pharmacy benefit effective coinsurnace help

Let's say the benefit design goes like "maximum of 20% coinsurnace or $250" for the specialty drug. I need to convert this into a an effective coinsurnace. Assume the allowed amount used to calculate coinsurance is $1500.



For example, if the copay is 250, effective coinsurance is 1-250/1500= 83%.



Can anyone tell me how to model "maximum of 20% coinsurnace or $250" before I yell at the benefit design person? Thanks.

pharmacy benefit effective coinsurnace help