Aon vs 
USI Insurance Services: How Do They Compare for Professional Liability (E&O) Insurance?
Aon: professional liability as addressing professional-services firms’ liability exposure and says it tailors coverage structures to a firm’s needs. It identifies E&O as a commonly used name for professional-liability insurance; actual policy terms are not stated. USI Insurance Services: uSI describes the policy as insuring a CPA and their practice against third-party claims that professional services caused financial harm, providing a defense and paying damages for covered claims arising from high-risk situations tied to new clients, changing business plans, or new laws and regulations. 3,7
What Is Aon?
Aon’s U.S. Commercial Risk terms describe brokerage for certain insurance programs, while its Middle Market page describes a dedicated practice for mid-sized organizations across North America. The public materials reviewed do not identify the licensed producer or insurer for a particular placement. Ask which entity will produce each line and which insurer will issue the policy; request jurisdiction details for the proposed placement and ask how compensation and claim notice work for your account. 1,2
What Is USI Insurance Services?
USI suits software and hardware companies from seed stage through IPO seeking consultative broker support; buyers wanting a self-serve quote should compare digital agencies. Insurer commissions are typical and contingent compensation may also apply. 4,5,6
Read the USI Insurance Services profile
Read the USI Insurance Services Professional Liability (E&O) Insurance page
What Is Professional Errors and Omissions (E&O) Insurance?
Professional liability can help pay defense costs and covered losses when a client says your advice or service caused financial harm. If customers rely on your work, list every service you provide and check the claims-made reporting and prior-work terms. 10,11,12,13
What Are the Key Differences Between Aon and USI Insurance Services Professional Liability (E&O) Insurance?
Policy scope and stated allegations
Aon describes professional liability as addressing professional-services firms’ liability exposure and says it tailors coverage structures to a firm’s needs. It identifies E&O as a commonly used name for professional-liability insurance; actual policy terms are not stated. USI Insurance Services describes uSI describes the policy as insuring a CPA and their practice against third-party claims that professional services caused financial harm, providing a defense and paying damages for covered claims arising from high-risk situations tied to new clients, changing business plans, or new laws and regulations. Compare the specific allegations and covered costs in the forms rather than relying on a shared E&O label. 3 7
Who each practice serves
Aon identifies law, accounting and consulting firms as the audience for its global Professional Services Practice. That audience scope does not establish eligibility for every firm or other business. USI Insurance Services identifies uSI markets the AICPA program to sole practitioners and regional CPA firms. It has offered CPA coverage since 1967 and has been the endorsed AICPA Program provider since 1994. Check whether your profession and services fall within both descriptions, then ask underwriting to confirm eligibility. 3 7
Service after requesting a quote
Aon describes its professional-services advisors use industry knowledge, insights, data and tools to support risk-management and human-capital decisions. This is a company-described advisory service, not a claim outcome or policy benefit. USI Insurance Services describes uSI says firms enrolled in the program get supportive claims handling and exclusive access to risk-management resources, including engagement-letter templates, in addition to the coverage itself. Ask which team handles renewals, policy changes and claim questions for your E&O account. 3 7
What Should You Confirm in Aon and USI Insurance Services Professional Liability (E&O) Insurance Quotes?
- Ask Aon to confirm the quoted policy form, retroactive date and covered allegations; its offering says professional liability as addressing professional-services firms’ liability exposure and says it tailors coverage structures to a firm’s needs. It identifies E&O as a commonly used name for professional-liability insurance; actual policy terms are not stated. 3
- Ask USI Insurance Services to confirm the quoted policy form, retroactive date and covered allegations; its offering says uSI describes the policy as insuring a CPA and their practice against third-party claims that professional services caused financial harm, providing a defense and paying damages for covered claims arising from high-risk situations tied to new clients, changing business plans, or new laws and regulations. 7
Aon and USI Insurance Services Review Scores for 2026
These averages can combine ratings for different products, locations, and customer groups, including approximate BBB grade conversions. Read each review for the sources, scope, and calculation.
Aon Review Score
Review Score
3 rated sources
Public ratings for Aon are low: Trustpilot shows 1.2 out of 5 from 782 reviews, and BBB shows 1.6 from five. Aon is a global firm, so those pages mostly reflect other parts of the business, not large U.S. commercial accounts.[4][6][7]
Read Aon reviewsUSI Insurance Services Review Score
Review Score
1 rated source
USI’s public feedback is too sparse and office-specific for a firmwide verdict. Check the local team’s responsiveness and experience with your type of business.[4][6][8]
Read USI Insurance Services reviewsAon vs USI Insurance Services Professional Liability (E&O) Compared
Aon vs USI Insurance Services: Professional Liability (E&O) Insurance: documented features by provider
| Criteria | Aon Professional Liability / E&O brokerage and risk-advisory offering | AICPA Professional Liability Program (USI Affinity) |
|---|---|---|
| Role in This Line | Aon presents Professional Liability / E&O as a line its Professional Services Practice helps arrange or advise on for professional-service firms. Aon is describing a global brokerage and advisory service, not issuing the underlying policy. The producing legal entity and carrier for any particular placement are not named on this page. 3Company-reported. Aon’s global professional-services practice page. This establishes a marketed brokerage/advisory offering, not policy issuance or account-specific placement. | For CPA firms, USI runs the AICPA Professional Liability Program through its USI Affinity division as the endorsed producer, rather than underwriting the policy itself. USI's general Business Services practice separately brokers errors and omissions/professional liability coverage for other business types. 7,9Company-reported. AICPA program page and Business Services practice page. |
| Issuing Insurer | The reviewed practice page does not name the insurer or producing legal entity for a specific placement. Ask for both on the quote and binder. 3Not found in reviewed sources. Aon’s global practice page as reviewed 2026-09-30; no state-specific placement schedule or buyer quote was reviewed. This does not establish that Aon cannot arrange a placement. | USI's own page states that the AICPA Professional Liability Program is "underwritten by CNA," naming the carrier for that specific program. USI's general Business Services E&O placements do not name an insurer. 7Company-reported. Direct quote from the AICPA program page; CNA underwrites only this named program, not USI's other professional-liability placements. |
| Who It’s For | Aon identifies law, accounting and consulting firms as the audience for its global Professional Services Practice. That audience scope does not establish eligibility for every firm or other business. 3Company-reported. Audience described for Aon’s global professional-services practice. It does not establish U.S. state availability or underwriting eligibility for a placement. | USI markets the AICPA program to sole practitioners and regional CPA firms. It has offered CPA coverage since 1967 and has been the endorsed AICPA Program provider since 1994. 7Company-reported. Program page description. |
| Coverage Features | Aon describes professional liability as addressing professional-services firms’ liability exposure and says it tailors coverage structures to a firm’s needs. It identifies E&O as a commonly used name for professional-liability insurance; actual policy terms are not stated. 3Company-reported. Aon’s marketing description of the brokerage/coverage area. The page is not the insurer’s policy form and does not establish an insured's entitlement to coverage. | USI describes the policy as insuring a CPA and their practice against third-party claims that professional services caused financial harm, providing a defense and paying damages for covered claims arising from high-risk situations tied to new clients, changing business plans, or new laws and regulations. 7Company-reported. Program page description; actual insuring agreements, exclusions and conditions are set by the issued CNA policy form. |
| Limits and Retentions | The reviewed page does not state a buyer-specific limit, retention, deductible or other placement terms. Confirm these in the quote, bond or issued policy. 3Not publicly disclosed. Aon’s global practice page as reviewed 2026-09-30; no quote, bond form or issued policy was reviewed. | The AICPA program page does not publish limit, retention or premium figures; it says coverage plans allow a firm to tailor coverage to its risk profile. 7Not publicly disclosed. Page as read on 2026-09-23. |
| Risk Services | Aon says its professional-services advisors use industry knowledge, insights, data and tools to support risk-management and human-capital decisions. This is a company-described advisory service, not a claim outcome or policy benefit. 3Company-reported. Company-reported advisory services on Aon’s global practice page; account-specific service scope is not stated. | USI says firms enrolled in the program get supportive claims handling and exclusive access to risk-management resources, including engagement-letter templates, in addition to the coverage itself. 7Company-reported. Program page description. |
| How to Apply | Confirm in your quote. | USI directs CPA firms seeking a quote or renewal to contact USI Affinity, with a dedicated Affinity_APL@usi.com address for the AICPA program specifically. 7Company-reported. Contact instructions on the AICPA program page. |
Related Pages for Aon vs USI Insurance Services
Professional Liability (E&O) Pages for Aon and USI Insurance Services
Other Coverage Lines Compared for Aon vs USI Insurance Services
Other Professional Liability (E&O) Insurance Provider Comparisons
Sources for Aon vs USI Insurance Services
Sources About Aon
- Commercial Risk Solutions U.S. Brokerage Terms of Service. Aon; Lines 120–127: certain-program broker-of-record scope, consultation, application assistance, client signature and bind instruction, and account administration; lines 140–147: variable and contingent compensation, potential placement incentive, and client request route; lines 206–213: no price guarantee and surplus-lines limitations; lines 229–231: client insurer-notice duty unless separately agreed. Accessed 2026-09-29.
- Middle Market Clients. Aon; Lines 125–132: mid-sized organizations and middle-market framing; lines 165–173: dedicated practice and North America statement; lines 188–224: Commercial Risk capabilities. No numeric company-size cutoff or U.S.-only eligibility rule is stated on the reviewed page. Accessed 2026-09-29.
- Professional Services Practice. Aon; Named professional-services audiences and global advisory role, lines 125–128; line offerings and explanations lines 131–190; contact link lines 120–122. Global practice page; no U.S. state or account-specific placement schedule. Accessed 2026-09-30.
Sources About USI Insurance Services
- The Power of ONE. USI Insurance Services; History, client-count, nationwide office, and P&C / benefits / personal risk / retirement description. Accessed 2026-09-16.
- Technology Insurance. USI Insurance Services; Technology practice client types, seed-to-IPO range, and listed insurance placement lines including PrivaSafe. Accessed 2026-09-16.
- Commissions and Fees. USI Insurance Services; Licensed-producer authority, insurer-paid commission default, contingent compensation, and client request right. Accessed 2026-09-16.
- Accountants Professional Liability — USI Affinity. USI Insurance Services; Quality Professional Liability Insurance Exclusively for CPA Firms; "The AICPA Professional Liability Program, underwritten by CNA, has been offering coverage to CPAs since 1967 and has been the endorsed provider of the AICPA Program since 1994."; supportive claims handling and exclusive access to extensive risk management resources, including engagement letter templates; Email Affinity_APL@usi.com. Accessed 2026-09-23.
- USI Specialty Program Solutions. USI Insurance Services; USI Affinity delivers high-quality insurance and financial solutions to members of affinity organizations and targeted industry segments...for professional associations, law firms, alumni and collegiate organizations, travel groups, and insurance administrators. Accessed 2026-09-23.
- Business Services. USI Insurance Services; USI advises clients...and provides solutions for...Errors & Omissions/Professional Liability... Accessed 2026-09-23.
Sources for the Professional Liability (E&O) Insurance Guide
- FAQ: Professional liability insurance. Texas Department of Insurance; What’s professional liability coverage?; What types of damages…; What’s general liability insurance?; Do I need professional liability… if I have general liability…?; Is professional liability insurance required?; Can a client require…?; What’s the difference between occurrence policies and claims-made policies. Accessed 2026-09-16.
- Professional liability insurance. Insurance Information Institute; Opening paragraphs (professional services/advice and E&O name); Claims not covered by general liability; What types of businesses need professional liability insurance?; What’s covered… and what’s not (claims-made versus occurrence, defense and judgments, non-financial/intentional limits, BOP/in-home exclusion). Accessed 2026-09-16.
- Get business insurance. U.S. Small Business Administration; Six common types of business insurance table. Accessed 2026-09-16.
- Professional Liability – US Direct Errors and Omissions Insurance. Hiscox Inc. specimen; About this Policy / Coverage for Claims Made Against You; I.A Insuring Agreement; I.B Defense; I.C Settlement; II.A Notice of Claims; II.C Optional Extended Reporting Period; III.A, III.K, III.M, III.R, III.S Exclusions; IV.A–B Limits and Deductible; VI.O Professional Services; VI.U Wrongful Act. Accessed 2026-09-16.
