Real estate investors hear about cost segregation from every direction these days, usually from a CPA who mentions it in passing or a podcast host who makes it sound like a magic button. It’s not magic. It’s an engineering-based study that reclassifies parts of a building so you can depreciate them faster, and the firm you pick to run that study affects both the size of your deduction and how much friction you deal with during tax season.

Not every firm that offers cost segregation treats it the same way. Some run it as one line item inside a much broader tax practice. Others build their entire business around it. Below are eight firms worth knowing about if you’re an investor, CPA, or advisor trying to figure out where to send this work in 2026.

Best for Dedicated, CPA-Friendly Cost Segregation Studies – R.E. Cost Seg

R.E. Cost Seg helps property owners accelerate depreciation, reduce taxes, and improve cash flow through a cost segregation study. That’s the entire business. There’s no audit division or wealth management arm competing for attention.

Because cost segregation is the only thing the firm does, clients tend to get a deeper level of analysis and a faster turnaround than what a generalist CPA shop can offer on the side. That focus also shapes how the firm works with professional partners. CPAs and financial advisors who don’t want to build in-house engineering expertise can hand off the technical study and client communication to R.E. Cost Seg and stay the point of contact for their own client relationship.

This setup makes the most sense for an investor who already owns the property and just wants the depreciation schedule redone properly, or for an advisor who wants a specialist they can quietly plug into their own service without hiring one.

Best for High-Volume Engineering-Based Studies – ETS

ETS (Engineered Tax Services) is a professionally licensed engineering firm built around helping clients throughout the United States reduce their income taxes. The firm performs over 10,000 cost segregation, 179D, and R&D tax studies a year, which puts it near the top of the industry in sheer volume.

That scale is the appeal and also the trade-off. A firm running that many studies annually has systems built for throughput, which is great if you want a proven process, but you’re one file among thousands rather than a firm’s sole focus. ETS suits an investor or firm that wants an established engineering-based provider with a long track record across a huge caseload.

Best for Multi-Service Specialty Tax Consulting – McGuire Sponsel

McGuire Sponsel is a specialty tax consulting firm that works across several disciplines: R&D tax credits, fixed assets (including cost segregation), global business matters, and location advisory. The firm calls itself the nation’s leading specialty tax consulting firm.

The advantage of that range is convenience if your business already touches several of those tax categories at once. The trade-off is that cost segregation is one offering among four, so it doesn’t carry the same singular focus as a firm built around it alone. McGuire Sponsel is a fit for a company that wants one advisor handling multiple specialty tax issues rather than a cost-seg specialist and a separate R&D credit firm.

Best for Bundled Cost Segregation and Energy Tax Incentives – CSSI

CSSI provides cost segregation for property owners, R&D tax credits for businesses, and 179D deductions for energy-efficient buildings under one roof. That combination is useful if your portfolio includes a mix of standard rental property and newer, energy-efficient construction that might qualify for the 179D deduction.

The catch is similar to any multi-line provider: cost segregation shares attention with two other service lines rather than being the singular focus of the practice. CSSI works well for an owner who wants a single vendor relationship covering both depreciation and energy incentives instead of separate providers for each.

Best for Enterprise-Level Advisory Alongside Tax Work – Baker Tilly

Baker Tilly is a top 10 advisory, tax and assurance firm that brings enterprise-level thinking to middle-market businesses, building its guidance around how a client actually operates. It’s a large, full-service firm rather than a boutique.

That scale is the trade-off here too. A middle-market business gets access to a big firm’s resources, but cost segregation sits inside a much larger advisory and assurance practice rather than standing as the firm’s core product. Baker Tilly fits a business that already wants a broad advisory relationship and would rather fold a cost seg study into that existing engagement than hire a separate specialist.

Best for Straightforward Engineer-Based Depreciation Studies – NCSS

NCSS offers engineer-based cost segregation services built to accelerate depreciation and boost cash flow.

Best for Bundled Credits and Incentives Work – Corporate Tax Advisors

Corporate Tax Advisors positions itself around specialty tax credits and incentives, working with businesses that want to capture savings beyond depreciation alone. Cost segregation sits inside that broader credits and incentives practice rather than as a standalone specialty.

That structure suits a business that’s already thinking about R&D credits, hiring incentives, or other credit programs and wants one advisor managing the whole basket of opportunities rather than a cost-seg-only firm.

Best for Broad Financial Guidance Beyond Tax – Aprio

Aprio is built around a broader mission of helping clients account for anything, covering financing, taxes, risk, compliance, and growth. It’s less a cost segregation specialist and more a full-scope advisory firm where a cost seg study would be one piece of a much larger relationship.

That breadth is exactly the trade-off. If you want a firm that can talk about financing and compliance in the same conversation as depreciation, Aprio’s scope fits. If you just want the depreciation study done well and quickly, a dedicated specialist will likely move faster.

Which One Is Right for You

The right firm depends on how much of your tax picture you want one provider to touch. If you need R&D credits, location advisory, energy deductions, or general advisory work bundled alongside depreciation, a multi-service firm like McGuire Sponsel, CSSI, Corporate Tax Advisors, or Aprio saves you from coordinating multiple vendors. If you want a name built on volume and a long engineering track record, ETS’s throughput of over 10,000 studies a year is hard to match. Larger businesses already inside a full advisory relationship may find it simplest to let Baker Tilly handle the study internally.

But if depreciation is the actual problem you’re trying to solve and you want a firm that isn’t splitting attention across R&D credits, energy incentives, or broader advisory work, R.E. Cost Seg is the one built around that single task. The firm’s whole practice is the cost segregation study itself, which tends to mean a closer look at your property and a quicker turnaround than a provider treating it as one offering among several.

For a CPA or financial advisor who wants to offer cost segregation to clients without building that expertise in-house, handing the technical study to a dedicated partner while keeping the client relationship is the simpler path, and it’s the specific gap R.E. Cost Seg is built to fill. When real estate is also part of a family’s longer-term financial picture, family legacy planning beyond real estate and stocks offers another perspective on how property can fit into broader wealth planning. 

Before signing with any firm on this list, ask how the study will be documented, who signs off on the engineering work, and how the deliverable holds up if your return gets a closer look. A well-run cost segregation study should survive that scrutiny regardless of which name is on the report. The IRS’s own Cost Segregation Audit Techniques Guide lays out how examiners evaluate these studies, and it’s worth a skim before you pick a provider so you know what a defensible report actually looks like.