Top Cost Segregation Firms With CPA Partner Programs In 2027

Last updated: November 12, 2026

The best cost segregation firms with CPA partner programs in 2027 are Engineered Tax Services, Cost Seg Smart and R.E. Cost Seg, followed by McGuire Sponsel, Capstan Tax Strategies and Duffy+Duffy. Engineered Tax Services leads for the largest formal CPA program, Cost Seg Smart for clear referral fees and white-label pricing, and R.E. Cost Seg for an advisor portal built around investor clients.

For a CPA firm, a cost segregation partner should make the firm look good. That means studies that hold up, delivery before filing deadlines, clear Form 3115 support, and a partner that does not try to take over the client relationship. The One Big Beautiful Bill Act made 100% bonus depreciation permanent for qualifying property acquired after January 19, 2025, so reclassified components can often be deducted in the first year on the federal return.

This list is for CPA firms, enrolled agents and tax advisors. For clients who need full planning, see our list of real estate CPA firms.

CPA Partner Program Cost Segregation Firms At A Glance

Firm	Location	Founded	Specialty	Best For
1. Engineered Tax Services	West Palm Beach, FL	2001	Licensed engineering firm for specialty tax	CPA firms of any size
2. Cost Seg Smart	Los Angeles, CA	2024	Residential and commercial studies with audit support	Firms with investor clients
3. R.E. Cost Seg	Houston, TX	2022	Investor-focused studies at two depths	Firms serving investors
4. McGuire Sponsel	Indianapolis, IN	2007	Specialty tax partner to CPA firms	Firms that keep the client relationship
5. Capstan Tax Strategies	Jenkintown, PA	2015	Engineering-driven specialty tax for CRE	Commercial real estate practices
6. Duffy+Duffy	Westlake, OH (Novi, MI office)	2002	Cost segregation only	Firms that want CPE
7. KBKG	Pasadena, CA (seven US offices)	1999	Tax credits and incentives with engineered studies	Larger accounting firms
8. CSSI	Baton Rouge, LA	Not published	Engineering-based cost segregation only	Firms with commercial clients
9. Source Advisors	Arlington, TX	Not published	Cost segregation and fixed asset studies	Firms that want site visits
10. CSA Partners	Lindon, UT	Not published	Cost segregation only	Western firms

How We Evaluated These Firms

We looked for firms with a published partner, referral or white-label program, CPE or training for partner firms, and a track record of working alongside rather than around the client’s accountant. We also weighed audit support and the ability to deliver before extended deadlines.

Rankings are editorial. No firm paid for its position.

Best Cost Segregation Firms With CPA Partner Programs In 2027

1. Engineered Tax Services — The Largest Formal CPA Partner Program

Engineered Tax Services says it works with more than 500 CPA partner firms and reports a 95% client retention rate. It offers white-label, referral and sub-affiliate arrangements.

Its licensed engineers also handle 179D, 45L and R&D work, so partner firms can offer several incentives through one relationship.

Best for: CPA firms that want a full menu of specialty tax services from one partner.

2. Cost Seg Smart — Clear Referral Fees And White-Label Pricing

Cost Seg Smart publishes its CPA program terms: referral fees of $200 for residential and $400 for commercial studies, or a white-label option at a 20% wholesale discount. Audit support is included.

Its residential focus suits firms with many short-term and long-term rental clients.

Best for: CPA firms with many rental investor clients who want transparent terms.

3. R.E. Cost Seg — An Advisor Portal And Affiliate Program

R.E. Cost Seg runs an advisor portal and affiliate program, and offers both a Rapid Report and a Fully Engineered Study so the accountant can match the depth to the client.

Audit support is included.

Best for: CPA firms that want a portal to track client studies.

4. McGuire Sponsel — Built To Work Through The CPA

McGuire Sponsel positions itself as a partner to CPA firms, with engineers, accountants and consultants who conduct on-site inspections and support the CPA’s return.

It also handles other specialty tax incentives, which keeps the CPA as the client’s main advisor.

Best for: CPA firms that want a specialist partner that never competes for the client.

5. Capstan Tax Strategies — A Referral Partner For CRE-Focused Firms

Capstan Tax Strategies works as a referral partner for CPAs and publishes guidance on tangible property regulations, partial asset dispositions and qualified improvement property.

Its partners have completed more than 8,000 studies.

Best for: CPA firms with commercial real estate clients.

6. Duffy+Duffy — Free CPE Seminars And Flat-Fee Quotes

Duffy+Duffy runs a referral partnership for accounting firms and offers free CPE seminars in several states, including Ohio, Michigan, Pennsylvania and South Carolina.

It gives a flat-fee quote and an estimate of benefits before work begins.

Best for: CPA firms that want training for their staff.

7. KBKG — Technical Depth Accountants Trust

KBKG is widely used by accounting firms for depreciation, fixed asset and tangible property work, and it publishes technical tools and guidance used by practitioners.

It has offered cost segregation since 1999.

Best for: Larger accounting firms that want deep technical support.

8. CSSI — Scale And A Long CPA Track Record

CSSI has completed more than 20,000 studies and works closely with CPAs nationwide, with regional representatives in several states.

It suits firms with a steady flow of commercial clients.

Best for: CPA firms with steady commercial volume.

9. Source Advisors — Specialty Tax Depth With Site Visits

Source Advisors brings more than 40 years of specialty tax experience, works alongside clients’ CPAs, and conducts a site visit on nearly every study.

It also offers R&D and energy incentive work.

Best for: CPA firms whose clients expect an engineer on site.

10. CSA Partners — A Specialist That Stays In Its Lane

CSA Partners focuses only on cost segregation and runs a national engineering network from Lindon, Utah.

Its single focus suits firms that want a partner with no other services to sell.

Best for: CPA firms that want a cost segregation specialist only.

How To Choose A Cost Segregation Partner For Your CPA Firm

Referral, White-Label Or Co-Delivery?

Decide whether you want a fee, your own branding, or a joint engagement. Programs differ widely.

Will The Partner Respect The Client Relationship?

Ask how the partner communicates with clients and whether it sells other services directly.

Can It Meet Extended Deadlines?

Ask for turnaround guarantees for September and October filings.

Is Audit Support Included?

Your firm’s reputation rides on the study. Confirm audit support.

Does It Offer CPE Or Training?

Training helps your staff spot good candidates.

Frequently Asked Questions

Can a CPA firm white-label a cost segregation study?

Yes. Several firms, including Engineered Tax Services and Cost Seg Smart, offer white-label arrangements.

Do referral fees create independence issues?

They can for attest clients. Check your firm’s independence rules and disclosure requirements before accepting fees.

Who files Form 3115 for a lookback study?

The client’s CPA usually files it, with support from the cost segregation firm.

What clients make good candidates?

Clients with recent purchases, renovations or new construction, usually over a few hundred thousand dollars in building basis.

Conclusion

Engineered Tax Services, Cost Seg Smart and R.E. Cost Seg are the strongest partners for CPA firms, with McGuire Sponsel, Capstan and Duffy+Duffy suited to firms that want a specialist that stays behind the CPA.

For related lists, see our real estate CPA firms, cost segregation firms with audit defense guarantees and cost segregation firms for lookback studies.