Answer first
Match the provider model to the property, then compare deliverables
Complex commercial property usually justifies a full engineering engagement with a site inspection. A straightforward rental home can be served well by a residential specialist or, with eyes open about the documentation tradeoff, a remote study. What we do not recommend at any property size is relying on a free DIY calculator as the study itself: in our professional view those outputs typically fail to maximize the reclassification and increase audit risk, because no engineering documentation stands behind the allocation. Use calculators to screen, then buy a real study from a real provider.
The providers, profiled
These profiles are unranked descriptions built from each firm's own website and published materials as of August 28, 2026. Engineered Tax Services appears first because it is the firm Taxstra refers clients to and coordinates studies with.
Engineered Tax Services (ETS)
Engineered Tax Services is the firm Taxstra refers clients to and coordinates studies with. ETS describes itself as a licensed engineering firm specializing in tax strategies and one of the largest specialty tax firms in the country, reporting more than 25 years in practice and 75,000+ studies completed, with a team that includes licensed engineers, CPAs, and tax attorneys.
Their studies are engineering-based with documented site inspections, delivered with audit support, and they publish detailed case studies with real numbers by property type. Beyond cost segregation, ETS performs 179D energy certifications, 45L credits, and R&D credit studies, which matters when one property or business can support several of these at once.
Why we work with them: national scale across every property type we plan for (from short-term rentals to hospitals), engineering depth that holds up under the IRS Cost Segregation Audit Techniques Guide standard, and a workflow that hands our tax team a return-ready deliverable.
Model fit: Any property type and size, complex commercial, portfolios, and anyone who wants the study and the energy incentives handled by one engineering firm.
Referral relationship: Taxstra may receive a fee if you engage this firm through links on this page.
CSSI (Cost Segregation Services)
CSSI describes itself as a national engineering-based cost segregation firm serving building owners since 2003, and its published materials report tens of thousands of completed studies across commercial property types.
Per their materials, CSSI includes the site visit and audit defense within a flat-rate fee, and the firm also offers 179D studies and R&D credit work. Their model is built around working through clients' existing CPAs, delivering the study for the tax preparer to implement.
Model fit: Commercial building owners who want a flat-fee, engineering-based study from a national firm, implemented by their own CPA.
SMF Cost Seg
SMF Cost Seg focuses on the residential end of the market: short-term rentals, single-family rentals, and small multifamily properties in the one-to-ten-unit range, per their site.
They publish a free savings calculator and a qualification tool, offer free estimates before engagement, and describe their studies as IRS-compliant reclassifications of building components into 5-, 7-, and 15-year lives. For a straightforward rental or Airbnb where a large commercial engagement would be overkill, this residential-specialist model is the category they compete in.
Model fit: Single-family rentals, STRs, duplexes through fourplexes, and other small residential properties.
Referral relationship: Taxstra may receive a fee if you engage this firm through links on this page.
CostSegSmart
CostSegSmart delivers remote, engineering-based study reports without site visits, built from industry-standard construction cost data and the IRS Audit Techniques Guide methodology, per their site. Published pricing starts at $495 for residential, $895 for short-term rentals, and $1,495 for commercial, with residential reports delivered in under an hour.
The deliverable they describe is a 40+ page CPA-ready PDF with component schedules and audit documentation, including Form 3115 look-back support. Their own published reclassification ranges are notably conservative (for example, 13-26% on single-family rentals), which is consistent with the desktop-scope tradeoff: lower cost and speed in exchange for less property-specific documentation than an on-site engineering engagement.
Model fit: Smaller, straightforward properties where a full engineering engagement does not pencil, and the owner accepts the documentation tradeoff of a remote study.
Provider logos are shown for identification only and remain the trademarks of their respective owners. Facts in each profile come from the provider's own site and can change; verify current scope and terms directly before engaging.
Why we do not recommend DIY cost segregation calculators
Free calculators (including ours) exist to answer one question: is a study worth pricing? Filing accelerated depreciation from a calculator output alone is a different act, and in our professional view a bad trade in both directions. Generic percentage estimates usually leave reclassifiable basis unclaimed, because they cannot see your property's actual components. And whatever they do claim rests on no engineering documentation, which is precisely what the IRS Cost Segregation Audit Techniques Guide says examiners evaluate, so the position carries more audit risk while delivering less deduction. Screen with a calculator; file with a study.
The four provider models behind the names
Pricing below is a market-planning range checked August 2026, not a Taxstra quote. Confirm current scope, travel, revisions, and support in writing.
| Provider model | Best fit | Inspection | Observed price tier | What to verify |
|---|---|---|---|---|
Full-service engineering firm | Complex commercial property, renovations, specialty systems, and larger portfolios | Usually on-site or a documented hybrid process | $4,000 to $25,000+ | Who performs the inspection, who signs the report, and exactly what audit support includes |
Engineer-reviewed residential specialist | Single-family rentals, duplexes, and smaller multifamily properties | Virtual, on-site, or hybrid depending on property and records | $2,000 to $4,500 | Whether the engineer reviews the property-specific work or only the final template |
Software-assisted or virtual study | Straightforward smaller rentals with complete records and photographs | Owner questionnaire, records, photographs, and remote review | $495 to $1,800 | Methodology, land allocation, property-specific assumptions, report signer, and escalation path |
CPA-firm bundled study | Investors who want the study and the tax return inside one engagement | Varies by firm; confirm who performs the engineering work | Custom quote | Whether engineering is performed in-house or subcontracted, and how the fee splits from tax work |
Use one scorecard for every proposal
Weight the report your tax team receives more heavily than the sales estimate. Ask each provider to respond against the same requirements.
Methodology
25%Property-specific engineering or cost-estimation method; no unsupported percentage shortcut
CPA-ready deliverable
25%Asset detail, class lives, conventions, basis reconciliation, and an importable schedule
Inspection and records
15%A process matched to property size, complexity, renovations, and available documentation
Audit-support terms
15%Named support, time limits, exclusions, and whether representation is included or separate
Tax-team coordination
10%Provider will answer the preparing CPA’s questions before the return is filed
Fee and fit
10%Fixed scope, disclosed add-ons, conservative benefit model, and a credible break-even case
What a CPA-ready report should include
- Property facts, placed-in-service date, and depreciable-basis reconciliation
- Land and building allocation method with source support
- Asset-by-asset classification, cost, recovery period, method, and convention
- Narrative explaining the engineering or cost-estimation methodology
- Photographs, plans, invoices, takeoffs, or cost-source support appropriate to the property
- A spreadsheet the return preparer can reconcile to the fixed-asset ledger
- Written process for questions, corrections, and examination support
“Audit defense” needs a definition
Ask who answers an examiner's questions, whether engineering staff participate, how many hours are included, how long support lasts, and whether travel, amended schedules, appeals, or representation cost extra. A marketing phrase is not the same as a contractual scope.
IRS Publication 5653 is an examiner-facing audit technique guide. It discusses study quality and methodologies, but following a guide does not make any report “audit-proof” or guarantee that every classification will be accepted.
The CPA handoff is part of the purchase
Buy a usable study, not a deduction headline
The report does not decide whether the deduction is currently usable. Your tax team still must address basis, timing, depreciation method, passive-activity and at-risk limits, state treatment, recapture planning, and whether an accounting-method change is required.
For property already depreciated under a different treatment, Form 3115 and a Section 481(a) adjustment may be part of the implementation. The correct filing path depends on the year and facts.
That implementation work happens inside a Taxstra tax engagement. Getting started begins with a free initial consultation.
Book a Free Initial ConsultationHave these ready for your tax team
- Provider proposal and engagement letter
- Feasibility estimate and assumptions
- Purchase closing statement and land allocation
- Renovation invoices and placed-in-service timeline
- Sample final report and spreadsheet
- Written support and revision terms
Frequently asked questions
What is the best cost segregation company?
There is no single best firm for every owner; the right provider depends on your property type, size, and how much documentation depth you need. Taxstra refers clients to Engineered Tax Services because their engineering-based studies cover every property type we plan for and hold up to the IRS documentation standard, but the profiles on this page cover residential specialists, remote providers, and CPA-firm models too. Compare deliverables against the same scorecard and do your own due diligence.
Should I use a free DIY cost segregation calculator instead of a study?
Calculators are useful for screening whether a study is worth pricing, and we publish one ourselves for exactly that purpose. But in our professional view a DIY calculator output is not a study: it typically leaves reclassifiable basis on the table, and claiming accelerated depreciation from an unsupported estimate increases audit risk because there is no engineering documentation behind the allocation. Use calculators to decide whether to buy a study, not as the study.
Does the IRS certify or rank cost segregation providers?
No. The IRS does not publish an approved-provider list. Publication 5653, the Cost Segregation Audit Techniques Guide, describes the methodologies and documentation examiners look for, which is why the quality of the report and its support matters more than any marketing claim.
How much does a cost segregation study cost?
Published market pricing runs from roughly $495 for remote software-driven residential reports to $25,000 or more for complex commercial engineering engagements, with engineer-reviewed residential studies commonly in the $2,000 to $4,500 range. These are observed market tiers as of August 2026, not Taxstra quotes; confirm scope, travel, revisions, and audit support in writing.
Can Taxstra implement a study from any of these providers?
Yes. Whichever firm performs the engineering, Taxstra can implement the accepted report on the return within a tax engagement, including Form 3115 and the Section 481(a) adjustment for look-back studies, and coordinate provider questions as part of that work.
Do I need Form 3115 for a cost segregation study?
A study performed after depreciation has already been established for prior tax years generally requires an accounting-method change and Form 3115, which claims the catch-up as a Section 481(a) adjustment with no amended returns. A study completed for a property in its first return year is applied directly. The preparing CPA should decide the filing path.