analysis?

Before conducting a full examination, the ATG directs examiners to perform a risk analysis.

The risk analysis compares the potential benefit of examining a particular issue with the resources required to complete the examination.

The examiner reviews the study's property descriptions and classifications and compares them with the applicable asset classes.

The ATG identifies several situations that can suggest audit potential.

These include:

• Mixed asset types in the same unit or group
• Building structural components classified as shorter-lived § 1245 property without appropriate support
• Minimal or no amounts assigned to land, non-depreciable land improvements, building property, or other longer-lived assets
• Unclear or creative asset descriptions that do not correspond with the construction records

The examiner can also request additional information when asset classifications are not readily understood.

The ATG specifically identifies plans, computer files, hardcopy records, permits, design studies, contractor payment records, contracts, purchase orders, invoices, and other contemporaneous records as potential sources of supporting evidence.

This illustrates an important point.

The IRS does not necessarily begin by assuming the study is wrong.

The examiner is trying to determine where the study presents audit potential and what additional evidence is needed to evaluate it.

How Does the IRS Evaluate Asset Classification?

Classification is one of the central issues in a cost segregation examination.

The ATG directs examiners to compare property descriptions and classifications with Revenue Procedure 87-56 and the applicable asset classes.

The examiner may review whether individual assets are properly classified and whether the descriptions accurately identify what the asset actually is.

This is where engineering evidence becomes important.

An asset name alone may not explain its tax classification.

The examiner may need to understand:

• What the asset does
• What it supports
• How it is installed
• What property it serves
• Whether it is part of a broader building system
• What documentation supports the classification

That approach aligns with the CostSegRx engineering philosophy.

Engineers classify assets, not buildings.

Function comes before classification.

Tax treatment follows the engineering conclusion rather than the other way around.

How Does the IRS Reconcile the Cost Basis?

Once the examiner understands the classifications, the next question is whether the costs assigned to those assets are supported.

The ATG instructs examiners to reconcile the cost basis in the study to the taxpayer's books and records and to review tax depreciation schedules for consistency.

The examiner may consider whether:

• The study reconciles to the fixed asset schedule
• Property appears on another depreciation schedule
• Separately acquired assets were duplicated
• The study contains unsupported cost basis
• Placed-in-service dates are correct
• The depreciation method is appropriate

This reconciliation is one reason cost segregation cannot be treated as an isolated engineering exercise.

The engineering analysis identifies the property.

The cost records establish the financial connection.

The tax records establish how the taxpayer actually reported the property.

A quality study needs those pieces to work together.

What Documentation Can the IRS Request?

The ATG includes a dedicated section on Information Document Requests, or IDRs.

It explains that appropriate documentation is needed to support the conclusions in a cost segregation study and that issue-focused IDRs help identify available records and establish a timeframe for producing them.

The ATG provides examples of information the IRS may request, including:

• Engagement letters
• Property locations and inspection information
• Blueprints and drawings
• Cost segregation reports
• Study computations and formulas
• Specific questions about segregated property
• Specific items and amounts

These requests are not limited to the final report.

They can reach into the records used to develop the report.

That is why contemporaneous documentation is so valuable.

Construction drawings, specifications, contractor records, invoices, site observations, photographs, and cost reconciliation records can help establish what actually existed and what it cost.

When Does Engineering Become Part of the Examination?

Some cost segregation examinations can be handled by the examiner without specialist assistance.

Others cannot.

The ATG identifies the Engineering Program within the IRS Large Business and International division as the principal source of technical expertise for examining cost segregation studies.

The ATG says studies with significant tax impact, numerous assets, complex assets, or estimated allocations between § 1245 and § 1250 property may require specialist assistance.

It specifically notes that studies involving estimated allocations between § 1245 and § 1250 property, particularly electrical or plumbing component systems, typically require an engineer experienced in construction and construction estimating.

This reinforces an important engineering principle.

When classification depends on how a physical system functions, the physical system matters.

An IRS engineer may need to understand the construction, installation, function, and cost development of the property before the classification issue can be resolved.

How Can Investors Improve Examination Readiness?

Investors do not control whether the IRS examines a return.

They can, however, control how well the property's engineering and cost history is documented.

Useful practices include:

• Preserve construction drawings and specifications
• Maintain final as-built drawings when available
• Keep contractor payment records and invoices
• Document capital improvements
• Preserve photographs of significant property conditions
• Maintain fixed asset and depreciation records
• Keep acquisition documents and appraisals
• Document the reasoning behind significant property classifications

These records become part of the property's engineering history.

They can also make future cost segregation work more efficient because the engineer does not have to reconstruct information that the owner already documented.

The CostSegRx philosophy treats cost segregation as an engineering inventory of the property's depreciable assets. That inventory can become useful beyond the original depreciation study because buildings evolve through renovations, equipment replacements, and other capital improvements.

Investors should also understand that examination readiness is not about producing the largest possible allocation.

It is about being able to explain the allocation.

For another perspective on study risk, see cost segregation strategy mistakes that can reduce investor ROI.

Illustrative Examination Example

Illustrative example only. Figures shown are estimated for demonstrative purposes only. Actual land allocations, asset classifications, depreciation, and tax results depend on the specific property, supporting documentation, engineering analysis, and taxpayer circumstances.

Assume a commercial property has a $10 million cost basis reflected in the taxpayer's records.

A cost segregation study identifies:

• $1.5 million of 5-year property
• $1 million of 15-year land improvements
• $7.5 million of 39-year nonresidential real property

The total study allocation equals the $10 million recorded basis.

During an examination, the IRS reviews the study and discovers that a separately purchased equipment package costing $250,000 also appears on another fixed asset schedule.

The issue is not simply that the study's $10 million total equals the taxpayer's books.

The examiner needs to determine whether the same $250,000 was counted twice.

If the equipment is duplicated, the study's asset classifications and cost basis need to be corrected.

The example demonstrates why reconciliation matters.

A study can have a mathematically correct total and still contain an allocation problem.

The examination process tests the connection between the study, the taxpayer's records, and the actual property.

What Happens After the Initial Review?

If the initial risk analysis identifies sufficient audit potential and applicable materiality thresholds are met, the ATG says the examination of the cost segregation issue should proceed.

The examiner then reviews the cost segregation report for examination purposes.

This can include requesting:

• The cost segregation report
• The engagement letter
• Information about the fee arrangement
• The methodology used
• The cost allocation process
• Sources of unit costs
• Contemporaneous documentation

The ATG also directs the examiner to consider whether cost basis was properly allocated to land, non-depreciable land improvements, and other property types that may not have been fully considered in the study.

From there, the examination can become more detailed depending on the issues identified.

This is why the first review matters.

The clearer the study is at the beginning, the easier it is to understand what questions actually require deeper investigation.

Engineering Principle

An Examination Follows the Evidence From Classification to Cost.

The IRS examination process described in the ATG is systematic.

The examiner starts by understanding the study.

Then the examiner evaluates methodology and classifications.

Then the cost basis is reconciled.

Then supporting documentation is examined.

When the issues are sufficiently complex, specialists may become involved.

That sequence mirrors the way a strong engineering-based study should have been developed in the first place.

Start with the property.

Understand how it functions.

Document what exists.

Classify the assets.

Develop and reconcile the costs.

Support the conclusions.

The objective is not to build a study around the fear of an audit.

The objective is to build a study where the engineering, documentation, classifications, and costs tell the same story.

An examination follows the evidence from classification to cost.