Definition
Coinsurance, in the reinsurance context, is a full-risk-transfer structure in which the reinsurer assumes a defined share of the policies in a block of business as if it had written them directly, taking a corresponding share of premium, claims, policy reserves, and the assets that support those reserves.
Why it matters
For a contract owner, coinsurance changes the structural backing of the original arrangement: a portion of the assets supporting the contract is held and managed by the reinsurer rather than by the original carrier, even though the contract itself does not move. Naming coinsurance directly is part of seeing where the assets that back a lifetime income arrangement actually sit.
How it works
In a coinsurance arrangement, the ceding carrier transfers a defined percentage of the policies in a block — premium, claims, reserves, and the supporting assets — to the reinsurer. The reinsurer is then in substantially the same economic position as if it had directly issued that share of the policies, with the reserves and the assets sitting on its balance sheet and being managed within its asset-liability framework. The ceding carrier continues to administer the contracts with the original contract owners and remains contractually liable to them; the reinsurer is liable to the ceding carrier under the reinsurance treaty. A stylized illustration: if a carrier cedes 30% of a block of fixed annuities to a reinsurer under a coinsurance treaty, the reinsurer receives 30% of premium, holds 30% of the reserves, manages the corresponding 30% of the supporting assets, and funds 30% of the contract payments as they arise.
In practice
For an individual holding or evaluating a commercial annuity, coinsurance does not appear in the contract documentation but is disclosed in the issuing carrier's statutory annual statement and discussed in financial strength rating commentary. The questions worth understanding are whether the block backing the contract has been substantially coinsured, to whom, and under what circumstances — particularly whether the reinsurer is affiliated with the ceding carrier or domiciled offshore, which changes the structural risk profile in ways the gross financial strength rating may not fully capture. For a plan fiduciary, the carrier's coinsurance program is part of carrier characterization. Most individuals will not investigate coinsurance in detail, but the framework for asking the question exists in the statutory filings and the rating-agency commentary.
In the Longevity Standard Framework
Coinsurance is supporting vocabulary in the Longevity Standard framework. In the framework's terms, coinsurance is the most complete form of reinsurance-based reassignment of an asset-backed claim's economic backing: the assets supporting the ceded share move to the reinsurer, the reinsurer's investment yield and asset-liability management practices govern those assets, and the embedded spread economics of the ceded contracts are accordingly governed by the reinsurer's regime rather than the ceding carrier's. The original contract owner's contractual claim against the ceding carrier is unchanged, but the underlying economic structure has shifted.
Related terms
- Reinsurance
- Modified coinsurance
- Funds withheld reinsurance
- Asset-backed claim
- General account
- Embedded spread
- Affiliated reinsurance
- Statutory accounting principles