Glossary
IEP (Initial Enrollment Period)
The seven-month window around your 65th birthday when you first sign up for Medicare.
IEP stands for Initial Enrollment Period. It is your first chance to sign up for Medicare, and it lasts seven months: the three months before the month you turn 65, the month itself, and the three months after. The month you act inside that window decides when coverage begins, and coverage always starts on the first of a month. Signing up in the earlier part of the window is what lets coverage begin the month you turn 65 rather than later. This matters to you because missing the window has lasting consequences rather than temporary ones. Without other qualifying coverage, a late start can bring a permanent addition to your Part B premium and a wait before coverage begins. If you are already receiving Social Security before 65, you are usually enrolled in Parts A and B automatically and your card arrives in the mail, so the window passes without you needing to do anything.