The Prescription Drug Plan (Medicare Part D) helps to cover the cost of your prescriptions. It is often included with Medicare Advantage (Part C) plans. Stand-alone Part D plans, to accompany an Original Medicare plan, are available.
Not everyone needs a Part D prescription drug plan. However, if you decide not to enroll in Part D, there is a penalty per month from the time you first enroll in Medicare Part B until you finally enroll in a Part D plan, which will apply to your premiums as long as you have coverage. That amount can change each year.