If you are newly eligible for Medicare, you can enroll three months prior to the month you become eligible and up to three months after the month you become eligible — a seven-month period.
You can also join every year during open enrollment, which is October 15 through December 7. Otherwise, you can join outside of open enrollment without a penalty if:
1. You were to lose “creditable” drug coverage (coverage as least as good as Medicare’s) from your employer or union;
2. You qualify for the Extra Help program in paying for Part D.