Category: Claims handling · Reviewed by Al Jabbar, Broker · Specialist Risks · Last reviewed 2026-06-11
Originating-cause analysis is the application of an aggregation clause that turns on the existence of a single underlying root cause — typically broader than “event” or “occurrence” — to determine whether multiple claims should be treated as one.
“Originating cause” is one of the broadest aggregating concepts in English insurance wording. It captures not just a single event or occurrence, but the underlying root cause from which a chain of consequences flowed. It is most commonly used in older reinsurance treaty wordings and in some bespoke primary covers; the SRA Minimum Terms wording uses “common originating cause” as one of four aggregating limbs.
The leading authority is Axa Reinsurance (UK) plc v Field [1996] 1 WLR 1026, in which the House of Lords analysed the meaning of “originating cause” and contrasted it with the narrower “event”. Lord Mustill described originating cause as the source from which the loss-producing events flowed; it could be a single state of affairs that gave rise to many incidents over time.
Axa v Field is the foundational authority. The House of Lords held that “originating cause” is wider than “event” or “occurrence” — it captures the underlying source of multiple consequences, not just the immediate proximate cause. A regulatory failing that produced multiple mis-selling complaints can be a single originating cause; a defective design that produced multiple structural failures across a development can be a single originating cause.
Subsequent authorities have refined the analysis:
The Court of Appeal in Spire applied broad originating-cause logic to aggregate hundreds of claims arising from the conduct of a single surgeon over many years. The decision is widely cited as evidence that originating-cause wording can produce expansive aggregation outcomes where the underlying source of the claims is itself a single phenomenon (in Spire, the surgeon’s pattern of conduct).
Originating-cause analysis asks the same fundamental question as series-clause analysis but applies a broader test. Where a series clause asks whether the claims are “related” to each other through some dependent factual link, an originating-cause clause asks whether they share a single underlying root cause — even if the immediate triggers and the affected parties differ widely.
The analytical sequence: identify the multiple claims; identify the originating-cause wording; ask whether there is a single underlying cause that produced all of them; if so, aggregate.
Typical originating causes that have produced aggregation outcomes include:
The breadth of the wording cuts both ways. From the insurer’s perspective, originating-cause aggregation may cap the loss at one limit. From the insured’s perspective, the same aggregation may consume the entire annual cover on what should logically be many separate matters.
Originating-cause analysis interacts with the trigger and limit structures of the policy. Aggregation only matters where multiple claims would otherwise consume multiple limits. If the policy has unlimited cover or where the aggregate cap is well above the loss, aggregation is academic.
In reinsurance, originating-cause aggregation is critical for the cedant’s net retention. A reinsurance treaty written on an “any one event” basis is much narrower than one written on an “originating cause” basis; the cedant’s retention applies many times under the former and once under the latter.
“Single source” wording: synonymous with originating cause in some wordings.
“Common cause” wording: similar to originating cause but emphasising the shared nature of the cause rather than its primacy.
“Root cause” wording: similar but with a stronger implication that the cause is the underlying explanation rather than the proximate trigger.
“Common origin” or “single origin” wording: variants found in some Lloyd’s-market wordings.
The choice of wording materially affects the breadth of aggregation. “Event” is narrowest; “occurrence” is broader; “cause” is broader still; “originating cause” is broadest.
A construction surveyor used a single defective methodology for assessing reinforced concrete across multiple project surveys over four years. Twenty-two separate projects failed structural inspection following the methodology error, with combined remediation costs of £14m. The surveyor’s PI policy has £5m per claim, £15m aggregate cover, and an “originating cause” aggregation clause derived from the Axa v Field line of authority. The originating cause is the defective methodology — a single underlying root cause that produced all twenty-two failures. The aggregation clause is engaged: all twenty-two claims aggregate as one. One £5m limit applies; £9m of the loss is uninsured. The surveyor’s E&O deductible applies once, not twenty-two times. The reinsurance treaty above the surveyor’s primary cover also aggregates the claim as a single cession, recovering one event from the treaty rather than twenty-two.
By Matt Bartlett, Director, on 2026-06-11. Next review: 2026-12-11.
This entry is part of the Apex Insurance Wiki. Last reviewed by Matt Bartlett on 2026-06-11. Apex Insurance Brokers Limited, FCA FRN 724952, Companies House 07014570. Not regulated advice — consult your broker on your specific position.
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