Medicare has different enrollment periods throughout the year. The Open Enrollment Period (OEP), also referred to as the Annual Enrollment Period (AEP) is the timeframe in which Medicare benficiaries can change to a different plan. OEP takes place October 15 through December 7. Changes made during the OEP will take affect the following January 1st. You do not have to make a change. If you choose to stay with your current plan you will not need to do anything. However you will receive a new insurance ID card for the upcoming year.
Once the Medicare Open Enrollment period ends on December 7, you will not be able to change to a different plan until the following year. There are some exceptions, such as if you have group insurance or if you move out of the service area of your plan. However, for most people on Medicare the OEP is the only time you can make a change.