This is the amount you pay toward the cost of prescription drugs under Part D coverage. This includes coinsurance, copays, deductibles, and payments made while in the coverage gap. It is important to note that your monthly premiums do not count toward your total out-of-pocket costs. They are used by Part D plans to tell the difference between what you pay and the total drug cost, which is the amount paid by you and the plan.
Even though it would ultimately cost him money, the doctor chose to take the accepting assignment amount as full payment.