What Is Medicare Special Enrollment Period? 
A special enrollment period for original Medicare -LRB- Part A & Part B -RRB- is a qualification to enroll in Medicare immediately without having to wait for the general enrollment period -LRB- January 1-March 31 of each year -RRB- if you did not sign up for Medicare when you were first eligible -LRB- turning age 65 -RRB- - enrolling during a special enrollment period would also allow you to avoid being subject to any late enrollment penalties . With regards to special enrollment periods for Part C -LRB- Medicare Advantage -RRB- and Part D -LRB- stand-alone prescription drug plans -RRB- , it 's a qualification to make changes to your program outside of the annual enrollment period -LRB- October 15-December 7 of each year -RRB- - Medicare supplement plans -LRB- a.k.a. Medigap plans -RRB- can be changed at any time during the year . There are a number of ways someone may qualify for a special enrollment period , the most common one I see being a person leaving their employer 's group health insurance plan . I hope the information is helpful - please feel free to contact me for assistance with your program and if you have any other questions . Thanks very much . 