Short answer

The IRS does not keep its approach to cost segregation secret. Its Audit Techniques Guide, written for examiners, explains why studies are done, how they are prepared, and what to look for when one is examined. When a return with a study is selected, the examiner's requests follow the guide: the complete study, the workpapers and supporting documents, construction contracts and drawings, and the preparer's qualifications. The review then tests the methodology against the approaches the guide describes, the classification of each asset against the law, the allocation of costs against records or documented estimates, and the reconciliation against the taxpayer's own basis. A study built to the guide's elements can answer each request from its own file; one built on a percentage cannot. This article describes the process as the guide sets it out, the taxpayer's rights and appeal path, and how to prepare. It makes no claim about how likely an examination is. It is general education, not tax advice.

What the examiner asks for

The guide's information document request items map to the elements of a quality study.

RequestWhat it tests
The complete cost segregation study, including the narrative report and asset schedulesWhether the study describes its methodology, identifies the preparer, and presents an organized asset list
Workpapers and supporting documentsWhether the classifications and costs trace to evidence: take-offs, unit-cost sources, photographs, invoices
Construction contracts, pay applications, change orders, invoices, drawings and specificationsWhether the costs used match the records and whether the components exist as described
Closing statements, appraisals and the basis computationWhether the study reconciles to the actual basis and the land allocation is supported
The preparer's qualificationsWhether the person has the expertise and experience the guide's first element describes
Prior depreciation schedules and any Form 3115Whether a look-back was computed correctly and the method change was properly made

What the examiner tests

  1. Methodology. The guide ranks approaches from a detailed engineering approach using actual cost records down to rule of thumb, which it treats as the least reliable. A study that does not say which approach it used, or that used a percentage, starts at a disadvantage.
  2. Classification. Each asset placed in a shorter class is tested against the law on function: is this item a structural component of the building or personal property? The study's legal analysis is what the examiner reads; without one, the examiner supplies their own.
  3. Cost. Costs are traced to records where they exist and to documented estimates where they do not. Unit costs from the wrong year or region, or components priced above what the records support, are found here.
  4. Reconciliation. The allocated costs are compared with the taxpayer's basis and depreciation records. A total that does not tie, or a residual that absorbs an unexplained gap, is an adjustment waiting to be written.
  5. Related items. Land allocation, placed-in-service and acquisition dates, bonus depreciation eligibility, and any change in accounting method.

The taxpayer's side

Publication 556 explains the examination process, the taxpayer's rights during it, and the right to appeal a proposed adjustment. Owners are entitled to representation; advisers who practice before the IRS are governed by Circular 230, and the engagement letter with the practitioner should say what the practitioner will do if the study is questioned. A proposed adjustment can be appealed within the IRS and, after that, in court; the records that decide the outcome are the ones assembled when the study was done.

Preparing before there is anything to prepare for

  • Build the study to the guide's elements in the first place. Every request above is answered by a file that already exists.
  • Keep the file together: the study, workpapers, source documents, engagement letter, the adviser's computations and elections, and the depreciation schedules, for as long as they may be material, which for a building is the entire holding period and beyond.
  • Know who answers. The practitioner's role in an examination, and the fee, belong in the engagement letter; the adviser represents the return.
  • Keep the dates and the land split documented. They are examined every time.
  • Do not improvise. A file assembled after a request, with reconstructed take-offs and newly discovered invoices, reads as what it is.

A worked sequence

Picture an examination of a return that used a study on an apartment building. The examiner's first request is the study and the workpapers. The practitioner's file produces the report, the document index, the site record with photographs, the take-off sheets, the unit-cost sources, the classification memos, the indirect cost schedule and the reconciliation. The second request is the construction and basis records: the closing statement, the appraisal used for the land split, the pay applications for the renovation. The third is the preparer's qualifications: a name, credentials and experience stated in the report. The examiner then samples: three classified items traced to their memos and their costs; the land split checked against the appraisal; the reconciliation re-added; the dates compared with the certificate of occupancy and the contract. Where the file answers each step, the examination is a review of evidence. Where it does not, the examiner reconstructs the study on the IRS's terms.

What the guide does not say

The guide does not say that a cost segregation study increases the likelihood of examination, and this article makes no such claim. It does not disapprove of cost segregation; it describes how to prepare and review a study properly. It does not approve any preparer, method or product, and no vendor can truthfully say a product is approved by the IRS on the strength of it.

Common findings, from the guide's own list of elements

  • No identified preparer, or a preparer whose qualifications are not stated.
  • No described methodology, or a rule-of-thumb allocation.
  • Components classified as personal property with no legal analysis.
  • Costs that do not trace to records or to a documented estimate.
  • A reconciliation that does not tie to basis, or none.
  • Land allocated without evidence.
  • Renovations and acquisitions merged, with wrong dates.
  • A look-back applied without a proper method change.

What people ask on Reddit and other forums

"Will cost seg get me audited" is the most common worry in the "cost segregation reddit" threads on r/realestateinvesting and r/tax. The searches that lead people to these threads are usually phrased "cost segregation audit", "IRS audit techniques guide cost segregation" and "cost segregation examination".

"Does a study raise my audit risk?" No public IRS statement supports that claim, and this article makes none. The guide describes what examiners look for if a return is examined, which is the part you control.

"What will the IRS ask for?" The complete study, the workpapers and supporting documents, construction records and drawings, basis documents and the preparer's qualifications, per the guide.

"My study is a two-page summary. Am I in trouble?" You have a study that cannot answer the requests. Ask a practitioner to review it against the guide's elements and tell you what is missing.

"Who deals with the IRS, me or the cost seg firm?" Your adviser represents the return. The practitioner's role should be in the engagement letter.

Questions people also ask

What is the IRS Cost Segregation Audit Techniques Guide?

Publication 5653, a guide written for IRS examiners explaining why studies are done, how they are prepared and how to review them. It is public and is the clearest statement of what the IRS expects.

What documents does the IRS request in a cost segregation examination?

The complete study, the workpapers and supporting documents, construction contracts and drawings, basis records and the preparer's qualifications, among other items.

Does the IRS approve cost segregation studies?

No. It publishes expectations for examiners; it approves no preparer, method or product.

Can I appeal a cost segregation adjustment?

Yes. Publication 556 explains examination and appeal rights.

How long should I keep the study?

As long as it may be material, which for a depreciated building is the whole holding period and the period after sale during which the return can be examined.

Sources