In chapter 3 through 8 we developed a theory for the analysis of financial benefits contingent on the time of death of a single life. We can extend this theory to benefits involving several lives. An application of this extension commonly found in pension plans is the joint-and-survivor annuity option. Other applications of multiple life actuarial calculations are common. In estate and gift taxation, for example, the investment income from a trust can be paid to a group of heirs as long as at least one of the group survives. Upon the last death, the principal from the trust is to be donated to a qualified charitable institution.