What it means
Every insurance company faces the same structural problem: a run of bad luck can wipe out years of profit in a single quarter. Reinsurance solves it by sharing the risk with a larger, more diversified counterparty that can absorb losses spread across many territories and lines of business.
In return, the insurer hands over a slice of its premium income. There are two broad shapes.
Proportional reinsurance splits premiums and claims by a fixed percentage, so a 30% quota share means the reinsurer receives 30% of the premium and pays 30% of every claim. Non-proportional cover, usually called excess of loss, only responds once claims pass an agreed threshold, which makes it cheaper but leaves the insurer carrying the ordinary day to day losses.
For managers outside the insurance world, the commercial point is capital efficiency. Regulators require an insurer to hold capital against the risks sitting on its books, so ceding risk releases capital that can be used to write more business.
Reinsurance is therefore less a safety blanket than a financing tool. Proportional deals almost always include a ceding commission, a payment from the reinsurer back to the insurer that covers the cost of finding and administering the business.
This matters because the insurer keeps its acquisition costs funded on the ceded share while giving up the premium, which is where much of the economic benefit actually sits. The nuance that catches people out is credit risk.
Ceding a policy does not release the insurer from its promise to the policyholder, so if the reinsurer fails to pay, the original insurer still owes the claim in full. That is why finance teams monitor the credit rating and concentration of their reinsurance panel as closely as they monitor the price.
In practice
Real-world examples.
Example
A marine insurer is asked to cover a single container vessel worth $400,000,000, far more than it would ever risk alone. It writes the policy and immediately places 85% of it facultatively with three reinsurers, keeping a $60,000,000 net line that its capital comfortably supports.
Example
A motor insurer in a hurricane-exposed state buys excess of loss cover that pays anything above $25,000,000 of storm claims in a single event, up to $200,000,000. A severe season produces $90,000,000 of claims from one storm, so the insurer keeps $25,000,000 and recovers $65,000,000.
Example
A fast growing health insurer wants to triple the number of policies it sells but lacks the capital to back them. It cedes 50% of every policy under a quota share treaty, halving the capital it must hold per policy and funding growth without raising equity.
Think of it
“Reinsurance is insurance for insurers-spreading risk to other insurance companies.
Formula
Calculation
Ceded premium = gross written premium x quota share percentage
Net retained premium = gross written premium - ceded premium
A regional property insurer writes $50,000,000 of gross premium in a year and buys a 30% quota share treaty. Ceded premium = $50,000,000 x 0.30 = $15,000,000, leaving net retained premium of $50,000,000 - $15,000,000 = $35,000,000. The reinsurer pays a ceding commission of 25% on the ceded premium, which is $15,000,000 x 0.25 = $3,750,000 returned to the insurer.
Claims for the year come to $32,000,000. The reinsurer's share is $32,000,000 x 0.30 = $9,600,000, so the insurer's net claims are $32,000,000 - $9,600,000 = $22,400,000. The net loss ratio is $22,400,000 / $35,000,000 = 64%, identical to the gross ratio of $32,000,000 / $50,000,000 = 64%, which shows that on a proportional treaty the improvement comes from the $3,750,000 commission and the capital released, not from the loss sharing itself.Case study
Seen in the real world.
The following is an illustrative and entirely fictional example. Harbour Line Mutual, an invented regional insurer covering coastal small businesses, had grown its book to $80,000,000 of premium while buying only a thin layer of catastrophe cover, on the reasoning that its reserves had always been sufficient.
A single severe storm season in this fictional scenario produced $46,000,000 of claims against $80,000,000 of premium, and because Harbour Line retained almost all of it, the year's underwriting loss consumed roughly a third of its capital. The regulator restricted new business until the balance sheet recovered, which cost the firm two years of growth.
The illustrative lesson its board drew was that reinsurance is priced against the worst plausible year rather than the average one. Harbour Line restructured its programme around a 30% quota share plus an excess of loss layer, accepting a lower expected profit in exchange for a far narrower range of possible outcomes.
Watch out
Common mistakes.
- Assuming that ceding risk also cedes the legal obligation, when the original insurer still owes the policyholder in full if the reinsurer defaults.
- Judging a reinsurance programme purely on cost, ignoring the capital it releases and the volatility it removes from reported earnings.
- Treating quota share and excess of loss as interchangeable, when one shares every claim proportionally and the other only responds to large events.
Questions
People also ask.
Is reinsurance the same as a captive insurance arrangement?
No, a captive is an insurer owned by the business whose risks it covers, though captives themselves often buy reinsurance.
Who actually pays for reinsurance in the end?
The cost sits inside the premiums policyholders pay, so it is one of the reasons cover for catastrophe-exposed property is expensive.
Can an ordinary company buy reinsurance directly?
Not usually, because reinsurance is sold to licensed insurers; a company wanting similar protection buys excess layers of ordinary insurance instead.
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