In one paragraph
Seneca Cost Segregation and Cost Seg Smart both produce engineering-based cost segregation studies that follow the IRS Cost Segregation Audit Techniques Guide. Seneca works with rental, commercial, owner-occupied business, new-build and renovation property across all 50 states, reviewing each property virtually or on site. It does not publish prices: per their FAQ, fees depend on square footage, property type and complexity, and they provide a free, no-money-down proposal before a study. Per their homepage, most studies are completed in 2-4 weeks, with rush prioritization available for deadlines. Their site states a common feasibility threshold of $300K+ property value (How It Works; the homepage says $450,000) or $500,000 in improvements, and their featured single-family case study is a $370,000 purchase. Cost Seg Smart's automated studies work from satellite imagery, county assessor records, and structured property data, with internal technical review & QC, usually delivered the next business day, starting at $495 for residential under $300K basis and $1,995 for commercial. In our view, Seneca is a reasonable fit if you want a per-property quote, an optional on-site review, and their written money-back terms. Cost Seg Smart is the fit if you want a published fixed price and a schedule the next business day, especially for residential, STR, small multifamily, and well-documented commercial property.
Disclosure: Cost Seg Smart operates this comparison and is one of the firms compared here. See the methodology page for our standalone documentation. Seneca details on this page were checked against senecacostseg.com on 2026-09-22; tell us at research@costsegsmart.com if anything has changed.
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 $1,995.
- Cost Seg Smart delivers most residential studies the next business day, remotely, using remote observation together with industry-standard 2026 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 usually by the next business day; Seneca Cost Segregation does not publish prices (fees are quoted per property, with a free proposal) and states that most studies are completed in 2 to 4 weeks.
At a glance: Seneca Cost Segregation vs Cost Seg Smart
| Dimension | Cost Seg Smart | Seneca Cost Segregation |
|---|---|---|
| Price (residential under $1M) | $495–$995 | Quote-based (not published); residential rentals are in scope per their site |
| Price ($1M–$5M commercial) | $3,295–$4,995 | Quote-based (not published) |
| Turnaround | Usually the next business day | 2–4 weeks for most studies; rush may be available (no published timeframe) |
| Site visit | No (remote observation) | Virtual or on-site review, depending on the property and preference |
| Methodology | industry-standard 2026 construction cost data + MACRS + ATG | Engineering-based analysis following the IRS ATG (Pub 5653); cost-data source not named |
| Audit defense | Internal technical review & QC + free CPA methodology support, no expiry | Seneca AuditDefense: responds to IRS questions; refunds 100% of the fee if Seneca caused an issue resulting in a >5% depreciation adjustment |
| Form 3115 lookback | Included | Supported (Form 3115 catch-up, per their FAQ) |
| Best fit | Residential / STR / small MF / sub-$2M commercial | Per their site: income-producing and business property from ~$300K–$450K value or $500K+ improvements |
| Specialty signal | Automated pipeline, speed, transparent pricing | Free no-money-down proposal, virtual or on-site review, conditional money-back guarantee |
Methodology overlap (what each firm publishes)
Both firms reclassify building components into shorter recovery periods and follow the IRS audit guide. Where the two differ in what they publish:
- Construction cost data. Cost Seg Smart uses industry-standard 2026 construction cost data with regional cost multipliers. Seneca does not name a cost-data source on its site.
- Recovery periods. Both reclassify qualifying components into 5-, 7- and 15-year property instead of 27.5 or 39 years. Cost Seg Smart classifies under MACRS per Rev. Proc. 87-56; Seneca describes the same reclassification without citing the revenue procedure (How It Works).
- IRS Cost Segregation Audit Techniques Guide (Pub 5653). Seneca states it follows the ATG (About Us). Cost Seg Smart documents every study against the guide's 13 quality elements.
- Prior-year property. Per their FAQ, past depreciation can be reclaimed with Form 3115 without amending prior returns. Cost Seg Smart produces the §481(a) catch-up schedule under DCN 7.
- Reviewed deliverable. Seneca describes engineers who assess each property; its site does not state a PE stamp or signed attestation. Cost Seg Smart includes internal technical review & QC.
What differs is the labor model and the pricing model. Seneca reviews each property virtually or on site and quotes each engagement individually. Cost Seg Smart's pipeline is built around structured-data observation at published fixed prices. In our view, an on-site review matters most for specialty build-outs (commercial kitchens, hotel furnishings, spa and pool installations, medical or manufacturing equipment) and matters little for well-documented property types.
Where Cost Seg Smart wins
When should I choose Cost Seg Smart over Seneca Cost Segregation?
- You want the price before you start. Seneca quotes each property individually and publishes no fee schedule. Our pricing is published (residential from $495, multifamily 2–4 from $995), so the Year-1 return on the study fee is known up front. Seneca also states a common feasibility threshold of $300K+ property value (its homepage says $450,000), so smaller rentals may fall below their range.
- Well-documented commercial. Office, retail and mixed-use property that is well documented (county assessor records, RentCast property API, standard commercial subtype) rarely needs an on-site review, in our view.
- Speed-sensitive filings. Usually next-business-day turnaround vs the 2–4 weeks Seneca states for most studies (they offer rush prioritization but publish no rush timeframe). If your CPA needs the schedule for a return on extension, the gap can be decisive.
- Portfolio operators. A 5–10 property portfolio in an afternoon at published per-property prices, vs individually quoted engagements.
- Buyers weighing audit-defense terms. Seneca's money-back guarantee applies only if Seneca caused an issue resulting in a >5% depreciation adjustment. Cost Seg Smart provides internal technical review & QC + free written methodology support to your CPA for the life of the study; compare the two sets of terms against the price difference.
Where Seneca Cost Segregation wins
When should I choose Seneca Cost Segregation over Cost Seg Smart?
- You want someone on site. Seneca offers virtual or on-site review depending on the property, timing and your preference (About Us). For specialty build-outs such as commercial kitchens, hotel furnishings, or spa and pool installations, first-hand observation can change the allocation, in our view.
- You want a free proposal first. Per their FAQ, Seneca provides a no-money-down proposal before a study is done, so you see the fee for your specific property before committing.
- You want a written money-back condition. Seneca AuditDefense states that Seneca will respond to IRS questions about its studies and refund 100% of its fee if, in an audit, Seneca is found to have caused an issue resulting in a >5% adjustment to depreciation (published terms).
- You found Seneca through its educational content. Their post Can I Do My Own Cost Segregation Study? covers the DIY question; if you arrived that way, their paid engagement is a natural next step.
How to decide
Three questions to ask:
- Does your property need an on-site review? For specialty build-outs, Seneca's on-site option may be worth a quoted fee. For residential, STR, small multifamily, or standard commercial, in our view the on-site visit rarely changes the schedule materially.
- Do guarantee terms matter to your purchase? Seneca refunds its fee only if it caused an issue resulting in a >5% depreciation adjustment. If you are comfortable with internal technical review & QC + free CPA response on examiner requests, Cost Seg Smart's terms cover the audit-defense scope.
- Do you need the schedule this month or this week? Cost Seg Smart's usual next-business-day turnaround vs the 2–4 weeks Seneca states for most studies is the deciding factor on speed.
If you want to see the math on a specific property before deciding, our free calculator gives a Year-1 estimate in 30 seconds. Full methodology details are at /methodology/, pricing tiers at /cheap-cost-segregation/.
For a side-by-side methodology view across cost segregation firms, costsegregationreviews.com, a review site we operate, publishes how different firms approach engineering studies.