Coinsurance is when you and your insurance company share the cost of healthcare services after you’ve met your deductible and until you reach your out of pocket maximum. For instance, with, say, 50% coinsurance, you would pay half of your medical costs and your insurance would cover the other half until you reach your out-of-pocket maximum. So, if you were to have a $1000 surgery, you would pay $500, and your insurance would pay the remaining $500.