Category: Reinsurance structures · Reviewed by Amy Price, Account Executive · Last reviewed 2026-06-05
A surplus line, in the context of surplus treaty reinsurance, is one multiple of the cedant’s retention. A 10-line first surplus treaty provides ten multiples of the retention as treaty capacity. A second or third surplus may be placed above the first to extend total capacity for the largest risks.
Category: Reinsurance structures Also known as: second surplus, third surplus, line Related concepts: surplus treaty reinsurance, proportional reinsurance
The ‘line’ is the unit of cession capacity in a surplus treaty. The cedant’s retention defines the size of a line; the treaty defines the number of lines available. A treaty offering ‘10 lines of £2m’ provides £20m of capacity above the retention. A second surplus might offer a further 10 lines, giving total capacity (cedant + first surplus + second surplus) of £42m on any single risk.
In some markets, particularly continental Europe, the term ‘line’ is also used for the proportional share of an individual placement that a reinsurer takes — a reinsurer might take a ‘line’ of 5 per cent on a facultative placement.
Surplus line structures are documented under the Market Reform Contract format. The legal effect is the same as for any proportional reinsurance: the reinsurer assumes its lines’ share of premium and losses on each cession.
In practice the surplus line is a means of structuring layered proportional capacity for very large risks. A cedant with a £2m retention might place:
Each surplus operates as a separate treaty with its own panel of reinsurers, commission terms and conditions. The cessions are applied sequentially: first the retention, then first surplus, then second surplus, then any balance.
For the cedant, layering surplus lines is a way to obtain larger aggregate capacity than a single market would provide and to diversify the reinsurance panel across multiple treaties.
An illustrative example: a UK property insurer has a £1m retention. Its 2024 reinsurance structure is:
On a £15m sum insured risk: retention takes £1m (6.7 per cent), first surplus takes £9m (60 per cent), second surplus takes £5m (33.3 per cent of the risk, against treaty capacity of £10m).
This entry is part of the Apex Insurance Wiki. Last reviewed by Matt Bartlett on 2026-06-05. Next review: 2026-12-05.
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