Where a co-payment is a fixed amount, co-insurance is a share of the bill. With 20% co-insurance on a S$500 eligible bill, the employee pays S$100 and the insurer pays S$400.
Co-insurance is common on group major medical, where it applies to the amount above the deductible, and on some dental plans. For example, one insurer’s dental plans pay 80% of eligible costs up to the yearly limit.
Like a co-payment, it keeps premiums lower and gives employees a reason to consider the cost of treatment.