Our Cost Segregation Methodology: 13 Principal Elements Compliant

Every WeCostSeg engagement follows the detailed engineering approach from actual cost records described in Chapter 3 of IRS Publication 5653. Every report addresses all 13 Principal Elements of a Quality Cost Segregation Study from Chapter 4. The methodology is the same across our three pricing tiers; the difference between tiers is scope and inspection depth, not methodology.

The IRS Cost Segregation Audit Techniques Guide

The IRS published the Cost Segregation Audit Techniques Guide in 2004 with major updates in 2022 and February 2025. The Guide describes how examiners evaluate cost segregation studies and what constitutes a quality study. Reading the Guide is the most useful preparation any investor or CPA can do. The current edition is available at irs.gov/pub/irs-pdf/p5653.pdf. Our summary is on the IRS Pub 5653 plain-English page.

The six methodologies (Pub 5653 Chapter 3)

1. Detailed engineering approach from actual cost records
2. Detailed engineering cost estimate approach
3. Survey or letter approach
4. Residual estimation approach
5. Sampling or modeling approach
6. "Rule of thumb" approach

The Guide describes the detailed engineering approach from actual cost records as the most accurate. We default to this method. The residual estimation and rule-of-thumb approaches are explicitly identified as the least defensible.

The 13 Principal Elements (Pub 5653 Chapter 4)

1. Preparer's qualifications and credentials
2. Detailed cost-by-cost itemization with appropriate justification
3. Methodology disclosure
4. Allocation of indirect costs
5. Documented assumptions and limitations
6. Identification of personal property and land improvements
7. Treatment of intangibles and land
8. Documented support for asset classification (Section 1245 vs 1250)
9. Recovery period justification
10. Photographic documentation
11. Source documentation referenced and archived
12. Mathematical accuracy and computation verification
13. Citations to case law and revenue rulings where relevant

How our reports address each element

Every WeCostSeg study report opens with a methodology disclosure citing the Pub 5653 detailed engineering approach. Each asset line carries a recovery period justification and a Section 1245 or 1250 classification with a brief rationale. Photo logs are archived for the five-year audit defense period. Citations to relevant Tax Court opinions (HCA v. Commissioner is the foundational case) and IRS revenue rulings are included where applicable.

Why "engineering" matters

The Audit Techniques Guide consistently uses the word "engineering" in describing what distinguishes a quality study from a questionnaire-driven product. The engineer's qualifications are Principal Element #1. Software that returns a study without engineer review fails this element. Our Rapid Report tier is software-assisted but always engineer-reviewed and engineer-signed; this is what distinguishes it from DIY tools.

Frequently asked questions

What methodology does WeCostSeg use for cost segregation studies?

WeCostSeg uses the detailed engineering approach from actual cost records, the first of the six methodologies in Chapter 3 of IRS Publication 5653. The IRS Audit Techniques Guide identifies this method as the most accurate and most defensible. Every report documents all 13 Principal Elements from Chapter 4 of Pub 5653.

What is IRS Publication 5653?

IRS Publication 5653 is the Cost Segregation Audit Techniques Guide. The IRS first published it in 2004 with major updates in 2022 and February 2025. It describes the six approved methodologies in Chapter 3, the 13 Principal Elements of a Quality Study in Chapter 4, and industry-specific guidance in Chapter 7. The current PDF is at irs.gov/pub/irs-pdf/p5653.pdf.

What are the 13 Principal Elements of a Quality Cost Segregation Study?

The 13 Principal Elements cover preparer credentials, cost-by-cost itemization, methodology disclosure, allocation of indirect costs, documented assumptions, identification of personal property and land improvements, treatment of intangibles and land, Section 1245 vs 1250 classification, recovery period justification, photographic documentation, source documentation, mathematical accuracy, and citations to case law. Every WeCostSeg report addresses all 13.

What is Hospital Corporation of America v. Commissioner?

Hospital Corporation of America v. Commissioner, 109 T.C. 21 (1997), is the landmark Tax Court case that authorized component depreciation for real estate. The IRS acquiesced to the decision, which established the legal foundation for modern cost segregation studies. Every WeCostSeg report cites HCA v. Commissioner where relevant per Principal Element 13.

Which cost segregation methodologies does the IRS consider least defensible?

Chapter 3 of IRS Pub 5653 explicitly identifies the residual estimation approach and the rule-of-thumb approach as the least defensible of the six methodologies. WeCostSeg does not use either. Every engagement defaults to the detailed engineering approach from actual cost records, which the Audit Techniques Guide describes as the most accurate.

Does WeCostSeg's Rapid Report tier meet the 13 Principal Elements?

Yes. The Rapid Report tier is software-assisted but always engineer-reviewed and engineer-signed. Principal Element 1 requires preparer qualifications, and software that returns a study without engineer review fails this element. WeCostSeg Rapid Reports at $795 include full engineer review, distinguishing them from DIY software products.

How does WeCostSeg document Section 1245 vs Section 1250 classification?

Each asset line in a WeCostSeg report carries a Section 1245 or Section 1250 classification with a written rationale per Principal Element 8. Personal property (5-year and 7-year) falls under Section 1245. Real property and structural components (27.5-year residential, 39-year nonresidential) fall under Section 1250. Land improvements (15-year) fall under Section 1245.

Where do photos and source documents live during the 5-year audit defense window?

Photo logs and source documentation are archived for the full five-year audit defense period per Principal Elements 10 and 11. If the IRS opens an examination within five years of report delivery, WeCostSeg produces the archived photographic and source documentation at no additional charge as part of the included audit defense.