A financial arrangement whereby a group of individuals each pay an initial lump sum to a controlling authority, who then returns a sum to them at an agreed interval, usually a year. When a member of the tontine dies, the payment that they would receive every period is instead divided amongst the surviving members. When no more members are alive the scheme ends.

A popular variant in fiction is that payments are not given out regularly, instead the last surviving member is entitled to the entirety of the initial investment.

Tontines are never used in the modern day, as they implicitly encourage the killing of the other participants and are inherently uncertain.