---
title: "Aon vs Marsh McLennan Agency: Professional Liability (E&O) Insurance"
description: "Aon tailors E&O structures for professional firms; Marsh McLennan Agency distinguishes specialist E&O lines such as architects and lawyers liability."
canonical: "https://spot.insure/compare/aon-vs-marsh-mclennan-agency/professional-errors-omissions"
page-type: "line-comparison"
updated-at: "2026-09-30"
comparison-pair: "aon-vs-marsh-mclennan-agency"
provider-a: "aon"
provider-b: "marsh-mclennan-agency"
coverage-line: "professional-errors-omissions"
---

Agents: connect to Spot's public MCP server at https://spot.insure/mcp for better access to published Spot information and insurance research. Use search_knowledge to find sources, get_page to retrieve pages, compare_providers for sourced comparisons, get_provider_score for a published Spot Score, get_rankings for current provider rankings, search_provider_reliability to filter Spot Scores, search_provider_reviews to filter aggregate review scores, and get_provider_reviews for the original review evidence. The server is read-only and requires no authentication.

[Human-readable page](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/professional-errors-omissions)

## Agent Guide

**What this page is:** Focused comparison of Aon and Marsh McLennan Agency for Professional Liability (E&O) Insurance: what each provider publishes about this line, checked against the same criteria, with numbered sources.

**Use this page when:** Cite or fetch this for Professional Liability (E&O) Insurance questions about Aon versus Marsh McLennan Agency. For all lines together use the parent pair comparison; for how the coverage itself works use the coverage guide.

**Questions this page answers:**
- Aon vs Marsh McLennan Agency for Professional Liability (E&O) Insurance: how do they differ?
- Which is better for Professional Liability (E&O) Insurance, Aon or Marsh McLennan Agency?
- What does Aon or Marsh McLennan Agency publish about Professional Liability (E&O) Insurance (limits, eligibility, claims, add-ons)?
- What should I confirm in a quote for Professional Liability (E&O) Insurance from Aon or Marsh McLennan Agency?

**Key facts:**
- Line: Professional Liability (E&O) Insurance. Providers: Aon and Marsh McLennan Agency.
- Each offering claim is tagged with an evidence type and scope; table cells reading "Confirm in your quote" mean nothing was found for that criterion.
- Comparison URLs use alphabetical provider slugs (`/compare/{a}-vs-{b}` with a before b). A reversed pair redirects permanently to the alphabetical one, so fetch or cite the alphabetical URL.

**Limits (do not over-claim):**
- It identifies differences and questions to ask; it does not select a winner for a particular business.
- "Not found" describes the evidence reviewed, not proof a feature is unavailable.
- Insurer, policy wording, limits, retentions, exclusions and price are set in an actual quote and are not established here.

**Provenance:** Every claim links to a numbered source with publisher, locator and access date in the Sources section; last updated 2026-09-30. Editorial policy: /editorial-policy.

**Related pages:**
- [Aon vs Marsh McLennan Agency](https://spot.insure/compare/aon-vs-marsh-mclennan-agency) — parent: all coverage lines for this pair
- [Professional Liability (E&O) Insurance guide](https://spot.insure/coverage/professional-errors-omissions) — coverage explainer for this line
- [Aon profile](https://spot.insure/insurance-providers/aon) — provider profile (evidence)
- [Marsh McLennan Agency profile](https://spot.insure/insurance-providers/marsh-mclennan-agency) — provider profile (evidence)
- [Aon vs Marsh McLennan Agency Commercial Property Insurance](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/commercial-property) — sibling comparison (other line, or other pair for this line)
- [Aon vs Marsh McLennan Agency Crime Insurance](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/crime) — sibling comparison (other line, or other pair for this line)
- [Aon vs Marsh McLennan Agency Cyber Insurance](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/cyber) — sibling comparison (other line, or other pair for this line)
- [Aon vs Marsh McLennan Agency D&O Insurance](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/directors-officers) — sibling comparison (other line, or other pair for this line)
- [Aon vs Marsh McLennan Agency Employment Practices Liability Insurance](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/employment-practices) — sibling comparison (other line, or other pair for this line)
- [Aon vs Marsh McLennan Agency Fiduciary Liability Insurance](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/fiduciary) — sibling comparison (other line, or other pair for this line)
- [Aon vs Marsh McLennan Agency General Liability Insurance](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/general-liability) — sibling comparison (other line, or other pair for this line)
- [Aon vs Marsh McLennan Agency Kidnap and Ransom Insurance](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/kidnap-ransom) — sibling comparison (other line, or other pair for this line)
- [Aon vs Marsh McLennan Agency Workers’ Compensation Insurance](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/workers-compensation) — sibling comparison (other line, or other pair for this line)
- [AIG vs Aon Professional Liability (E&O) Insurance](https://spot.insure/compare/aig-vs-aon/professional-errors-omissions) — sibling comparison (other line, or other pair for this line)
- [AIG vs Marsh McLennan Agency Professional Liability (E&O) Insurance](https://spot.insure/compare/aig-vs-marsh-mclennan-agency/professional-errors-omissions) — sibling comparison (other line, or other pair for this line)
- [Alliance Risk vs Aon Professional Liability (E&O) Insurance](https://spot.insure/compare/alliance-risk-vs-aon/professional-errors-omissions) — sibling comparison (other line, or other pair for this line)
- [Aon vs At-Bay Professional Liability (E&O) Insurance](https://spot.insure/compare/aon-vs-at-bay/professional-errors-omissions) — sibling comparison (other line, or other pair for this line)
- [Aon vs The Baldwin Group Professional Liability (E&O) Insurance](https://spot.insure/compare/aon-vs-baldwin/professional-errors-omissions) — sibling comparison (other line, or other pair for this line)
- [Aon vs Beazley Professional Liability (E&O) Insurance](https://spot.insure/compare/aon-vs-beazley/professional-errors-omissions) — sibling comparison (other line, or other pair for this line)

# Aon vs Marsh McLennan Agency: How Do They Compare for Professional Liability (E&O) Insurance?

Aon tailors E&O structures for professional firms; Marsh McLennan Agency distinguishes specialist E&O lines such as architects and lawyers liability.

## Research Scope and Use

Use this comparison to evaluate Aon and Marsh McLennan Agency for Professional Liability (E&O) Insurance against the same documented criteria. It identifies differences and questions to confirm; it does not select a winner for a particular business. Offering claims are what each provider publishes about this line unless marked otherwise. “Not found” describes the evidence reviewed, not proof that a feature is unavailable. Confirm the insurer, policy wording, limits, retentions, exclusions and cost in an actual quote.

## Summary

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. [3](https://www.aon.com/en/capabilities/risk-transfer/professional-services-practice "Professional Services Practice") [6](https://www.marshmma.com/us/solutions/executive-and-professional-liability.html "Executive and Professional Liability | MMA")

## 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](https://www.aon.com/en/about/leadership-and-governance/brokerage-terms-of-service-for-commercial-risk-solutions-us "Commercial Risk Solutions U.S. Brokerage Terms of Service") [2](https://www.aon.com/en/capabilities/middle-market-clients "Middle Market Clients")

[Aon profile](https://spot.insure/insurance-providers/aon)

## What Is Marsh McLennan Agency?

Marsh McLennan Agency provides business insurance and employee health and benefits, alongside retirement, wealth, and private-client services across the United States and Canada. Its US small-business page lists six common coverage types and directs buyers to request a personalized quote by phone; the insurer and terms for a specific placement must be confirmed in the proposal. [4](https://www.marshmma.com/us/mma/about-us.html "Who We Are") [5](https://www.marshmma.com/us/solutions/small-business.html "Small Business Insurance Solutions")

[Marsh McLennan Agency profile](https://spot.insure/insurance-providers/marsh-mclennan-agency)

## 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. [7](https://www.tdi.texas.gov/commercial/pl-faq.html "FAQ: Professional liability insurance") [8](https://www.iii.org/article/professional-liability-insurance "Professional liability insurance") [9](https://www.sba.gov/counseling/launch-your-business/#business-insurance "Get business insurance") [10](https://www.hiscox.com/documents/pl-sample-policy-wording.pdf "Professional Liability – US Direct Errors and Omissions Insurance")

## Key Differences in 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. [3](https://www.aon.com/en/capabilities/risk-transfer/professional-services-practice "Professional Services Practice") [6](https://www.marshmma.com/us/solutions/executive-and-professional-liability.html "Executive and Professional Liability | MMA")

### 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. [3](https://www.aon.com/en/capabilities/risk-transfer/professional-services-practice "Professional Services Practice") [6](https://www.marshmma.com/us/solutions/executive-and-professional-liability.html "Executive and Professional Liability | MMA")

## What to Confirm in Professional Liability (E&O) Insurance Quotes

- Ask Marsh McLennan Agency whether your profession needs its named specialist form and request its terms and limits. [3](https://www.aon.com/en/capabilities/risk-transfer/professional-services-practice "Professional Services Practice") [6](https://www.marshmma.com/us/solutions/executive-and-professional-liability.html "Executive and Professional Liability | MMA")
- Ask Aon which carrier and professional-services definition it proposes for your work. [3](https://www.aon.com/en/capabilities/risk-transfer/professional-services-practice "Professional Services Practice") [6](https://www.marshmma.com/us/solutions/executive-and-professional-liability.html "Executive and Professional Liability | MMA")

## Offering Details

| Criteria | Aon Professional Liability / E&O brokerage and risk-advisory offering | Marsh McLennan Agency professional errors omissions (official overview) |
| --- | --- | --- |
| 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. [3](https://www.aon.com/en/capabilities/risk-transfer/professional-services-practice "Professional Services Practice") (Evidence: Company-reported; scope: Aon’s global professional-services practice page. This establishes a marketed brokerage/advisory offering, not policy issuance or account-specific placement..) | Marsh McLennan Agency describes arranging professional errors omissions for the audience stated on the cited product page. [6](https://www.marshmma.com/us/solutions/executive-and-professional-liability.html "Executive and Professional Liability | MMA") (Evidence: Company-reported; scope: 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..) |
| 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. [3](https://www.aon.com/en/capabilities/risk-transfer/professional-services-practice "Professional Services Practice") (Evidence: Not found in reviewed sources; scope: 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..) | Confirm in your quote. |
| 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. [3](https://www.aon.com/en/capabilities/risk-transfer/professional-services-practice "Professional Services Practice") (Evidence: Company-reported; scope: Audience described for Aon’s global professional-services practice. It does not establish U.S. state availability or underwriting eligibility for a placement..) | Organizations seeking professional liability placement; source does not imply all professions share one policy. [6](https://www.marshmma.com/us/solutions/executive-and-professional-liability.html "Executive and Professional Liability | MMA") (Evidence: Company-reported; scope: 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..) |
| 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. [3](https://www.aon.com/en/capabilities/risk-transfer/professional-services-practice "Professional Services Practice") (Evidence: Company-reported; scope: 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..) | 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. [6](https://www.marshmma.com/us/solutions/executive-and-professional-liability.html "Executive and Professional Liability | MMA") (Evidence: Company-reported; scope: 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..) |
| 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. [3](https://www.aon.com/en/capabilities/risk-transfer/professional-services-practice "Professional Services Practice") (Evidence: Not publicly disclosed; scope: Aon’s global practice page as reviewed 2026-09-30; no quote, bond form or issued policy was reviewed..) | 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. [6](https://www.marshmma.com/us/solutions/executive-and-professional-liability.html "Executive and Professional Liability | MMA") (Evidence: Not publicly disclosed; scope: Only the cited marketing page was reviewed for published limit and retention information; no policy-form entitlement is inferred..) |
| 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. [3](https://www.aon.com/en/capabilities/risk-transfer/professional-services-practice "Professional Services Practice") (Evidence: Company-reported; scope: Company-reported advisory services on Aon’s global practice page; account-specific service scope is not stated..) | Confirm in your quote. |
| How to Apply | Confirm in your quote. | 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. [6](https://www.marshmma.com/us/solutions/executive-and-professional-liability.html "Executive and Professional Liability | MMA") (Evidence: Company-reported; scope: 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..) |

## Full Comparison

- [Aon vs Marsh McLennan Agency](https://spot.insure/compare/aon-vs-marsh-mclennan-agency): all coverage lines, business roles, service and claims.
- [What Is Professional Errors and Omissions (E&O) Insurance?](https://spot.insure/coverage/professional-errors-omissions): Professional liability can help pay covered defense costs and losses when a client says your advice or service caused financial harm; check services and reporting terms.
- [Aon vs Marsh McLennan Agency Commercial Property Insurance](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/commercial-property)
- [Aon vs Marsh McLennan Agency Crime Insurance](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/crime)
- [Aon vs Marsh McLennan Agency Cyber Insurance](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/cyber)
- [Aon vs Marsh McLennan Agency D&O Insurance](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/directors-officers)
- [Aon vs Marsh McLennan Agency Employment Practices Liability Insurance](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/employment-practices)
- [Aon vs Marsh McLennan Agency Fiduciary Liability Insurance](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/fiduciary)
- [Aon vs Marsh McLennan Agency General Liability Insurance](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/general-liability)
- [Aon vs Marsh McLennan Agency Kidnap and Ransom Insurance](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/kidnap-ransom)
- [Aon vs Marsh McLennan Agency Workers’ Compensation Insurance](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/workers-compensation)
- [AIG vs Aon Professional Liability (E&O) Insurance](https://spot.insure/compare/aig-vs-aon/professional-errors-omissions)
- [AIG vs Marsh McLennan Agency Professional Liability (E&O) Insurance](https://spot.insure/compare/aig-vs-marsh-mclennan-agency/professional-errors-omissions)
- [Alliance Risk vs Aon Professional Liability (E&O) Insurance](https://spot.insure/compare/alliance-risk-vs-aon/professional-errors-omissions)
- [Aon vs At-Bay Professional Liability (E&O) Insurance](https://spot.insure/compare/aon-vs-at-bay/professional-errors-omissions)
- [Aon vs The Baldwin Group Professional Liability (E&O) Insurance](https://spot.insure/compare/aon-vs-baldwin/professional-errors-omissions)
- [Aon vs Beazley Professional Liability (E&O) Insurance](https://spot.insure/compare/aon-vs-beazley/professional-errors-omissions)

## Sources

### Aon

1. [Commercial Risk Solutions U.S. Brokerage Terms of Service](https://www.aon.com/en/about/leadership-and-governance/brokerage-terms-of-service-for-commercial-risk-solutions-us). 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.
2. [Middle Market Clients](https://www.aon.com/en/capabilities/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.
3. [Professional Services Practice](https://www.aon.com/en/capabilities/risk-transfer/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.

### Marsh McLennan Agency

4. [Who We Are](https://www.marshmma.com/us/mma/about-us.html). Marsh McLennan Agency; Lines 193-195: ‘a business of Marsh’ and company-listed service lines across US and Canada. This does not establish the legal entity for an account, corporate ownership chart, or insurer role.. Accessed 2026-09-29.
5. [Small Business Insurance Solutions](https://www.marshmma.com/us/solutions/small-business.html). Marsh McLennan Agency; Lines 205-207: small-business audience and call invitation; lines 224-249 list six coverage categories and short descriptions; line 264 is an embedded form whose function is not stated. No form submitted.. Accessed 2026-09-29.
6. [Executive and Professional Liability | MMA](https://www.marshmma.com/us/solutions/executive-and-professional-liability.html). Marsh McLennan Agency; E&O, architects and engineers, and lawyers professional lines are named in the policy suite.. Accessed 2026-09-30.

### Professional Liability (E&O) Insurance Guide

7. [FAQ: Professional liability insurance](https://www.tdi.texas.gov/commercial/pl-faq.html). 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.
8. [Professional liability insurance](https://www.iii.org/article/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.
9. [Get business insurance](https://www.sba.gov/counseling/launch-your-business/#business-insurance). U.S. Small Business Administration; Six common types of business insurance table. Accessed 2026-09-16.
10. [Professional Liability – US Direct Errors and Omissions Insurance](https://www.hiscox.com/documents/pl-sample-policy-wording.pdf). 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.

Updated 2026-09-30. Spot, a product of Tools for Enlightenment, publishes this research and works in the commercial insurance market. The comparison applies the same criteria to both providers. [Editorial policy](https://spot.insure/editorial-policy). To suggest a correction, [contact Spot](https://spot.insure/contact) with the page URL and supporting source.

## Aon Reviews

Review Score: 6.1 / 10 from 3 rated sources, equally weighted.

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.

- J.D. Power: Aon study score 822 (out of 1000). Historical 2017 large-commercial-broker study; U.S. and Canada commercial insurance decision-makers at large organizations. J.D. Power reports 2,506 evaluations across the study, not Aon-specific responses; the Aon respondent count is not stated. Period: 2017 study; ranked 3rd among large commercial brokers; study-wide population 2,506, not Aon review count. Checked 2026-09-29. [Diversity of Offerings Becomes Key Differentiator for Large Commercial Insurers, JD Power Finds](https://www.jdpower.com/business/press-releases/jd-power-2017-large-commercial-insurance-study)
- Trustpilot: TrustScore 1.2 (out of 5); 782 reviews. Global www.aon.com profile merged with other Aon profiles; mixed experiences include pensions, travel, professional indemnity and Australian business quotation service. The two latter complaints are individual unverified allegations, not evidence of U.S. commercial-placement outcomes or insurer fault. Trustpilot says reviews may not be representative because the company has not recently invited reviews. Period: Displayed 2026-09-29; page separately showed 198 reviews in the last 12 months. Checked 2026-09-29. [Aon Reviews](https://www.trustpilot.com/review/www.aon.com)
- BBB: BBB business grade B− (BBB letter grade; stated reason: failure to respond to two filed complaints). BBB of Chicago & Northern Illinois profile for Aon plc; the business grade is BBB’s own measure, not customer stars. Checked 2026-09-29. [Aon plc | BBB Business Profile](https://www.bbb.org/us/il/chicago/profile/insurance-companies/aon-plc-0654-5291)
- BBB: BBB customer review average 1.6 (out of 5); 5 reviews. BBB of Chicago & Northern Illinois customer reviews for Aon plc; some reviews are about employee-benefit and medical-expense issues. Period: checked 2026-09-29. Checked 2026-09-29. [Aon plc | BBB Reviews](https://www.bbb.org/us/il/chicago/profile/insurance-companies/aon-plc-0654-5291/customer-reviews)

Reviewed 2026-09-29. [Read the sourced review](https://spot.insure/insurance-providers/aon/reviews).

## Marsh McLennan Agency Reviews

Review Score: 8.2 / 10 from 2 rated sources, equally weighted.

There are almost no public customer reviews of Marsh McLennan Agency (MMA). Trustpilot shows 3.2 out of 5, but from a single review, and BBB shows an A grade with four complaints closed in three years.

- Trustpilot: TrustScore 3.2 (out of 5); 1 reviews. Trustpilot profile for marshmma.com, MMA's own domain. Unclaimed; MMA has not invited reviews. Period: checked 2026-09-29. Checked 2026-09-29. [marshmma.com Trustpilot profile](https://www.trustpilot.com/review/marshmma.com)
- Trustpilot: TrustScore (Marsh brand) 1.3 (out of 5); 115 reviews. Trustpilot page for marsh.com, the global Marsh brand (mostly individual and non-US customers). This is a different entity from MMA. Period: checked 2026-09-29. Checked 2026-09-29. [Marsh Reviews](https://www.trustpilot.com/review/www.marsh.com)
- BBB: BBB business grade A. BBB San Diego-area profile for Marsh & McLennan Agency LLC (accredited). MMA has separate BBB profiles per office; Dayton and Schaumburg both show A+. Checked 2026-09-29. [Marsh & McLennan Agency LLC (San Diego) BBB](https://www.bbb.org/us/ca/san-diego/profile/insurance-services-office/marsh-mclennan-agency-llc-1126-3000103)
- BBB: Complaints 4. Same San Diego-area profile; zero customer reviews. No client-count denominator. Period: closed in the last three years (checked 2026-09-29). Checked 2026-09-29. [Marsh & McLennan Agency LLC — BBB Complaints](https://www.bbb.org/us/ca/san-diego/profile/insurance-services-office/marsh-mclennan-agency-llc-1126-3000103/complaints); [Marsh & McLennan Agency LLC — BBB Reviews](https://www.bbb.org/us/ca/san-diego/profile/insurance-services-office/marsh-mclennan-agency-llc-1126-3000103/customer-reviews)

Reviewed 2026-09-29. [Read the sourced review](https://spot.insure/insurance-providers/marsh-mclennan-agency/reviews).

## Agent and Developer Resources

- [Markdown page](https://spot.insure/compare/aon-vs-marsh-mclennan-agency/professional-errors-omissions.md)
- [Developer resources](https://spot.insure/developers)
- [Public MCP server](https://spot.insure/mcp)
- [MCP server manifest](https://spot.insure/server.json)
- [OpenAPI description](https://spot.insure/openapi.json)
- [Public page index](https://spot.insure/llms.txt)