Category: Claims handling · Reviewed by Taylor Watts, Broker · New Business · Last reviewed 2026-06-11
Contribution is the equitable doctrine by which an insurer that has paid more than its rateable share of a loss to which two or more insurers are liable can recover from the other insurer(s) the excess paid.
Where the same insured holds multiple policies that respond to the same loss — for example, a primary PI policy plus an excess D&O policy where the claim falls within both — both insurers may be liable to indemnify. The doctrine of contribution provides that, between them, the insurers share the burden rateably, and an insurer that has paid more than its share can recover the difference from the others.
Contribution is closely related to (but distinct from) the doctrine of double insurance. Double insurance is the situation; contribution is the remedy.
The doctrine is judge-made. The leading authorities include:
The principles:
The Civil Liability (Contribution) Act 1978 governs contribution between tortfeasors. Contribution between insurers operates in equity and is conceptually distinct, though the 1978 Act may apply where the insurers are themselves liable to a common third party.
Contribution analysis runs through:
First, identify the multiple policies that respond. Both must cover the same loss, the same insured and the same interest. If one of these elements diverges (e.g., different insureds, different perils, different property), contribution does not apply.
Second, identify the operative “other insurance” clauses in each policy. These typically take three forms:
Third, resolve any conflict between the clauses. The classical analysis is that where two policies both contain escape clauses, the courts will treat both as ineffective (since each would exclude the other) and apply rateable contribution. Where one contains an escape and one contains an excess clause, the policy without the escape will respond first. The case law (especially Drake v Provincial) provides detailed guidance.
Fourth, calculate the rateable share. The standard method is the “maximum liability” method: each insurer’s contribution is proportional to its policy limit. Alternative methods (the “independent liability” method) are sometimes used in specific contexts.
Fifth, settle inter-insurer accounts. In practice, the insurer that has paid the loss will seek reimbursement from the other(s) under the contribution doctrine. Disputes between insurers about contribution may go to ARIAS arbitration or to court.
For the insured, contribution is generally invisible. The insured is paid the loss by one insurer (typically the leader) and the inter-insurer accounting happens behind the scenes. The insured’s only exposure is where one insurer is insolvent — the surviving insurer may bear more than its rateable share.
“Vertical” contribution between primary and excess layers: typically not contribution but exhaustion, with the excess responding only after the primary is exhausted.
“Horizontal” contribution between concurrent primary layers: the classic contribution situation.
“Layered” contribution where multiple parallel programmes overlap: complex analysis applying contribution principles within each layer.
“International” contribution across multi-jurisdictional programmes: governed by choice of law and the differing approaches of various legal systems to contribution.
A multinational corporate group holds a £20m global D&O programme with insurer A as primary and a separate UK-domestic D&O policy with insurer B providing £10m of coverage to the same insured directors for UK-located claims. A £15m UK enforcement matter triggers both policies.
Insurer A’s primary policy contains a rateable-proportion clause. Insurer B’s policy contains an “other insurance” clause that purports to make B’s cover excess of any other applicable insurance.
Analysis: the clauses conflict (B says it is excess; A says rateable proportion). Following Drake v Provincial, the court would likely resolve the conflict by giving both policies effective scope: B’s excess clause is honoured first (so B does not pay until A’s £20m primary is exhausted). The £15m settlement is paid by A alone; no contribution from B.
Alternative scenario: if both policies contained rateable proportion clauses, contribution would apply. Maximum liability for each: A £20m, B £10m. Total £30m. Rateable share: A pays £15m × (20/30) = £10m; B pays £15m × (10/30) = £5m. Both insurers’ deductibles applied proportionately.
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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