Important dates to remember OCT 15 TO DEC 7 JAN 1 TO MAR 31 YEAR ROUND Annual Enrollment Period Medicare Advantage Special Enrollment Open Enrollment Period Period Sign up for a Medicare Advantage Make a one-time change to If you qualify, you may plan, with or without prescription another Medicare Advantage plan change plans outside the drug coverage. or Original Medicare. normal enrollment times. Initial Election Period Your first chance to sign up for Medicare Generally, you have 7 months to sign up. The clock starts 3 months before you turn 65, and ends 3 months after that.