A Tale of M&A and Professional Liability: To Tail or Not to Tail

Acquisitions and major transactions raise many liability risk considerations for professional service firms. Should the acquired firm be added to the acquirer’s professional indemnity insurance policy? Is there sufficient coverage for claims arising from pre-merger work? Generally, how does professional liability coverage operate following an M&A transaction?

The answers to these questions, of course, depend upon the circumstances, including:

• The nature of the firms;
• The structure of the M&A deal;
• The costs of various ongoing coverage options; and
• The impact of existing policy language.

The policies of both the acquiring firm and the acquired firm may contain relevant restrictions requiring further review and response.

Structure of the Transaction

The best strategy for managing a Firm’s PI risk is guided by the structure of the M&A transaction.

• Asset only deal, including human capital
  
  

  Most professional service firm M&A transactions are structured as asset only deals. All or most of the partners and employees of the target are transitioned to the acquirer. The acquirer continues as the surviving legal entity, sometimes with a modified name to preserve and recognize the acquired firm’s brand and reputation. The acquired firm is generally dissolved, although in certain cases it is temporarily maintained as a run-off vehicle to facilitate the disposal of residual assets, leases, and other contractual obligations.

  Because liabilities are excluded from the asset deal and a run‑off vehicle may remain, choosing an extended reporting period under the acquired firm’s existing professional liability policy may be more attractive than adding full prior acts for the acquired firm.

• Full Merger
  
  

  Under a full merger, the legacy entities are terminated and consolidated into a new entity that assumes the combined operations, assets, liabilities, and governance framework of the merging firms.

• Full Acquisition
  
  

  The acquiring firm fully integrates the target, including its personnel, operating platforms, assets, and assumed liabilities in a full acquisition or stock deal.

Existing Policy Language

In considering an extended reporting period (ERP) for the acquired firm under their existing policy, it is important to review the limits available relative to expected future claims. Any exclusions or restrictions that could give an insurer grounds to deny potential claims should also be carefully reviewed.

The acquiring firm’s policy should be thoroughly evaluated to determine what coverage, if any, is automatically extended to the acquired firm and what steps must be taken to properly extend coverage to the acquired firm. These may include submitting detailed information about the acquired firm and paying an additional premium.

Tail Policies

When a firm ceases operation due to closure, retirement, or sale, it can purchase a tail policy or exercise an ERP on their existing policy. Both provide coverage for claims relating to services provided before a specific date, usually the day operations cease.

These policies have a set limit and retention with negotiated coverage periods. Coverage periods can vary across policy forms, but it makes sense to elect an ERP that aligns with the relevant jurisdiction’s statute of limitations, to avoid gaps in coverage for claims arising in the years following the transaction.

Requiring the acquired firm to purchase a tail policy helps isolate claims arising from the acquired firm’s prior acts, including claims that are not discovered until after the acquisition. Directing those claims to the tail policy shields the acquiring firm from successor liability claims and its insurance tower from matters predating the transaction.

However, tail coverage is costly to purchase and expires after the tail period. When tail coverage expires, or when coverage limits of tail policies are insufficient, plaintiffs may make a claim against the surviving firm.

Tail policy vs. Extended Reporting Period

While there are nuanced differences between an Extending Reporting Period and a Tail Policy, they functionally provide the same coverage.

The primary difference is that an ERP is exercised through the incumbent insurers of the acquired firm. while a tail policy is newly purchased.

Full Prior Acts

In some cases, it is more cost effective to have the acquiring firm assume all the acquired firm’s prior acts. Instead of having separate coverage for the acquired firm, all claims will be reported under the acquiring firm’s current insurance program, regardless of when the alleged error or omission was committed. This exposes the acquiring firm’s program limits to matters related to services provided by the acquired firm prior to the transaction date.

Accordingly, the acquiring firm should carefully assess the adequacy of its insurance program, along with the acquired firm’s claims history and reported circumstances, to determine whether its existing program can adequately cover the additional exposure.

This approach would likely result in an additional premium in the current policy and increased exposure and cost in future renewals. Electing an ERP could, in theory, provide some form of discount but this may not fully offset the increased exposure and thus result in a higher total cost of risk.

Other Considerations

Prior to the transaction close date, all reportable matters should be notified to both the acquiring firm and the target’s current insurers. This is crucial regardless of the post-close strategy being pursued. Under an ERP, many supplemental coverages such as subpoena assistance or forensic accounting sub-limits offered under the original policy language are no longer available. This may create coverage issues for firms that rely on these sub-limits.

Another consideration is the retention for claims arising from the acquired firm’s prior acts. It may be possible to negotiate a reduced retention for these matters. In the case of a tail policy, it is important to ensure the run-off vehicle is sufficiently funded to cover the retention of any claims that do arise.

If there are concerns about the total limits available under a tail policy, the acquiring firm can negotiate for its insurance program to sit excess of the tail. This would supplement the available limit while continuing to protect the surviving firm’s insurance tower from minor claims arising from prior acts discovered after the merger.

Conclusion

The optimal coverage choice depends upon the deal structure, each firm’s risk profile and the limits, language, and exclusions of all the relevant professional liability policies. Asset deals may favor a tail that isolates legacy risk, while full mergers or acquisitions may lean toward integrated full prior acts for consistency and administrative simplicity.

The key is balancing cost and the long‑term strength of the ongoing insurance program(s). This requires careful review of policy wording, exclusions, notice requirements, retentions and the limits needed for the combined firm.

Addressing these points as early as possible in the M&A process helps avoid coverage gaps and supports a smoother integration with robust protections against historical exposures.

Contact

The Professional Services Practice at Aon values your feedback. To discuss any of the topics raised in this insight, please contact Julia Kurolapnik or Huxley Anjilvel.


Julia Kurolapnik
Vice President and Director
Chicago





Huxley Anjilvel
Vice President and Director
Montreal

About Aon

Aon (NYSE: AON) exists to shape decisions for the better — to protect and enrich the lives of people around the world. Through actionable analytic insight, globally integrated Risk Capital and Human Capital expertise, and locally relevant solutions, our colleagues provide clients in over 120 countries with the clarity and confidence to make better risk and people decisions that help protect and grow their businesses.

Follow Aon on LinkedIn, X, Facebook and Instagram. Stay up-to-date by visiting Aon’s newsroom and sign up for news alerts here.

©2026 Aon plc. All rights reserved.

Aon is not a law firm or accounting firm and does not provide legal, financial or tax advice. Any commentary provided is based solely on Aon’s experience as insurance practitioners. We recommend that you consult with your own legal, financial and/or insurance advisors on any commentary provided herein. All descriptions, summaries or highlights of coverage described herein are for general informational purposes only and do not amend, alter or modify the actual terms and conditions of any relevant policy. Coverage is governed only by the terms and conditions of such policy. Insurance coverage in any particular case will depend upon the type of policy in effect, the terms, conditions and exclusions in any such policy, and the facts of each unique situation. No representation is made that any specific insurance coverage would apply in the circumstances outlined herein. Please refer to the individual policy forms for specific coverage details.

The information contained in this document and the statements expressed are of a general nature and are not intended to address the circumstances of any particular individual or entity.

This document is not intended to address any specific situation or to provide legal, regulatory, financial, or other advice. While care has been taken in the production of this document, Aon does not warrant, represent or guarantee the accuracy, adequacy, completeness or fitness for any purpose of the document or any part of it and can accept no liability for any loss incurred in any way by any person who may rely on it. Any recipient shall be responsible for the use to which it puts this document. This document has been compiled using information available to us up to its date of publication and is subject to any qualifications made in the document.

Insurance products and services offered by Aon Risk Insurance Services West, Inc., Aon Risk Services Central, Inc., Aon Risk Services Northeast, Inc., Aon Risk Services Southwest, Inc., and Aon Risk Services, Inc. of Florida and their licensed affiliates.