Mergers and acquisitions between law firms have PI implications that are commonly underestimated during the deal. The MTC's successor practice rules can shift liability for an acquired firm's historical work onto the surviving entity, and the resulting premium impact can be material. This article walks through what the rules actually say, what they mean in practice, and the questions to put on the deal checklist.
It complements the full Solicitors PI Guide and the Solicitors sector page.
The default rule: the surviving practice inherits the predecessor's tail
Under the SRA Minimum Terms, when one practice succeeds another (whether through merger, acquisition, demerger, or change of legal entity), the surviving practice is generally treated as the successor for PI purposes. Practically, that means:
- Claims arising from work the predecessor did, but not notified before the deal, attach to the surviving practice's PI cover going forward.
- The run-off obligation of the predecessor passes to the surviving practice. The predecessor does not separately have to maintain run-off cover; the successor absorbs the exposure (unless the predecessor elects otherwise; see below).
- The successor's PI insurer at the next renewal will rate the combined firm's claims history, including any claims and circumstances inherited from the predecessor.
The mechanics are set out across several MTC provisions:
- Clause 1.1 requires the policy to cover the prior practice and any successor practice as part of standard civil liability cover.
- Clause 4.7 prohibits retroactive date exclusions.
- Clause 4.8 addresses double insurance situations between two or more insurers of the successor practice.
- Clause 4.8A allows the SRA to direct an insurer to conduct a claim and advance defence costs pending resolution of any coverage dispute.
- Clause 5.5 gives the ceasing firm an election: it can opt to be insured under its own six-year run-off, or (if there is MTC-compliant insurance for the successor) to be insured as a prior practice under the successor's policy.
The detailed definition of "successor practice" sits in the MTC Glossary, and it is substantive rather than purely formal: it looks at holding out, principals moving across, name continuity, premises continuity, transfer of goodwill, assumption of liabilities, and majority transfer of staff.
Why this matters more than buyers usually realise
The temptation in any law firm merger is to focus on the headline value drivers: fee income synergies, partner economics, real estate, IT integration. PI typically sits with the COFA or COLP and gets less attention than it deserves. Three specific risks:
Hidden claims tail. The acquired firm's claims-made PI policy responds only to claims notified during the policy period. Claims from work the acquired firm did, but which haven't yet emerged, will surface against the successor's PI cover. If the acquired firm had a historic pattern of conveyancing claims, residential-build defects, or trust drafting errors, that exposure is now the successor's problem.
Combined-firm rating shock. The successor's PI insurer at next renewal does not look at the two firms' claims histories separately. It rates the combined entity. A clean-record buyer acquiring a firm with a difficult claims history can see a step-change in their next premium that swamps the deal's projected economics.
The election under clause 5.5. The ceasing firm can elect, before cessation, whether to be insured under its own six-year run-off cover or as a prior practice under the successor's ongoing policy. The economics of these two routes differ materially. The election should be a structured decision taken in conjunction with both the buyer's and seller's brokers, not an afterthought after the deal closes. If no election is made before cessation, clause 5.5(b) applies by default: the ceased practice is treated as a prior practice under the successor's policy.
The pre-deal questions buyers should ask
If you're acquiring or merging with another firm, the PI due diligence should answer:
About the target's PI history:
- What is the target's complete claims history for the last six years? (Past the typical insurer look-back window. Buyers should see further.)
- Are there any circumstances currently notified but not yet crystallised into claims?
- Has the target ever been refused PI cover or seen an insurer withdraw?
- Are there specific work types or office locations associated with elevated claims experience?
- What was the target's most recent renewal premium and what was the renewal outcome?
About the target's current PI cover:
- Who is the current insurer and what is the policy expiry?
- What is the current limit and excess structure?
- Are there any exclusions or specific carve-outs on the current cover?
- What is the current premium and how does it compare to peer firms of similar size?
About the deal structure:
- Is the transaction structured as an asset purchase, share purchase, or merger?
- Does the predecessor entity continue to exist post-completion or cease?
- Are there any retained liabilities held back from the successor?
- Has the buyer's PI insurer been notified of the proposed transaction?
The structure question affects whether the successor practice rules are likely to apply, but the test is substantive. The MTC Glossary definition looks at multiple fact-patterns (holding out as successor, sole practitioner becoming principal/employee of the buyer, majority of partners moving across, name continuity, premises continuity, goodwill/asset transfer, assumption of liabilities, majority staff transfer). An asset purchase can establish a successor practice if the substantive criteria are met. The SRA looks at substance, not just legal form.
Practical workflow for a clean PI handover
The cleanest way to handle PI in a merger is to engage both the buyer's and seller's brokers early and run a parallel workstream alongside the legal deal. The typical sequence:
Pre-signing.
- Buyer's broker receives full disclosure of target's PI history (six years of claims, current policy, any notified circumstances).
- Buyer's insurer is notified of the proposed transaction and asked to indicate the likely renewal position of the combined entity.
- If the indicative response is materially negative, the deal economics are revisited or the buyer negotiates retention provisions.
Signing to completion.
- The current PI policy of the target firm runs to its expiry. Material changes (the merger itself) are disclosed to the insurer.
- The successor practice arrangements are documented (typically a deed or formal letter establishing which entity is the successor for PI purposes).
- The clause 5.5 election is made: run-off for the ceased practice, or treatment as a prior practice under the successor's cover.
Post-completion.
- At the combined entity's next renewal, the buyer's broker submits the combined firm to market.
- Premium and limit reset based on the combined claims history, work mix, and fee income.
- If the predecessor entity has formally ceased and run-off was elected, this is reflected in arrangements with the predecessor's insurer.
Common mistakes
Mistake 1: PI handled by the COFA only, not surfaced to the deal team.
The acquired firm's COFA is the right person to assemble the PI disclosure pack, but the deal team needs to see the headline implications. Premium step-change risk should be modelled into the deal P&L, not discovered at the first renewal.
Mistake 2: Asset purchase treated as PI-free.
Acquiring the book of clients in an asset purchase, while leaving the seller's old entity in place, does not automatically insulate the buyer from successor practice rules. The substance of the transaction (continuity of clients, partners, work, name, premises) can establish a successor relationship even where the legal form is an asset purchase.
Mistake 3: Clause 5.5 election forgotten.
If no election is made before cessation, clause 5.5(b) applies by default and the ceased practice is treated as a prior practice under the successor's policy. That may or may not be the better economic outcome; it should be a chosen result, not a defaulted one.
Mistake 4: No insurer notification.
Both the buyer's and seller's insurers should be notified of a proposed merger before completion. Late notification can compromise cover for any claims arising from the deal period.
Mistake 5: Pending coverage disputes.
If there is an unresolved coverage dispute on a notified claim, MTC clause 4.8A allows the SRA to direct the relevant insurer to conduct the claim and advance defence costs while the dispute is resolved. Useful protection if a claim is mid-flight when a merger is being structured.
What the SRA expects
The SRA Authorisation of Firms Rules require firms to notify changes in ownership, control, and material changes in the firm's authorised activities. The relevant submissions are made through the firm's mySRA account.
Substantively, the SRA expects:
- Notification of the proposed structural change through the appropriate mySRA forms.
- Continuity of cover such that no gap exists between predecessor and successor.
- Clear documentation of which entity is the regulated practice going forward.
A merger that creates a brief gap in cover, even unintentionally, is a regulatory issue and exposes the firm to claims that would otherwise have been covered.
Special case: partner-only acquisition
When a partner leaves one firm and joins another, taking some clients with them, that is typically not a "merger" or "successor practice" event for PI purposes. The departing partner's prior firm continues to be the relevant entity for PI on work done at the prior firm; the new firm picks up cover for work done from the date of joining.
The exception: if the partner brings substantially all of a former firm's work over (effectively a de facto merger), the successor analysis can apply even where the legal form is just a partner move. The MTC Glossary test is substantive: it looks at majority transfer of principals, holding out, premises and name continuity, transfer of goodwill, and assumption of liabilities. There is no specific percentage threshold; the test is whether the substantive fact-patterns of the Glossary definition are met. If you are uncertain, treat the move as a partial merger for PI purposes and disclose accordingly.
How Apex helps
Apex's experience handling PI during law firm merger and acquisition events covers:
- Pre-deal disclosure pack assembly from the seller's side
- Pre-deal indicative engagement with the buyer's insurer
- Clause 5.5 election analysis and run-off structuring where the predecessor entity is being wound up
- Combined-entity renewal preparation with claims-history narrative
If you are contemplating a merger, acquisition, or significant structural change, talk to your named Apex broker early in the deal process. The earlier the PI workstream starts, the cleaner the outcome.
Upload your current Statement of Fact and existing policy schedule to proposal.apexinsurancebrokers.co.uk/commercial with a note describing the proposed transaction, and your named broker will be in touch.