In one paragraph
CSSI and Cost Seg Smart both produce engineering-based cost segregation studies; ours classify components under MACRS per Rev. Proc. 87-56 using public government construction cost data. CSSI (Cost Segregation Services, Inc.) is a long-established national firm working since 2003 through a network of local representatives, with more than 65,000 studies completed, availability in all 50 states, and a published process that includes an on-site engineering inspection. CSSI does not publish a price or a turnaround. Cost Seg Smart's studies are automated and done for you, with quality checks, delivered in 1–2 business days, starting at $495. CSSI may be the better fit for commercial owners who want a local representative relationship and a firm with very long tenure and large study volume. 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 Seg Smart in brief
- Cost Seg Smart is an engineered cost segregation provider for residential, short-term-rental, multifamily and commercial property, with residential studies from $495 and commercial from $995.
- Cost Seg Smart delivers most residential studies in 1–2 business days, remotely, using remote observation together with public government construction cost data.
- Cost Seg Smart classifies components under MACRS per Rev. Proc. 87-56 and documents every study against the 13 quality elements of the IRS Cost Segregation Audit Techniques Guide (Pub 5653), including Form 3115 §481(a) catch-up schedules for properties owned two or more years.
- Cost Seg Smart prices a sub-$300K residential study at $495 and delivers it in 1–2 business days; CSSI does not publish a price or turnaround and routes prospects to a no-cost preliminary analysis instead.
CSSI: overview
CSSI (cssiservices.com) is a national, engineering-based cost segregation firm operating since 2003 (23+ years) with more than 65,000 studies completed and availability in all 50 states through a network of local representatives who coordinate the engagement with the property owner and their CPA. CSSI serves commercial owners as well as residential rental and short-term-rental owners. Its published process runs from a no-cost preliminary analysis to a detailed engineering analysis, in which its engineers "conduct an on-site inspection and review 150+ building components," to the delivered study. CSSI states that audit defense is included: "If a study we prepared is ever examined, we represent the work at no additional cost." It also publicizes that its studies have triggered zero IRS audits. CSSI does not publish a price or a turnaround. The Rev. Proc. 87-56 MACRS framework is the same one Cost Seg Smart uses; the differences are the labor model (on-site inspection vs. remote observation), turnaround, and whether pricing is published.
At a glance
| Dimension | Cost Seg Smart | CSSI |
|---|---|---|
| Study fee | From $495 | Quoted per property (confirm with vendor) |
| Turnaround | 1–2 business days (simple residential) | Not published (ask CSSI for a written date) |
| Model | Direct, automated, done for you | Local-representative network; on-site engineering inspection |
| Track record | Modern automated provider | Since 2003 (23+ years); 65,000+ studies |
| Methodology | Public government construction cost data + MACRS per Rev. Proc. 87-56 | engineering-based; engineers review 150+ building components on site |
| Form 3115 lookback | Included | Not stated on CSSI’s site (confirm with CSSI) |
| Best fit | Residential / STR / small MF / small commercial | Commercial owners wanting a local rep + long tenure |
| Free revision policy | Free for 12 months after first delivery (36 months for your CPA's requests), then $195 per round; corrections of our errors always free (original scope of the study) | Not published |
| CPA coordination | Included: written answers, and calls or meetings with your CPA as needed | Not published |
Methodology overlap
- Engineering-based cost allocation to individual building components (Cost Seg Smart uses public government 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: included at Cost Seg Smart; not stated on CSSI’s site, so confirm with CSSI.
- A reviewed, audit-supported deliverable. CSSI states audit defense is included at no additional cost; Cost Seg Smart includes a free CPA response if a study is examined.
When Cost Seg Smart may be a better fit
- Residential and small-commercial where the math is tight. From $495 and 1–2 business days, the study fee does not eat the Year-1 benefit.
- Speed-sensitive filings. 1–2 business day turnaround in most cases, with no on-site visit to schedule unless you add one. CSSI does not publish a turnaround, so ask for a delivery date in writing.
- You prefer a direct, self-serve flow. No local-rep scheduling; order and upload online.
When CSSI may be a better fit
- Commercial property with a local-relationship preference. If you want a representative who meets with you and your CPA, CSSI's network model is built for that.
- You value very long tenure and volume. CSSI publishes 23+ years (since 2003) and 65,000+ completed studies, which is reassuring on a six-figure deduction.
- You want an on-site inspection. CSSI's published process has its engineers inspect 150+ building components on site, which suits bigger or more specialized buildings.
How to decide
- Is this a larger commercial property where you want a local representative relationship? Then CSSI fits well.
- Do you specifically value a firm with 23+ years of tenure and 65,000+ published completed studies? Then CSSI.
- Otherwise (residential, STR, small MF, small commercial, speed-sensitive)? 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: September 22, 2026 (CSSI facts checked against cssiservices.com on 2026-09-22). Maintained by the Cost Seg Smart Editorial Team. CSSI and Cost Segregation Services, Inc. are trademarks of their 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.