Coordination of benefits (COB) is a provision that determines the sequencing of coverage when plan members and their dependents are eligible for benefits under more than one health care plan. One insurer is the primary payor, while the other is secondary. Families with two working adults may be covered by more than one health or dental plan. If the member’s primary plan doesn't pay the full amount of an expense, they can submit a claim to the other plan for the balance. In this way, the member can receive up to 100% of their expense.