Medicare Part D helps pay for costs related to prescription medications. It is a standalone private plan. You may sign up for coverage when you enroll in Part A and/or Part B. You will not be able to qualify for a Part D plan without coverage from either Part A, Part B or both.

If you do not sign up when you are first possible and do not have other drug coverage, you will need to pay a lifetime penalty each month when you do enroll. 

Your Part D premium will depend on your tax return from two years ago. Premiums can range from $0 to $77.10 (+ your plan premium) for just drug coverage. You will also need to meet your annual deductible before your plan begins to help cover medication costs. 

While Part D plans round-out coverage with Original Medicare, they are from private providers like Part C. This means you must select a plan that fits your service area. You cannot sign up for a drug plan that does not match your zip code. 

Since Part D drug plans are regionally based, you will be disqualified from coverage if you move out of the service area.

Fortunately, your move to a new state or area makes you able to switch or change your plan. 

Each Part D is unique, so you should check to verify that your potential plan covers your prescriptions. For instance, your plan may only pay for generic drugs, not brand name medications. 

There may also be restrictions on your policy, such as requiring prior authorization to cover the drug.

Each plan sets different conditions, so you should compare different options to find the one that fits your needs best. But those are not all the requirements to sign up for a Medicare health insurance plan. See if you meet the other requirements to enroll.