---
title: "At-Bay vs USI Insurance Services: Professional Liability (E&O) Insurance"
description: "At-Bay serves businesses of all revenue sizes with MPL limits up to $5 million; USI's AICPA program is limited to CPA firms and adds risk-management resources."
canonical: "https://spot.insure/compare/at-bay-vs-usi/professional-errors-omissions"
page-type: "line-comparison"
updated-at: "2026-09-25"
comparison-pair: "at-bay-vs-usi"
provider-a: "at-bay"
provider-b: "usi"
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, check_driving_insurance for source-backed rideshare and delivery requirements by state or province, compare_providers for sourced comparisons, get_provider_score for a published Reliability Score, get_rankings for current provider rankings, search_provider_reliability to filter Reliability 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/at-bay-vs-usi/professional-errors-omissions)

## Agent Guide

**What this page is:** Focused comparison of At-Bay and USI Insurance Services 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 At-Bay versus USI Insurance Services. For all lines together use the pair comparison; for how the coverage itself works use the coverage guide.

**Questions this page answers:**
- At-Bay vs USI Insurance Services for Professional Liability (E&O) Insurance: how do they differ?
- Which is better for Professional Liability (E&O) Insurance, At-Bay or USI Insurance Services?
- What does At-Bay or USI Insurance Services publish about Professional Liability (E&O) Insurance (limits, eligibility, claims, add-ons)?

**Key facts:**
- Line: Professional Liability (E&O) Insurance. Providers: At-Bay and USI Insurance Services.
- Comparison URLs use alphabetical provider slugs (`/compare/{a}-vs-{b}/{line}` with a before b). A reversed pair redirects permanently to the alphabetical one.

**Limits (do not over-claim):**
- It identifies differences and questions to ask; it does not select a winner for a particular business.
- 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; last updated 2026-09-25.

**Related pages:**
- [At-Bay vs USI Insurance Services](https://spot.insure/compare/at-bay-vs-usi) — all coverage lines for this pair
- [Professional Liability (E&O) Insurance guide](https://spot.insure/coverage/professional-errors-omissions) — how this coverage works
- [At-Bay profile](https://spot.insure/insurance-providers/at-bay) — provider profile
- [USI Insurance Services profile](https://spot.insure/insurance-providers/usi) — provider profile

# At-Bay vs USI Insurance Services: How Do They Compare for Professional Liability (E&O) Insurance?

CPA firms get a dedicated route with USI Insurance Services, the endorsed producer of the AICPA program underwritten by CNA. At-Bay provides primary miscellaneous professional liability for all revenue sizes up to $5 million, subject to state and eligibility rules.

At-Bay serves businesses of all revenue sizes with MPL limits up to $5 million; USI's AICPA program is limited to CPA firms.

## At-Bay vs USI Insurance Services Professional Liability (E&O) Insurance Summary

At-Bay serves businesses of all revenue sizes with MPL limits up to $5 million; USI's AICPA program is limited to CPA firms and adds risk-management resources. [1](https://www.at-bay.com/insurance/mpl/ "MPL Insurance: Coverage Highlights & Appetite") [5](https://www.usi.com/programs/affinity-programs/accountants-professional-liability/ "Accountants Professional Liability — USI Affinity")

## What Are the Key Differences Between At-Bay and USI Insurance Services Professional Liability (E&O) Insurance?

### Who Actually Carries the Risk

USI is specific about who's on the paper for its main CPA program:

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. [5](https://www.usi.com/programs/affinity-programs/accountants-professional-liability/ "Accountants Professional Liability — USI Affinity") (Evidence: Company-reported; scope: Direct quote from the AICPA program page; CNA underwrites only this named program, not USI's other professional-liability placements..)

At-Bay is not, at least not on its current MPL page. It does not name the insurer that would issue a new policy, and a 2023 press release referenced a different At-Bay entity for an unrelated coverage transition. [1](https://www.at-bay.com/insurance/mpl/ "MPL Insurance: Coverage Highlights & Appetite") [3](https://www.at-bay.com/press_releases/at-bay-doubles-mpl/ "At-Bay Doubles Miscellaneous Professional Liability Appetite")

For a buyer, that's the difference between knowing the carrier before you apply and having to ask. [1](https://www.at-bay.com/insurance/mpl/ "MPL Insurance: Coverage Highlights & Appetite") [5](https://www.usi.com/programs/affinity-programs/accountants-professional-liability/ "Accountants Professional Liability — USI Affinity")


### One Profession's Program Versus a Broad Appetite

USI built the AICPA program specifically for sole practitioners and regional CPA firms, distinct from its general Business Services practice that brokers E&O for other business types. [5](https://www.usi.com/programs/affinity-programs/accountants-professional-liability/ "Accountants Professional Liability — USI Affinity")

At-Bay describes its own audience more broadly: businesses of all revenue sizes, without naming CPA firms or any single profession as its focus. [1](https://www.at-bay.com/insurance/mpl/ "MPL Insurance: Coverage Highlights & Appetite")

If you're not a CPA firm, USI's named program simply doesn't apply to you the way it would to an accounting practice. [5](https://www.usi.com/programs/affinity-programs/accountants-professional-liability/ "Accountants Professional Liability — USI Affinity")


### What You Get Beyond the Policy Itself

USI says AICPA program members also get supportive claims handling and risk-management resources, including engagement-letter templates. [5](https://www.usi.com/programs/affinity-programs/accountants-professional-liability/ "Accountants Professional Liability — USI Affinity")

At-Bay's page instead names mechanics built into the policy itself, like an 80/20 hammer clause and disciplinary-proceedings defense, without describing comparable risk-management extras. [1](https://www.at-bay.com/insurance/mpl/ "MPL Insurance: Coverage Highlights & Appetite")

## What Should You Confirm in At-Bay and USI Insurance Services Professional Liability (E&O) Insurance Quotes?

- If you're a CPA firm, confirm CNA is still the underwriter on the AICPA program's current declarations. [5](https://www.usi.com/programs/affinity-programs/accountants-professional-liability/ "Accountants Professional Liability — USI Affinity")
- Ask At-Bay directly which insurer would issue your MPL policy. [1](https://www.at-bay.com/insurance/mpl/ "MPL Insurance: Coverage Highlights & Appetite")
- Ask USI whether your business qualifies for the AICPA program or falls under its general Business Services E&O practice instead. [5](https://www.usi.com/programs/affinity-programs/accountants-professional-liability/ "Accountants Professional Liability — USI Affinity")
- Ask At-Bay for its published $5 million limit ceiling and any state restrictions that apply to your business. [1](https://www.at-bay.com/insurance/mpl/ "MPL Insurance: Coverage Highlights & Appetite")
- Ask USI for specific limit, retention, or premium figures, since the AICPA program page does not publish them. [5](https://www.usi.com/programs/affinity-programs/accountants-professional-liability/ "Accountants Professional Liability — USI Affinity")

## At-Bay vs USI Insurance Services Professional Liability (E&O) Compared

| Criteria | At-Bay Miscellaneous Professional Liability (MPL) Insurance | AICPA Professional Liability Program (USI Affinity) |
| --- | --- | --- |
| Who It’s For | At-Bay says it provides primary MPL for businesses of all revenue sizes with limits up to $5 million, subject to state restrictions and eligibility requirements detailed in a separate MPL appetite guide. [1](https://www.at-bay.com/insurance/mpl/ "MPL Insurance: Coverage Highlights & Appetite") (Evidence: Company-reported; scope: Current MPL appetite paragraph; the linked appetite guide's specific eligibility requirements were not independently opened for this record..) | 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. [5](https://www.usi.com/programs/affinity-programs/accountants-professional-liability/ "Accountants Professional Liability — USI Affinity") (Evidence: Company-reported; scope: Program page description..) |
| How to Apply | At-Bay directs MPL submissions to underwriting by email or through automatic quotes on its Broker Platform, which At-Bay describes as a workflow of creating a quote, customizing limits and retentions, and binding the policy. [1](https://www.at-bay.com/insurance/mpl/ "MPL Insurance: Coverage Highlights & Appetite") [4](https://www.at-bay.com/brokers/platform/ "Broker Platform") (Evidence: Company-reported; scope: Current submission instructions and the general broker-platform workflow description; MPL-specific automation details were not separately confirmed..) | 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. [5](https://www.usi.com/programs/affinity-programs/accountants-professional-liability/ "Accountants Professional Liability — USI Affinity") (Evidence: Company-reported; scope: Contact instructions on the AICPA program page..) |
| Coverage Features | At-Bay lists MPL coverage highlights including automatic coverage for acquired subsidiaries, claims-made-and-reported coverage, coverage for independent contractors, disciplinary-proceedings defense, a duty-to-defend contract, personal-injury coverage (including emotional distress), punitive damages where insurable, a professional-services definition written for each insured, and an 80/20 hammer clause. [1](https://www.at-bay.com/insurance/mpl/ "MPL Insurance: Coverage Highlights & Appetite") (Evidence: Company-reported; scope: Product-page coverage-highlights list; an 80/20 hammer clause is a settlement provision where the insurer pays 80% and the insured pays 20% of costs after the insured declines a recommended settlement. The issued policy and declarations control actual wording, limits and exclusions..) | 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. [5](https://www.usi.com/programs/affinity-programs/accountants-professional-liability/ "Accountants Professional Liability — USI Affinity") (Evidence: Company-reported; scope: Program page description; actual insuring agreements, exclusions and conditions are set by the issued CNA policy form..) |
| Role in This Line | At-Bay markets MPL as one of its own named insurance products, sold through its disclosed producer, At-Bay Insurance Services LLC, with the product page directed at "properly licensed insurance professionals" submitting business rather than at direct retail buyers. [1](https://www.at-bay.com/insurance/mpl/ "MPL Insurance: Coverage Highlights & Appetite") [2](https://www.at-bay.com/licenses/ "Licenses") (Evidence: Company-reported; scope: Current MPL product page and license disclosures; this describes the distribution channel, not who bears the underwriting risk..) | 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. [5](https://www.usi.com/programs/affinity-programs/accountants-professional-liability/ "Accountants Professional Liability — USI Affinity") [7](https://www.usi.com/property-casualty/business-services/ "Business Services") (Evidence: Company-reported; scope: AICPA program page and Business Services practice page..) |

## About At-Bay and USI Insurance Services

- [At-Bay company profile](https://spot.insure/insurance-providers/at-bay) · [At-Bay customer reviews](https://spot.insure/insurance-providers/at-bay/reviews)
- [USI Insurance Services company profile](https://spot.insure/insurance-providers/usi) · [USI Insurance Services customer reviews](https://spot.insure/insurance-providers/usi/reviews)
- [What Is Professional Errors and Omissions (E&O) Insurance?](https://spot.insure/coverage/professional-errors-omissions)

## Related Pages for At-Bay vs USI Insurance Services

- [At-Bay vs USI Insurance Services](https://spot.insure/compare/at-bay-vs-usi): 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.
- [At-Bay Professional Liability (E&O) Insurance](https://spot.insure/insurance-providers/at-bay/professional-errors-omissions)
- [USI Insurance Services Professional Liability (E&O) Insurance](https://spot.insure/insurance-providers/usi/professional-errors-omissions)

## Sources for At-Bay vs USI Insurance Services

### Sources About At-Bay

1. [MPL Insurance: Coverage Highlights & Appetite](https://www.at-bay.com/insurance/mpl/). At-Bay; MPL Coverage Highlights list; MPL Appetite paragraph; Send us your submissions; "material on this page is intended for use solely by properly licensed insurance professionals". Accessed 2026-09-23.
2. [Licenses](https://www.at-bay.com/licenses/). At-Bay; Producer introduction; agency and surplus-lines footer naming At-Bay Insurance Services LLC. Accessed 2026-09-16.
3. [At-Bay Doubles Miscellaneous Professional Liability Appetite](https://www.at-bay.com/press_releases/at-bay-doubles-mpl/). At-Bay; September 28, 2023 release: final paragraph before Media Contacts. Accessed 2026-09-16.
4. [Broker Platform](https://www.at-bay.com/brokers/platform/). At-Bay; How it works: Create a quote, Customize your quote, Bind your policy, Manage renewals; FAQs. Accessed 2026-09-16.

### Sources About USI Insurance Services

5. [Accountants Professional Liability — USI Affinity](https://www.usi.com/programs/affinity-programs/accountants-professional-liability/). 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.
6. [USI Specialty Program Solutions](https://www.usi.com/programs/). 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.
7. [Business Services](https://www.usi.com/property-casualty/business-services/). USI Insurance Services; USI advises clients...and provides solutions for...Errors & Omissions/Professional Liability.... Accessed 2026-09-23.

Updated 2026-09-25. 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.

## Agent and Developer Resources

- [Markdown page](https://spot.insure/compare/at-bay-vs-usi/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)