You can sign up for Medicare during your Initial Enrollment Period (IEP), starting three months before turning 65, including your birth month, and extending three months after. If you miss your IEP, the General Enrollment Period (GEP) runs from January 1 to March 31 each year. Additionally, there's a Medicare Open Enrollment Period from October 15 to December 7, during which you can make changes to your Medicare coverage for the upcoming year.
