Co-insurance is an amount a covered person pays toward medical care that is protected by health insurance. Someone with an 80-20 co-insurance setup pays 20 percent of the remaining post-deductible balance on qualified treatment.
If a total service bill is $10,000 and the insured has a $500 deductible and a 20 percent co-insurance, the total patient obligation is $2,400, which is the $500 plus a $1,900 co-insurance. Common patient co-insurance percentages range from zero to 40. A zero percent co-insurance means the patient has no payment obligations on covered treatment beyond the required deductible payment. Insurers often have annual patient maximums on co-insurance payments.