What does "coinsurance" involve in health insurance?

Coinsurance in health insurance refers to the arrangement where, after the insured has met their deductible, they are responsible for a certain percentage of the costs of covered medical services. For example, if the coinsurance is set at 20%, the insured would pay 20% of the medical bills, while the insurer covers the remaining 80%. This cost-sharing mechanism helps to involve the insured in their healthcare spending, as they are encouraged to consider the costs of services since they share a portion of the payment.

The other options suggest different payment structures that do not accurately reflect the concept of coinsurance. A flat fee for all services indicates a fixed cost structure, which differs from coinsurance’s percentage-based model. Full coverage implies that the insurance pays 100% of the costs, not requiring any payment from the insured, which contradicts the principle of coinsurance. Finally, a complete waiver of out-of-pocket costs suggests that there would be no financial responsibility on the part of the insured, which stands in direct contrast to the essence of coinsurance, where the insured must contribute a percentage of the costs.