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Aggregation in the SRA Minimum Terms — clause 2.5 explained

Every solicitors' primary professional indemnity policy in England and Wales must comply with the SRA Minimum Terms and Conditions ("MTC"). Clause 2.5 of the MTC is the aggregation clause. It is short — fewer than 150 words — but it is the source of more disputes between solicitors and PI insurers than any other clause. This article explains what clause 2.5 says, how it has been construed (notably in AIG v Woodman [2017] UKSC 18), and what solicitors should do about it.

This article is Spoke 4 of the Apex hub on aggregation and series clauses in PI insurance.

Plain English explanation

The SRA Minimum Terms set the floor of cover that a solicitors' primary PI policy must provide. They do not set the ceiling — insurers can offer wider cover, and many do. But they cannot offer narrower cover on points the MTC addresses. Aggregation is one of those points. Clause 2.5 allows insurers to aggregate claims into one for the purposes of the £2 million (or £3 million for incorporated firms) minimum limit, provided the aggregation is no wider than the four triggers the MTC permits.

Those four triggers — "one act or omission"; "one series of related acts or omissions"; "the same act or omission in a series of related matters or transactions"; "similar acts or omissions in a series of related matters or transactions" — form a ladder. The first is narrow, the fourth is broad. An insurer arguing aggregation only needs to win on one rung. A solicitor resisting aggregation needs to defeat the argument on all four.

The clause: what it says

The full text of clause 2.5(a) of the SRA Minimum Terms (effective 1 November 2014 onwards, with text updated through the Solicitors Indemnity Insurance Rules) reads:

"2.5 One Claim (a) The insurance may provide that, when considering what may be regarded as one Claim for the purposes of: (i) the limits contemplated by clauses 2.1 and 2.3; (ii) the excesses contemplated by clause 2.2; and (iii) the Defence Costs provisions of clause 1.3, all Claims against any one or more Insured arising from: (A) one act or omission; (B) one series of related acts or omissions; (C) the same act or omission in a series of related matters or transactions; (D) similar acts or omissions in a series of related matters or transactions, will be regarded as one Claim."

The clause is permissive — "may provide" — meaning an insurer can aggregate but does not have to. In practice every primary policy includes a corresponding aggregation provision in the wording.

Clause 2.5(b) deals with the proceeds of the policy on aggregation, and clause 2.5(c) deals with the position of "any Insured" for the purposes of aggregation.

The four rungs of the aggregation ladder

Rung A — "one act or omission". The narrowest trigger. A single act or single omission by the firm. A solicitor who, in one letter, releases all the escrow money in one transaction commits one omission. The same solicitor who releases escrow money on twenty different files in twenty different transactions commits twenty omissions, even if the omissions are identical. Rung A would not aggregate them.

Rung B — "one series of related acts or omissions". A series of acts or omissions that are themselves related. This rung does not require the underlying matters or transactions to be related — only the acts or omissions. A solicitor who, in twenty letters, signs off twenty release authorities on the back of a single mistaken belief that no security needed to be taken commits a "series of related" omissions. Rung B aggregates them. This rung is used by insurers when the matters do not look related but the firm's conduct does.

Rung C — "the same act or omission in a series of related matters or transactions". Combines requirements from rungs A and rung D. There must be a single act or omission, and that act or omission must take place in matters or transactions that are themselves a related series. Narrower than rung D because the act or omission must be the same, not merely similar.

Rung D — "similar acts or omissions in a series of related matters or transactions". The broadest rung. Similar (not identical) acts or omissions, in a related series of matters or transactions. This is the rung the Supreme Court construed in AIG v Woodman. The same security failure across two property schemes was a "similar omission"; the schemes themselves had to be "related" for the rung to apply.

In practice, most aggregation disputes proceed under rung D, because it is the broadest and the easiest to plead. Where rung D fails, insurers fall back to rung C, then to rung B. Rung A is rarely useful to insurers because few real-world clusters arise from literally one act or omission.

The post-Woodman position

The Supreme Court in AIG v Woodman set the modern test for rung D: matters or transactions are "related" if, viewed objectively and in the round, they are connected in a "real" way. The reasoning travels naturally to rung C (which uses the same "series of related matters or transactions" phrase) and informs rungs A and B by analogy.

Three lessons from the post-Woodman application of clause 2.5 to solicitors' claims:

Property scheme work is the highest-risk aggregation exposure. Common scheme, common trust deed, common security failure — all readily satisfy rung D under Woodman. Firms doing scheme work for institutional investors, syndicated property funds, BTL portfolios or development funds should expect aggregation across the entire scheme and should size limits accordingly.

Volume conveyancing for a single developer is the next-highest. A series of conveyances for the same developer on the same estate, using the same documents, with the same title issue, will be a "series of related matters or transactions". Conveyancing fraud sweeps where the firm has been deceived by the same fraudster across many transactions raise distinct issues — see Spoke 10.

Will-writing and probate aggregation is usually fragmented. Each will is its own instruction, each estate is its own administration. Even where a solicitor consistently makes the same drafting error, the underlying matters are independent — different testator, different beneficiaries, different estate. Rung D will usually fail because the matters are not related. Rung B may still apply if the omissions are themselves a related series.

Worked example with numbers

Take a solicitor with the SRA minimum £2 million per-claim limit (incorporated practice — £3 million minimum), a £25,000 excess, and one of the following exposure patterns.

Pattern 1 — Scheme failure (rung D aggregation). Acted as escrow agent for 100 investors in a single property scheme. Released money without proper security. Scheme fails. 100 investors claim. Total loss £6 million.

One aggregated claim under rung D. £3 million limit. £25,000 excess. Insurer pays £2.975 million; firm pays £25,000 + £3.025 million limit shortfall = £3.05 million.
Compare without aggregation: 100 individual claims, each capped at £3 million per claim limit. Total insurer payout £6 million. Firm pays 100 × £25,000 excesses = £2.5 million.
Net effect of aggregation: firm worse off by approximately £550,000 because the limit cuts in.

Pattern 2 — Conveyancing series for one developer (rung D aggregation). 40 conveyances for the same developer on the same estate, common title defect discovered. 40 buyers claim £40,000 each. Total loss £1.6 million.

One aggregated claim under rung D. £3 million limit. £25,000 excess. Insurer pays £1.575 million; firm pays £25,000. Total firm cost £25,000.
Compare without aggregation: 40 individual claims, each within the £3 million limit. Insurer pays 40 × £15,000 (£40k less £25k excess) = £600,000. Firm pays 40 × £25,000 = £1 million in excesses. Insurer separately picks up the rest — but only above excess, so firm carries the full £1 million.
Net effect of aggregation: firm better off by approximately £975,000. Aggregation here is the policyholder's friend because it unifies the excess.

Pattern 3 — Will-writing series (probably no aggregation under rung D, possible rung B). Solicitor mistakenly includes a residuary trust in 30 wills over five years. 30 estates affected. Probate complications and litigation cost £15,000 per estate. Total loss £450,000.

If no aggregation: 30 × £25,000 excess = £750,000 in excesses — more than the total loss. Insurer effectively pays nothing because most or all claims are below excess.
If rung B aggregation: one aggregated claim, £25,000 excess, insurer pays the rest within limit.
Net effect: the policyholder wants aggregation here and will argue rung B (related omissions). The insurer may argue against (each will is its own decision, no related series of omissions). The bargaining position runs both ways depending on the facts.

These three patterns illustrate why aggregation under clause 2.5 cannot be assessed as "good" or "bad" in the abstract. It is a tool. Its effect on you depends on the cluster shape.

Sector implications within the profession

Property and conveyancing. Highest aggregation exposure. See above and Spoke 10.

Wills, trusts and probate. Mixed. Individual estates are usually independent matters, but pattern-of-conduct errors can attract rung B.

Family law. Generally individual matters. Aggregation rarely operative unless a particular methodology is challenged across many cases.

Commercial transactions. Mixed. A series of transactions for the same client on the same matter (e.g. tranches of a financing) will aggregate. Independent commercial transactions across different clients will not.

Litigation. Generally individual matters. Each piece of litigation is its own engagement.

Group conveyancing for institutional lenders. Highly aggregating. Common documentation, common lender, common procedure — rung D will usually apply across the portfolio.

What this means for your firm

Map your aggregation exposures and disclose them. The fair presentation duty under Insurance Act 2015 section 3 requires disclosure of material circumstances, including cluster-level features. Brokers should be asked to advise on what to disclose. See our solicitors PI proposal completion guide.

Size the limit against the worst-case aggregated cluster. The £2 million (or £3 million) minimum is not enough for any firm doing scheme work or volume conveyancing. Excess layers from £2 million up to £10 million, £25 million or higher are routine for firms with concentrated exposures.

Notify by cluster. When a single complaint suggests cluster-level issues, notify the cluster. Use language like "circumstances affecting [scheme name] / [developer name] / [type of transaction]".

Take coverage advice early. Aggregation disputes are resolvable in the firm's favour with the right notification and the right factual development. Get external coverage counsel involved as soon as a cluster looks credible.

Stress-test the run-off scenario. Run-off cover under SRA Minimum Terms has a single aggregate over six years. Aggregation under clause 2.5 can exhaust the run-off aggregate in year one. Plan accordingly when retiring partners or merging.

How the SRA-set wording differs from other professions

Most other professional bodies (RICS, ICAEW, ARB) do not prescribe specific aggregation wording. Their minimum-terms rules require "adequate" cover and impose certain qualitative restrictions, but the aggregation drafting is left to the market. The result is that solicitors have the most uniform aggregation wording in the UK PI market (because the SRA prescribes it), while surveyors, accountants, architects and IFAs operate with a range of insurer-specific aggregation language.

The implication for solicitors is that almost every PI dispute will turn on the same four rungs. The implication for other professions — covered in Spokes 5–7 — is that aggregation analysis varies more, and reviewing the specific policy wording at renewal matters more.

FAQs

Q1. Can I have an SRA-compliant policy with no aggregation clause? You could, but you would not get one in the market. Insurers will not write the risk without aggregation because the loss models depend on it. The MTC permits aggregation up to the four-rung ladder; the market uses that permission.

Q2. Can the insurer aggregate more widely than clause 2.5 allows? No. The MTC sets the maximum aggregation. Wider aggregation in the wording would be unenforceable to the extent it exceeded the MTC permission.

Q3. Does clause 2.5 apply to the excess as well as the limit? Clause 2.5 expressly applies to the limit and to the excess (clause 2.5(a)(ii) references the excesses in clause 2.2). The policy wording usually applies the same aggregation rules to both.

Q4. What is the difference between rung C and rung D? Rung C aggregates the same act or omission across a related series of matters or transactions. Rung D aggregates similar acts or omissions across a related series. "Similar" is a lower bar than "same", so rung D is wider.

Q5. Does aggregation apply to defence costs? Yes — clause 2.5(a)(iii) extends the aggregation regime to defence costs. Defence costs are usually outside the limit under SRA Minimum Terms but inside the aggregation count for the purposes of counting how many claims there are.

Q6. What happens with the £3 million limit for incorporated firms? The MTC requires £3 million per claim for any incorporated practice. Aggregation under clause 2.5 applies the same way — claims aggregating into one claim share that £3 million limit.

Q7. How does clause 2.5 interact with the SRA's compulsory run-off cover? Run-off cover is governed by clauses 1.3 and 5 of the MTC. It carries a single aggregate over the six-year run-off period. Aggregation under clause 2.5 applies in run-off as it does in the active policy.

Q8. Can a partner argue that their own acts or omissions should not aggregate with another partner's? No. Clause 2.5(a) aggregates "all Claims against any one or more Insured". Partners' acts or omissions aggregate together where the cluster otherwise satisfies the relevant rung.

Q9. Is the clause likely to be amended? The SRA reviews the MTC periodically. There has been industry pressure to revisit the £2 million / £3 million floor, but no current proposal to amend the aggregation language itself. Watch the SRA's consultations.

Q10. What is the single most useful thing I can do about clause 2.5 in 2026? Buy limit. The aggregation language is what it is. The only durable mitigation is to ensure the aggregated limit available to your worst-case cluster is large enough to cover it.

Aggregation under SRA Minimum Terms clause 2.5