Duffy + Duffy Review (2026)

Pricing, methodology, audit defense, and where this provider fits.

Editorial note: Cost Segregation Reviews is operated by Cost Seg Smart, which appears as one option among many on this site, including in this review. Public-facing data only — pricing, methodology, and credentials reflect what Duffy + Duffy publishes on its own site. Reviewed September 2026.

All engineering-based cost segregation studies — Duffy + Duffy's included — follow the same federal framework: MACRS classification under Rev. Proc. 87-56, the §1245 personal-property and §1250 land-improvement categories carved out of a building's cost basis, and the documentation standard set by the IRS Cost Segregation Audit Techniques Guide (Pub 5653). Duffy + Duffy is a Westlake, Ohio-based boutique that specializes in commercial and LEED-certified construction, pairing CPAs with construction engineers and estimators. Its site publishes no pricing, turnaround estimate, site-visit policy, or written guarantee — a quote follows a no-cost estimate. Cost Seg Smart, one of the other options on this site, publishes a fixed $495 starting price for residential properties under $300,000 rather than a quote-on-request model.

Pricing detail

Not published. Duffy + Duffy's site offers a “no-cost estimate of potential tax deferrals,” with a fee quote following that estimate — there is no published rate card or price range.

Pricing reflects what the firm publishes as of September 2026. A quote-on-request model is common among boutique commercial firms and, on its own, says nothing about whether the eventual fee runs high or low relative to peers. For context on typical rates, see our guide to how much a cost segregation study should cost.

Methodology and process

Duffy + Duffy describes its work as an “Engineering-based Cost Segregation Study,” which its site states is “the only method recognized by the IRS to identify Personal Property and Land Improvements contained in a commercial structure,” performed using CPAs, construction engineers, and estimators. That description tracks the documentation standard the IRS Cost Segregation Audit Techniques Guide sets for engineering-based studies generally. The firm's site separately states it “conducts Cost Segregation on LEED Certified Construction Projects” specifically, and its About page cites a 2023 “Top-5 Cost Segregation Firm” recognition from Realty Street — a third-party ranking, not an IRS or professional-body designation.

Property-type fit

Duffy + Duffy's site is built around commercial buildings, with a named specialization in LEED-certified construction, and states it serves builders, developers, investors, and franchisees. It does not present single-family rental, short-term rental, or small multifamily as target categories. For those, see our STR-focused and single-family rental rankings.

Audit defense

Audit-defense terms — a stated guarantee, follow-up support, or IRS-representation scope — are not published on Duffy + Duffy's current site. The firm's methodology claim (engineering-based, using CPAs and construction engineers) tracks what the IRS Cost Segregation Audit Techniques Guide expects of a study's documentation, but that description is not itself a stated defense policy.

Pros

• Specializes in LEED-certified commercial construction — a niche most generalist providers don't call out by name.
• Offers a no-cost estimate of potential tax deferrals before a client commits to a paid engagement.
• Uses a combination of CPAs and construction engineers/estimators, consistent with an engineering-based approach.

Cons

• Pricing is not published anywhere on the current site.
• The firm's original domain (duffycostseg.com) no longer resolves; it now operates at costsegexperts.com under the name Duffy+Duffy Cost Segregation Experts, which could confuse investors searching by the old name.
• Turnaround time, site-visit policy, and audit-defense terms are not published.

Verdict — who this is for

Duffy + Duffy fits commercial property owners, developers, and franchisees with LEED-certified or sizable commercial projects who want a boutique firm pairing CPAs with construction engineers, and who are comfortable requesting a quote rather than seeing a rate card up front. It is not positioned for small residential or short-term-rental investors. For those, see the full 27-provider comparison.

FAQ

Sources

• https://costsegexperts.com/about.cfm
• https://costsegexperts.com/core-values.cfm

Accessed 2026-09-06.

Pricing and operational details reflect public information as of September 2026. Provider corrections welcome via the submission form. This review is not legal, tax, or financial advice — confirm cost segregation suitability with your CPA before ordering a study.