Just like with Medicare Advantage plans, if you want to enroll in a Part D plan, you must be in an enrollment period or have a valid Special Election Period (SEP).
The first thing you’ll notice about Part D enrollment periods is that they are almost identical to Medicare Advantage (Part C) enrollment periods. In fact, the only real different between the two is that Medicare Advantage has an enrollment window called OEP that runs during January 1 through March 31. This enrollment period is not available for Part D Prescription drug plans.
When you start Medicare Part B, you’ll have an Initial Enrollment Period where you can sign up for a Medicare Advantage plan mid-year.
One of the criteria to be eligible for a Medicare Advantage plan is to live within the plan’s service area. If you move down the street while staying in the service area of your plan, you don’t need to do anything. However, if you’re on a Medicare Advantage plan in Austin, Texas and you decide to move to Miami, Florida, this will put you out of the service area on your existing plan. This gives you an SEP which will allow you to enroll in a Medicare Advantage plan that has coverage in your new location, without you having to wait for one of the main enrollment periods.
If your income & assets are below a certain threshold, you may qualify for the Low-Income Subsidy program that helps cover Part D prescription drug plan premiums and co-pays. Another benefit of being eligible for this is that you also get an SEP to make changes to your Medicare Advantage plan outside of the main enrollment periods. Enrollees with LIS can make one change to their Medicare Advantage plan during each of the first quarters of the year: January-March, April-June, July-September.