Which statement best describes 'co-insurance' in health plans?

Co-insurance refers to the percentage of health care costs that the insured is responsible for paying after they have met their deductible. This means that once the insured has paid their deductible, which is a specified amount of money they must pay out-of-pocket before their insurance begins to cover costs, they will then share the costs of medical services with their insurance company.

For example, if a health plan has an 80/20 co-insurance structure, the insurance company would cover 80% of covered medical expenses after the deductible is met, while the insured would be responsible for the remaining 20%. This system is designed to encourage cost-sharing between the insurer and the insured, ultimately promoting responsible usage of healthcare services.

The other options describe different aspects of health insurance and do not accurately define co-insurance. The total amount paid for premiums in a lifetime pertains to the overall cost of maintaining coverage, while the fixed amount paid for every medical service refers to co-pays, and the total out-of-pocket maximum relates to a cap on the total costs the insured could potentially pay in a given year.