In one paragraph
Cost Segregation Authority and Cost Seg Smart both produce IRS ATG-aligned engineered cost segregation studies using industry-standard construction cost data and MACRS classification per Rev. Proc. 87-56. Cost Segregation Authority (CSA) is an established engineering-based firm, working since 2006 with more than 28,000 studies completed, that also handles energy-efficiency tax incentives such as §179D and 45L alongside cost segregation. Cost Seg Smart's studies are automated and done for you, with internal technical review and QC, delivered in under one hour starting at $495. Cost Segregation Authority may be the better fit when you want a single engineering firm to bundle cost segregation with energy incentives, or for larger commercial work. Cost Seg Smart may be the better fit for residential and small-commercial where speed and study cost decide the ROI.
Disclosure: Cost Seg Smart operates this comparison and is one of the firms compared here. See the methodology page for our standalone documentation.
Cost Segregation Authority: overview
Cost Segregation Authority (costsegauthority.com), headquartered in Lindon, Utah, has provided engineering-based cost segregation studies since 2006, with more than 28,000 studies completed. Beyond cost segregation, CSA also works on energy-efficiency tax incentives such as the §179D deduction and the 45L credit, which makes it a fit for owners who want those services bundled with one engineering firm. The cost segregation methodology and Rev. Proc. 87-56 MACRS framework are the same ones Cost Seg Smart uses; the differences are the labor model, turnaround, study cost, and the energy-incentive bundling.
At a glance
| Dimension | Cost Seg Smart | Cost Segregation Authority |
|---|---|---|
| Study fee | From $495 | Quoted per property (confirm with vendor) |
| Turnaround | Under 1 hour (simple residential) | Multi-week (engineering engagement) |
| Energy incentives (179D / 45L) | See /179d/ | Bundled with the firm |
| Track record | Modern automated provider | Since 2006; 28,000+ studies |
| Methodology | industry-standard construction cost data + MACRS per Rev. Proc. 87-56 | engineering-based, construction cost data + MACRS |
| Form 3115 lookback | Included | Supported |
| Best fit | Residential / STR / small MF / small commercial | Commercial; owners wanting energy incentives bundled |
Methodology overlap (both firms)
- Industry-standard construction cost data with regional multipliers.
- MACRS classification per Rev. Proc. 87-56 (IRS Pub. 946 Appendix B).
- IRS Cost Segregation Audit Techniques Guide (Pub 5653) 13-element framework.
- Form 3115 §481(a) lookback for properties owned 2+ years.
- A reviewed, audit-supported deliverable at both firms.
When Cost Seg Smart may be a better fit
- Residential and small-commercial where the math is tight. From $495 and under an hour preserves the Year-1 benefit.
- Speed-sensitive filings. 60-minute turnaround vs. a multi-week engagement.
- You only need the cost-seg study. If energy incentives are not in scope, the bundle is not a deciding factor.
When Cost Segregation Authority may be a better fit
- You want energy incentives bundled. If §179D or 45L apply to your property, having one engineering firm handle both alongside cost segregation is convenient.
- Larger or specialty commercial. An on-site engineering engagement can add accuracy on bigger or unusual buildings.
- You value long tenure. Nearly two decades and tens of thousands of studies are reassuring on a large deduction.
How to decide
- Do you need §179D or 45L energy incentives alongside cost segregation? Then a firm that bundles them, like CSA, is convenient.
- Is this a larger or specialty commercial property wanting on-site engineering? Then CSA fits well.
- Otherwise (residential, STR, small MF, small commercial, speed-sensitive, cost-seg only)? Then Cost Seg Smart.
See the math with our free calculator. Methodology at /methodology/; pricing at /cheap-cost-segregation/; the full firm landscape at best cost segregation companies.
Last reviewed: June 2026. Maintained by the Cost Seg Smart Editorial Team. Cost Segregation Authority is a trademark of its respective holder. No affiliation. This comparison is informational; both firms produce IRS ATG-aligned engineered cost segregation studies. Confirm pricing and scope directly with each vendor.