Marine reinsurance: treaty, facultative and excess of loss explained
Understand how marine insurers use reinsurance, with worked quota-share and excess-of-loss examples, a clear contract map and the limits of risk transfer.
On this page
Reinsurance transfers an agreed part of an insurer’s risk to another insurer under a separate contract. Facultative and treaty describe the business accepted; proportional and excess-of-loss structures describe financial participation. Neither changes the assured’s policy into a direct claim against every reinsurer.
What you will learn
- Separate the original insurance relationship from the reinsurance relationship.
- Distinguish facultative and treaty arrangements from proportional and non-proportional participation.
- Calculate simplified quota-share and excess-of-loss recoveries and explain the remaining exposure.
The insurer has accepted a risk. Must it keep all of it?
A marine insurer agrees to cover a valuable shipment. The policyholder sees one insurance relationship, but the insurer may have arranged protection for part of the financial exposure it has accepted. A second contract sits behind the first.
Reinsurance is insurance purchased by an insurer for an agreed part of its own insurance risk. The insurer transferring that risk is the cedant, also called the ceding insurer or reinsured. The accepting party is the reinsurer. The contract defines the business and losses involved, the financial participation and the conditions of recovery.
This guide concerns ordinary indemnity reinsurance, using fictional marine examples. It explains the mechanism rather than the accounting treatment of every arrangement, regulatory capital relief or the wording needed for an actual placement.
Two contracts, with different parties
Consider three invented businesses. Meridian Imports insures its goods with Harbour Marine Insurance. Harbour then reinsures part of its exposure with Estuary Re.
Harbour remains responsible for its obligations to Meridian under the cargo policy. Its purchase of reinsurance does not automatically enlarge Meridian’s policy limit, remove its deductible or substitute Estuary Re as the direct insurer.
Special contractual arrangements, insolvency and the relevant law can require a different analysis. But for this ordinary example, a delay in Harbour’s collection from Estuary Re is a separate issue from deciding what Harbour owes under Meridian’s policy. A reinsurance recovery belongs to the insurer’s financial arrangements; it is not another cargo policy held by the importer.
This is also different from several insurers each subscribing a direct share of the original policy. The parties and contracts must be mapped before percentages can be interpreted.
Why marine insurers use reinsurance
An insurer may want to accept business whose full exposure would exceed the amount it wishes to retain. Reinsurance can support that capacity, reduce volatility or protect against unusually severe losses. It comes with a price and contractual boundaries; it does not make the underlying operation safer by itself.
Marine exposure also accumulates. A vessel can carry many separately insured consignments, and a port casualty can involve goods from several policyholders. An account that looks diversified by customer may still be concentrated by ship, location or event.
Those patterns connect reinsurance to marine underwriting. The insurer needs to understand what it has accepted before deciding how much to retain and what protection to buy. A reinsurer examining a portfolio likewise needs useful exposure and claims-record information, rather than a premium total on its own.
Facultative and treaty describe how business is accepted
Facultative reinsurance generally involves consideration and agreement for an identified individual risk. For example, an insurer may seek a separately negotiated participation for an unusual project-cargo shipment.
Treaty reinsurance provides an agreed framework for a defined class or portfolio of business. Risks satisfying that framework can enter without negotiating a new acceptance for each one. “Automatic” therefore means automatic within the terms, limits and exclusions, not unrestricted cover for everything the insurer writes.
Hybrid arrangements exist, so these are useful starting distinctions rather than labels that eliminate the need to read the agreement. A marine portfolio might use treaty protection and separate facultative arrangements for particular exposures.
Neither term tells the reader whether losses are shared by a percentage or by a layer. That is a second classification.
Proportional and excess-of-loss describe financial participation
| Question | Main distinction | Marine illustration |
|---|---|---|
| How does business enter the arrangement? | Facultative or treaty | One negotiated cargo risk, or qualifying business within an agreed cargo portfolio |
| How is the financial exposure shared? | Proportional or non-proportional | An agreed share of covered premiums/losses, or cover above a defined loss attachment |
Both facultative and treaty arrangements can be proportional or non-proportional. Treating “treaty” as another name for quota share, or “facultative” as another name for excess of loss, confuses the two questions.
Under a quota-share arrangement, a fixed agreed percentage of the covered business is ceded, with corresponding participation in premiums and losses on the contractual basis. Commissions and other accounting provisions also matter. Other proportional structures exist; quota share is the example used below.
Under excess of loss, the protection responds to qualifying loss above a stated attachment, up to the layer limit. The agreement must say whether that test operates per risk, per event or on an aggregate basis. Its premium is separately agreed; it is not simply the same percentage of original premium as a hypothetical recovery.
Worked example: a 40% quota share
All figures are invented. Assume an agreed cargo account is wholly eligible for a 40% quota-share treaty, with £200,000 relevant original premium and a £750,000 covered loss. Assume sufficient limits and exclude commissions, expenses, taxes, other reinsurance and collection difficulties.
| Item | Reinsurer: 40% | Cedant: 60% |
|---|---|---|
| Premium before the excluded adjustments | £80,000 | £120,000 |
| Covered loss | £300,000 | £450,000 |
The reinsurer’s loss participation is 40% × £750,000 = £300,000. Harbour’s remaining loss is £450,000. Harbour’s obligation under the original insurance is still assessed on that policy; Meridian does not become responsible for a 40% uninsured gap because its insurer has ceded that share.
The premium row is equally deliberate. A quota share transfers a defined slice of business rather than supplying free protection for the largest claims. In practice, a ceding commission can affect the premium accounting and economics. Omitting it makes the arithmetic easier, not a complete profitability assessment.
Worked example: £500,000 excess of £150,000
Now consider a separate per-risk excess-of-loss arrangement, not an additional protection stacked onto the quota-share example. Its layer limit is £500,000, attaching above £150,000 of the relevant insurer loss. The layer is fully exhausted at £650,000 of that loss.
Each row below is an independent example. The loss is the amount relevant to this insurer and this reinsurance layer, after the original assured’s deductible where applicable. Assume full participation in the layer, no other reinsurance, and no expense, reinstatement or aggregate-exhaustion complications.
| Relevant covered loss | Recovery from this layer | Cedant’s remaining loss |
|---|---|---|
| £75,000 | £0 | £75,000 |
| £400,000 | £250,000 | £150,000 |
| £900,000 | £500,000 | £400,000 |
For the middle row, £400,000 − £150,000 = £250,000, within the £500,000 layer. For the last row, the loss above attachment is £750,000, but the layer pays no more than £500,000. The cedant therefore keeps £150,000 below the layer plus £250,000 above it: £400,000 in total.
The attachment is not a promise that the insurer can never lose more than £150,000. Loss above the top of the layer remains unless another agreed protection responds. Nor can three separate cargo claims simply be combined into one per-risk recovery: aggregation depends on the actual contract.
A recoverable amount is not the same as collected cash
The insurer must match a loss to the reinsured business, period, exclusions, limits and claims provisions. A large original insurance claim does not by itself establish an equally large reinsurance recovery. A description such as “gross loss” or “net retention” needs a stated basis, especially where several protections interact.
Reinsurer performance creates another exposure. Credit quality, concentration, security and the timing of recovery can matter even where the arithmetic is clear. The PRA’s UK supervisory guidance is one example of formal attention to these risks; its particular expectations should not be treated as worldwide contract terms.
A reinsurer may itself buy retrocession, passing an agreed part of its assumed risk onward. That adds another contract, rather than making the original assured a party to an expanding chain of policies.
The practical reading habit is to ask who owes whom, what business qualifies, how the participation operates and which exposure remains. Once those questions are clear, reinsurance becomes a set of understandable agreements rather than a percentage floating behind the original policy.
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