Cost Segregation Companies Compared: Which Model Fits Your Property

Why "best" is the wrong first question

Every firm on this page runs the same underlying mechanics: reclassifying parts of a building, carpet, cabinetry, decorative lighting, parking lot paving, site lighting, out of the standard 39-year (commercial) or 27.5-year (residential rental) depreciation schedule and into 5-, 7-, or 15-year buckets. The reclassified basis becomes bonus-eligible in the year the study is delivered. That part of the process does not vary much by firm, because it follows the same IRS Audit Techniques Guide (Pub 5653) regardless of who performs it.

What varies is who each firm is built to serve. A Big Four practice sized for a REIT's hundred-property portfolio and a shop built to classify a single short-term rental from listing photos are solving different problems, even though both call the output a "cost segregation study." Comparing them on price alone misses the point. The real question is which model matches your property and your situation.

Why this is a real industry, not a gray-area tactic

It helps to start with why so many firms exist to do this work at all. Depreciation reclassification through cost segregation has been settled law since the IRS lost Hospital Corporation of America v. Commissioner (109 T.C. 21, 1997). Rather than fighting the practice, the IRS instead publishes its own Audit Techniques Guide (Pub 5653) describing what a proper study looks like. Every firm on this page, regardless of size or model, is working from that same playbook. None of them are exploiting a loophole; they are following a documented, IRS-endorsed methodology and competing on how they deliver it.

That context matters for comparison shopping. The firms below do not differ on whether the underlying tax position is legitimate. They differ on client size, process, fee structure, and which owner they are built to serve well.

Big Four advisory practices: Deloitte and KPMG

Deloitte and KPMG are two of the Big Four global professional services firms, and both run tax practices that include cost segregation and fixed-asset depreciation work. Neither markets cost segregation as a standalone consumer-facing service the way a specialty firm does; the work sits inside a broader corporate tax and advisory practice built around large enterprise clients, industries like financial services, government, life sciences, and industrial manufacturing. That is a real strength for a REIT, a private equity real estate fund, or a corporation with a large owned-property portfolio that already has a relationship with the firm for audit or broader tax advisory work. The engagement can be coordinated with existing audit and advisory work, and the firm's institutional scale means it has almost certainly handled a portfolio's specific property types before, whatever they are.

For a single commercial building or a short-term rental, that same structure is often a poor fit. Engagement minimums, timelines, and reporting built for institutional-scale portfolios do not bend easily for a $2M warehouse or a beach house. An owner without an existing enterprise relationship is also, practically speaking, approaching a firm not structured to sell a single, self-contained engagement quickly. See the fuller comparison with Deloitte and the KPMG comparison for how the service models diverge in practice.

National specialty tax firms: KBKG, CSSI, Engineered Tax Services, Madison SPECS, Cost Segregation Authority

This is the largest and most established tier. KBKG is a large, decades-old specialty tax firm with broad service lines beyond cost segregation, including R&D tax credits, 179D, and 45L, serving property owners across many industries. CSSI (Cost Segregation Services) has run for more than two decades and reports having completed over 65,000 studies, working through a network that includes CPAs and tax professionals as well as direct real estate investor clients. Engineered Tax Services runs a similar broad specialty-tax model, cost segregation alongside R&D credits, 179D, 1031 exchange support, and CPA firm partnerships. Madison SPECS is a national cost segregation firm headquartered in New Jersey with engineers and CPAs working nationwide, focused specifically on cost segregation rather than a wider tax-credit portfolio. Cost Segregation Authority now operates as CSA Partners, a nationwide engineering-based firm reporting more than 30,000 completed studies, serving CPAs, developers, and investors.

These firms share real strengths: engineering-based methodology, decades of institutional knowledge, and enough volume to have seen nearly every property type. Working through a CPA's existing referral relationship, as CSSI's network model and several others do, can also simplify the decision for an owner whose CPA already vouches for a specific firm. They are a solid fit for a commercial owner who wants a well-established name and does not mind a fee structure and process built primarily around commercial property rather than one tuned specifically to short-term rentals. See the KBKG comparison and the CSSI comparison for the specific fit contrasts.

STR-focused and self-serve tools: RE Cost Seg, Remote Cost Seg, DIY calculators

A newer tier has grown up specifically around the short-term rental and smaller residential market, leaning on remote and virtual processes rather than site visits. RE Cost Seg offers engineered studies alongside a faster "rapid report" option and Form 3115 preparation help, with a fully virtual process and its own savings calculator as an entry point. Remote Cost Seg markets itself around speed and a fully virtual study taking under an hour of the owner's time, with an online calculator estimating potential savings before any commitment; its public materials describe a specific average client savings figure as part of that marketing, a claim worth verifying against your own property rather than assuming it applies broadly. Several firms, including KBKG, also publish standalone residential cost segregation calculators as a self-serve entry point for owners who want a rough number without a full engagement yet.

These tools are genuinely useful for what they are built for: fast, low-friction entry for smaller residential property, particularly single-family rentals and vacation properties. The tradeoff is usually depth. A calculator-driven estimate is not the same as a full engineering-based study with asset-by-asset documentation, and virtual-first firms vary in how much of their deliverable is a full engineered report versus a lighter-weight report tier. Someone comparing across this tier should ask each firm directly whether the "rapid" or virtual option is a full engineered report at smaller scope, or a lighter-weight summary, since the two are not interchangeable when a study later faces exam.

The broker model: where Basis fits

Basis runs a fourth model: a broker structure that sources engineered fulfillment (our engineering team, including work from one of the largest accounting firms in the country) while building the owner-facing process specifically around short-term rental and individual commercial owners rather than institutional portfolios. That shows up in four specific ways. First, STR studies run photos-only, classifying components from the same listing photos already on Airbnb or VRBO, no site visit. Second, a free Preliminary Benefit Estimate models the likely first-year number before any commitment, through the 60-second qualifier at /qualify. Third, every study carries a guarantee, at least 20 times the fee in first-year deductions on commercial property or 30 times on a short-term rental, or the study is free. Fourth, both a budget engineered tier and a full engineered tier are available, and both deliver the same 70-page IRS Audit Techniques Guide aligned report.

Fit by owner type

What actually differs once you look past the model

Four things separate firms within any tier: fee structure (custom-priced to the property versus a flat rate card), whether the process requires a site visit, what happens if the study underperforms, and turnaround. A study typically takes 4 to 6 weeks in peak tax season and 2 to 3 weeks in January and February across most engineering-based firms, so speed claims should be read against that baseline. The specific questions worth asking any firm on this page cut through marketing language faster than comparing logos.

Fee structure deserves its own note. Every legitimate engineering-based study, at any firm, is priced to the specific property rather than off a public rate card, because the engineering scope scales with building size and complexity. A firm quoting one flat number regardless of property size is not pricing the actual work involved. What differs across firms is the guarantee, if any, attached to that fee. Basis pairs its custom pricing with a floor: at least 20 times the fee in first-year deductions on commercial property, or 30 times on a short-term rental, or the study is free. Ask any firm on this page whether a comparable floor exists on its own engagements.

Audit defense is the other place firms diverge quietly. "Full audit defense" should mean the team that built the report defends the report itself if an examiner raises questions, not a vague promise of "support." That is different from representing the taxpayer overall, which stays the client's own CPA's job regardless of which firm performed the study. Confirming exactly what a firm's audit defense covers, before signing anything, avoids a surprise later.

How to use this comparison

Start with property type. An institutional portfolio belongs with a Big Four or large specialty firm relationship that already exists. A single commercial building fits a national specialty firm or the broker model, depending on whether a photos-only STR process or a guarantee matters more than brand tenure. A short-term rental fits an STR-focused firm almost by default, whether that is a virtual-first competitor or Basis's photos-only process. A free estimate, whichever firm provides it, is the lowest-risk way to see whether a full engagement is worth pursuing before paying anything.

The individual comparison pages linked throughout this hub go deeper on each specific firm, covering what each one is built for, where it genuinely outperforms a narrower model, and where the fit breaks down for a given property type. None of them are written to declare a single winner across every situation, because there isn't one. The winner is whichever model matches the property in front of you.

Details about each competitor above come from its public materials as of August 2026; tell us if something is out of date.

Every guide in this series

Frequently asked questions

Is a Big Four firm ever the right choice for a single rental property?

Rarely. Big Four practices like Deloitte and KPMG are built around institutional portfolios and corporate tax departments, with engagement structures that do not typically scale down to a single commercial building or short-term rental efficiently.

What's the real difference between an engineered study and a DIY calculator?

An engineered study documents every reclassified component individually with supporting cost data, built to survive an IRS examiner's questions. A DIY calculator produces a fast estimate based on general assumptions, useful for a first look but not a substitute for the documentation a full study provides.

Do national specialty firms and broker-model firms use different depreciation rules?

No. The underlying classification rules, the 5-, 7-, 15-, and 39/27.5-year buckets, and the IRS Audit Techniques Guide apply the same way regardless of which firm performs the study. What differs is process, fee structure, and which property types the firm is built to serve.

Why do some firms offer a free estimate and others don't?

A free estimate requires a firm to be confident enough in its own modeling to show a number before payment. Firms built around larger enterprise engagements often skip this step because their sales process assumes a longer relationship-based sale rather than a self-serve first look.

How current is the competitor information on this page?

It reflects each firm's public materials as of August 2026. Firms update their services and positioning over time, so if something here looks out of date, that is worth flagging.