When does my Medicare coverage start?

If you sign up around your 65th birthday

Your Initial Enrollment Period is seven months long: the three months before your birthday month, the birthday month itself, and the three months after. When coverage begins depends on which part of that window you use:

• Sign up in the three months before your birthday month — coverage starts the first day of your birthday month.
• Sign up during or after your birthday month — coverage starts the first day of the following month.

If you sign up after employer coverage ends

If you delayed Medicare because you had active job-based coverage, you use a Special Enrollment Period. Coverage generally begins the first of the month after you enroll, though you can usually choose to start it sooner.

If you missed your window

If you didn’t enroll when first eligible and don’t have a Special Enrollment Period, you sign up during the General Enrollment Period, January 1 to March 31. Under the current rules your coverage starts the first of the month after you enroll — but you may owe a permanent late-enrollment penalty.