When is the deadline? What happens if you miss it? 

You can join a Medicare drug plan from three months before you turn 65 to three months after you turn 65. Generally, if you are disabled, you can join three months before and three months after your 25th month of disability.

If you miss these deadlines you may face a penalty in the first year of the plan.

Nov 15 – December 31: The next penalty-free period for switching plans. New coverage takes effect Jan. 1.