The insurance plan (or other payer) that provides payment coverage for residual insured expenses after applying the primary payer's coverage.
When coordinating benefits, the health plan that pays benefits only after the primary payer has paid its full benefits. When an FEHB fee-for-service plan is the secondary payer, it will pay the lesser of: its benefits in full, or an amount that when added to the benefits payable by the primary payer, equals 100% of covered charges.
An insurance policy, plan, or program that pays benefits after the primary insurer has paid its share of the claim. This could be Medicare, Medicaid, or other health insurance, depending on the situation.