Do It Yourself Cost Segregation Study

By Jason Watson, CPA
Posted Sunday, July 12, 2026

The fee for a cost segregation study varies between $750 and a bajillion dollars. In the rental property world, you will often hear people refer to two broad categories: “do it yourself” cost segregation and fully engineered cost segregation.

That language is not perfect. A do-it-yourself cost segregation report is usually not a separate methodology. In many cases, it is a residual estimation report delivered through software, a portal, a guided questionnaire or some other technology-assisted process. Said differently, the methodology might still be residual estimation, modeling, survey-based inputs, cost databases and prior study data. The delivery just feels more DIY.

The fully engineered report, on the other hand, feels more like a property appraisal. There might be a virtual or in-person site visit, measurements, pictures, construction analysis and a qualified person dissecting the property to create the 5-year, 7-year and 15-year piles. As mentioned earlier, fully engineered reports for many rental properties under $2 million(ish) might range from $2,500 to $6,000, although pricing continues to compress as providers use better technology, virtual visits and better data.

For smaller or more standard rental properties, a DIY or software-assisted residual estimation report can still make sense. There is a depreciable property value of about $1.5 to $2 million depending on the provider where things change. Below that value, the statistical reliability and therefore predictability is very good, which is what makes the DIY approach reasonable down-market. For the same reason, many DIY providers will only take properties up to a certain size, such as a square footage ceiling or a unit count limit like four units.

Beyond those thresholds the statistical shortcuts get shakier, and a fully engineered report starts to make more sense. The report is generally relying on a large pool of prior reports, property data, cost databases and statistical relationships to estimate how much of your depreciable basis belongs in shorter-life property. It might ask for basic property vitals such as address, age, purchase price, square footage, property type and photos, plus a quickie survey of the stuff inside.

What stuff? According to CostsegEZ.com, here is a quick list-

• Removable floor coverings (i.e., carpet, vinyl, LVP, floating wood)

• Kitchen cabinets and countertops

• Kitchen appliances (including mechanical, electrical, plumbing connections)

• Laundry appliances (including mechanical, electrical, plumbing connections)

• Window treatments

• Ceiling fans

• Electrical wiring and outlets for telephones (really?!), televisions, internet

• Closet shelving

• Decorative trim and wall coverings

• Decorative light fixtures (including electrical connections)

• Hot tubs and pool equipment (see our hot tub conundrum)

• Security systems

• Furniture and decor

• Window air conditioning units

WCG CPAs & Advisors has a similar list that we use for renovations where we do a “poor man’s” version of cost segregation when a rental property owner details out a renovation or rental rehab. Keep in mind- The IRS wants whatever you do to be “factually intensive” which we belabor here in a bit. Like 2 minutes from now.

How does a do it yourself cost segregation report work again? Said another way, the cost segregation report is relying on a slew of prior reports to homogenize the data and draw correlations to the basic property vitals and a survey of certain components. It is not necessarily measuring every screw, outlet and cabinet hinge.

Two hairs are worth separating here. The legal theory, reclassifying qualifying items as Section 1245 property rather than part of the building, has been upheld in court, most notably Hospital Corporation of America. The methodology behind DIY is residual estimation, which the IRS lists as a recognized approach in its own Audit Techniques Guide, though it sits below the detailed engineering approaches on the reliability scale.

What no court has done is bless a specific cost segregation methodology by name. Estimates are allowed, they just have to be supported. Is there a risk? Yes. Are there standards? Yes, but not in the way you might expect.

According to IRS Publication 5653 Cost Segregation Audit Techniques Guide (ATG)–

Neither the Internal Revenue Service (Service) nor any group or association of practitioners has established any requirements or standards for the preparation of cost segregation studies. The courts have addressed component depreciation but have not specifically addressed the methodologies of cost segregation studies.

The Service has addressed this issue but only briefly, i.e., Revenue Ruling 73-410, 1973-2 C.B. 53, Private Letter Ruling (PLR) 7941002 (June 25, 1979), Chief Counsel Advice Memorandum 199921045 (April 1, 1999). These documents all emphasize that the determination of § 1245 property is factually intensive and must be supported by corroborating evidence. In addition, an underlying assumption is that the study is performed by “qualified individuals” and “professional firms” that are competent in design, construction, auditing, and estimating procedures relating to building construction (See PLR 7941002).

Despite the lack of specific requirements for preparing cost segregation studies, taxpayers still must substantiate their depreciation deductions and classifications of property. Substantiation using actual costs is more accurate that using estimates. However, in situations where estimation is the only option, the methodology and the source of any cost data should be clearly documented. In addition, estimated costs should be reconciled back to actual costs or purchase price.

The big takeaway from the blurb is the phrase “factually intensive.” It appears 7 times in the ATG. When shopping for a DIY cost seg provider, does the sample report feel factually intensive? Does it explain the property data used? Does it show the methodology? Does a human review the output? Does the provider offer audit support or the ability to upgrade into a fuller report if needed?

For the actual report, does it reconcile back to depreciable basis? Do not be discouraged from using a do-it-yourself cost segregation provider. Many are extensions of fully engineered cost segregation firms, and many are perfectly reasonable for smaller, simpler rental properties. But do not confuse “easy” with “unsupported.” If the report gives you a big deduction but cannot explain where the numbers came from, you might have purchased a tax problem with a cover page.