First death is what most couples are sold. The policy pays out when the first of the two dies, and then ends. It is the usual choice where the money is needed by the survivor: clearing a mortgage, replacing an income, raising children.

Second death pays out only when both have died. It is no use to a surviving partner, and it is not meant to be: its normal purpose is estate planning, providing a lump sum to meet an inheritance tax bill at the point the estate actually passes to the children. Second death cover is usually written as whole of life rather than term, because the need does not expire.

This is the part rarely volunteered at the point of sale. A first-death joint policy pays out once and then stops. The survivor, often a parent with dependent children and now the only earner, is left with no life cover at all, at an older age and possibly in worse health than when the original policy was written. Replacing it is expensive if it is possible at all.

Two single policies pay out twice if both die during the term, and the second policy continues untouched after the first pays. The cost difference is frequently smaller than people assume, often in the region of 10–20% more than a joint policy rather than double, because much of the premium reflects each life's individual risk either way.

A joint policy is a single contract on two lives. It cannot simply be split into two policies if the relationship ends. In practice the usual outcome is that the policy is cancelled and both parties apply again individually, years older and having to disclose any health condition that has arisen since.

Two single policies from the outset avoid the problem entirely: each person keeps their own cover, at the price and health basis originally agreed. Given how many long-term policies outlast the relationships they were bought during, this is a practical consideration rather than a pessimistic one.