Aon vs Marsh Mclennan Agency: Professional Liability / E&O Insurance

Areas of coverage

Aon

role: 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. Aon’s global professional-services practice page. This establishes a marketed brokerage/advisory offering, not policy issuance or account-specific placement.company-reportedSource ↗
eligibility: 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. Audience described for Aon’s global professional-services practice. It does not establish U.S. state availability or underwriting eligibility for a placement.company-reportedSource ↗
coverage: 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. 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.company-reportedSource ↗
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. Company-reported advisory services on Aon’s global practice page; account-specific service scope is not stated.company-reportedSource ↗
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. 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.not-foundSource ↗
limits: 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. Aon’s global practice page as reviewed 2026-09-30; no quote, bond form or issued policy was reviewed.not-disclosedSource ↗

Marsh McLennan Agency

role: Marsh McLennan Agency describes arranging professional errors omissions for the audience stated on the cited product page. professional errors omissions marketed by marsh-mclennan-agency; scope is limited to the cited official product overview and described audience. This is not a policy form or a universal eligibility statement.company-reportedSource ↗
eligibility: Organizations seeking professional liability placement; source does not imply all professions share one policy. professional errors omissions marketed by marsh-mclennan-agency; scope is limited to the cited official product overview and described audience. This is not a policy form or a universal eligibility statement.company-reportedSource ↗
coverage: The cited product page describes E&O and named specialist professional lines, including architects and engineers and lawyers professional liability; the overview does not treat them as one form. Marketing description only; actual coverage, exclusions, conditions, limits, and availability depend on the issued policy and jurisdiction. professional errors omissions marketed by marsh-mclennan-agency; scope is limited to the cited official product overview and described audience. This is not a policy form or a universal eligibility statement.company-reportedSource ↗
application: The page invites organizations to contact a Marsh McLennan Agency adviser or specialist to discuss placement. The page does not establish a quote, bind, or coverage-effective timeline. professional errors omissions marketed by marsh-mclennan-agency; scope is limited to the cited official product overview and described audience. This is not a policy form or a universal eligibility statement.company-reportedSource ↗
limits: The cited overview does not set a universal limit or retention for this line. Ask for the proposed policy form, limits, retentions, exclusions, and conditions in the quote. Only the cited marketing page was reviewed for published limit and retention information; no policy-form entitlement is inferred.not-disclosedSource ↗

What Are the Key Differences Between Aon and Marsh McLennan Agency Professional Liability (E&O) Insurance?

Professional Class and Product Scope

Aon describes professional liability as coverage tailored to a firm’s needs and names law, accounting and consulting among the firms served. Marsh McLennan Agency lists E&O and specialist lines such as architects-and-engineers and lawyers professional liability, while clarifying that the overview does not treat them as one form. A buyer should identify the correct occupational product rather than assume a general E&O policy covers licensed work; ask each provider how the insured-services definition is written. [1] [4]

Placement Detail and Buyer Decisions

Marsh McLennan Agency invites organizations to discuss placement with an adviser or specialist but does not set a universal limit or retention. Aon also describes advisor-led brokerage and does not publish policy terms or identify the carrier for a particular placement. The route is consultative in both cases, so compare the actual proposed form, not the product labels. Request the insurer, exclusions, limits and retroactive date for the policy matched to your profession. [1] [4]

What Should You Confirm in Aon and Marsh McLennan Agency Professional Liability (E&O) Insurance Quotes?

Ask Marsh McLennan Agency whether your profession needs its named specialist form and request its terms and limits. [1] [4]
Ask Aon which carrier and professional-services definition it proposes for your work. [1] [4]

Aon describes tailored professional-liability structures for professional firms. Marsh McLennan Agency lists E&O alongside architect-engineer and lawyers liability as distinct specialist lines.

Sources reviewed

01
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
02
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
03
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
04
Executive and Professional Liability | MMA
Marsh McLennan Agency · E&O, architects and engineers, and lawyers professional lines are named in the policy suite. · accessed 2026-09-30
05
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
06
Get business insurance
U.S. Small Business Administration · Six common types of business insurance table · accessed 2026-09-16