Sources
Sources & Citations
Every IRS publication, Treasury regulation, court case, ASCSP standard, and data source we use — with direct links and what each is for.
Cost segregation is a tax strategy with a deep, well-documented authority base. Below is the full list of primary sources our content and engine are checked against. Every claim on this site links back to one of these — search this page for any source you want to verify against.
IRS publications
Primary source for asset-class lives, MACRS recovery periods, and bonus depreciation rules. Cited on every page that mentions MACRS, asset class life, or 5/7/15/27.5/39-year property.
Examination criteria for cost segregation studies. Our methodology is explicitly aligned with this guide. Cited anywhere we describe what makes a study 'IRS-defensible.'
The form used to claim missed depreciation under §481(a). Cited on every lookback / catch-up depreciation page.
The form used to report depreciation claimed in the tax year. Cited on pages explaining how cost-seg results land on a return.
Authoritative source on rental-property depreciation and passive activity rules.
Authoritative source on §469 passive activity loss limitations and the real estate professional exception.
Treasury regulations & US Code
Foundational regulation defining how property is depreciated under MACRS.
General Asset Account (GAA) rules and partial-disposition elections.
The class-life table that drives 5-year, 7-year, and 15-year property classifications. Foundational for any cost-seg engineering analysis.
The statute behind bonus depreciation. Pre-OBBBA phase-down was 80% (2023), 60% (2024), 40% (2025). OBBBA permanently restored 100% for 2025+.
The passive activity loss rules. §469(c)(7) is the real estate professional exception. §469(i) is the $25,000 active-participation allowance for non-REPS investors.
The statute that authorizes the lookback / catch-up depreciation adjustment via Form 3115.
Cited on commercial energy-efficiency angle pages.
Court cases
Landmark Tax Court case establishing that engineering-based cost-seg methodology is acceptable. Foundational precedent for the entire industry.
Multifamily cost-seg case clarifying the line between structural building components and §1245 personal property.
Industry standards
Industry standards body. Our methodology is aligned with ASCSP's Member Handbook and Minimum Quality Standards (MQS) for engineering-based studies.
Engineering norms referenced for site-work, foundation, and structural component classifications.
Engineering norms for concrete component lifing.
Data sources
The cost database used as the engineering-grade baseline for component pricing in our engine. RSMeans is the standard reference for construction cost estimation in the US.
The Bureau of Labor Statistics PPI series is the time-adjustment input that escalates RSMeans 2024 baseline costs to current-year dollars by region.
County assessor data, rental comps, and property characteristics — used to enrich and cross-verify customer-supplied property details.
Building type, landuse, and footprint data for property verification. No personal data; bulk geographic features only.
Geographic context (population, income, building stock) for location pages and benchmarks report.
Our open-data research
Our open-data report (n=260 studies, CC-BY licensed). The benchmark dataset is the source for typical reclassification percentages, year-1 federal tax savings, and US provider pricing distribution claims on this site.
Found something missing or outdated?
Email research@costsegsmart.com. Substantive corrections are dated and noted on the affected page. Tax law updates trigger a full content sweep within 30 days of effective date.