Co-insurance is what you pay in addition to any deductible you may owe. This is what insurance companies mean when they refer to a 30/70 or 20/80 or 40/60 plan. The first number is the percentage that YOU pay of your healthcare costs once your deductible is reached and until you reach the out-of-pocket maximum. If the allowed amount for a doctor’s office visit in $100 and you’ve met your deductible, you will owe whatever the co-insurance is. Usually it comes in percentages