Definition
A tontine structure is a mortality pool in which survivors receive redistributed shares of the capital of deceased members, used in the Longevity Standard framework as the structural reference for all pooled lifetime income arrangements.
Why it matters
The tontine structure names the mechanism that distinguishes pooled lifetime income from both solo drawdown and insurance: capital is not extinguished at death, as it is when an insurer bears the risk, and it is not retained by the estate, as it is in self-managed drawdown. It is redistributed among survivors. Understanding this mechanism is what makes the pooling multiplier legible — the extra income in a longevity pool comes from somewhere, and the tontine structure names where.
How it works
In a tontine structure, each member contributes capital to a shared pool. When a member dies, that member's remaining share is not returned to their estate. Instead, it is reallocated to surviving members according to the pool's governing redistribution rule. The income each survivor receives therefore increases over time as the pool contracts — more redistribution is divided among fewer survivors. This mechanism is the structural foundation for mortality credits: each redistribution event generates a mortality credit for surviving members. The tontine structure is distinct from the frictionless tontine (the zero-load version used as the cost-of-income benchmark) and from commercial tontine products where they exist — both are specific implementations of the underlying tontine structure.
In practice
For an individual evaluating pooled lifetime income arrangements, understanding the tontine structure resolves a common confusion: pooling is not insurance in disguise. An insurer takes your capital and assumes the longevity risk in exchange for a guaranteed payment. A tontine structure keeps capital within the pool and distributes the mortality credit directly to survivors. The two mechanisms produce different cost structures, different counterparty exposures, and different obligations on the party bearing the risk. When an arrangement is marketed as a tontine, a direct pool, or a group self-annuitization scheme, the tontine structure is the mechanism to look for: capital that does not leave the pool at death, a redistribution rule governing how it flows to survivors, and no insurer guarantee standing between the pool and its members.
In the Longevity Standard Framework
The tontine structure is the pooled-risk analytical reference in the Longevity Standard framework. It establishes the mechanism through which mortality credits are generated and distributed. The frictionless tontine claim profile and the frictionless pool (one of the four core terms of the Longevity Standard framework) both rest on the tontine structure as their underlying mechanism.
Related terms
- Frictionless pool
- Pooling baseline
- Mortality credit
- Mortality-contingent redistribution
- Tontine
- Tontine payout mechanics
- Longevity pool
- Risk sharing