Standing reinsurance arrangement covering a defined class of business.
Treaty reinsurance is reinsurance arranged for a defined class or portfolio of business, so that covered risks in that portfolio are shared automatically according to the treaty terms.
The important idea is automation. Once the treaty is in place, qualifying risks are ceded according to the treaty rules without the insurer having to negotiate every individual policy separately.
Treaty reinsurance matters because it is how insurers support an ongoing book of business rather than just isolated exceptions. It is central to portfolio management, catastrophe planning, growth, and capital efficiency.
For a Canadian insurer, a treaty can support entire classes of property, casualty, auto, specialty, or catastrophe-exposed business. That allows the insurer to write a consistent portfolio without having to seek separate approval from a reinsurer for each ordinary policy inside that portfolio.
Instead of reviewing each risk one by one, the reinsurer agrees in advance to take part of a defined stream of business that fits the treaty’s scope, limits, exclusions, and reporting rules. The treaty may be structured:
That is why treaty reinsurance is usually contrasted with facultative reinsurance, where a particular risk is submitted separately for case-by-case review.
The treaty does not mean every risk is automatically recoverable without question. The agreement still defines what business qualifies, how bordereaux and reporting work, what exclusions apply, what retention the ceding insurer keeps, and how losses are allocated.
An insurer with a large portfolio of commercial property policies may rely on a property-catastrophe treaty so that a major wildfire event does not sit entirely on the insurer’s own books.
Treaty reinsurance does not mean every risk is treated identically. The treaty still defines what business qualifies, what exclusions apply, and how recoveries are calculated.
It is also not visible to the retail policyholder in the same way an endorsement or deductible is. It is a behind-the-scenes insurer-level arrangement.
Another common mistake is assuming treaty reinsurance removes the need for underwriting discipline. It does not. The ceding insurer still has to write business within the treaty rules and manage its retained net position responsibly.
Treaty language is technical and highly negotiated. The plain-language concept here is only the starting point for understanding the structure.