When to Enroll in Medicare

Initial Enrollment Period (IEP)

Your Initial Enrollment Period is a 7-month window that begins 3 months before the month you turn 65, includes your birthday month, and ends 3 months after. Enrolling during the first 3 months of your IEP ensures your coverage starts on the first day of your birthday month. Enrolling in months 4–7 delays your start date by 1–3 months.

Special Enrollment Period (SEP)

If you or your spouse are still working and covered by an employer group health plan when you turn 65, you can delay Medicare enrollment without penalty. You have an 8-month Special Enrollment Period to sign up for Part A and Part B after your employment or employer coverage ends — whichever comes first. COBRA and retiree health coverage do not qualify as current employer coverage for SEP purposes.

General Enrollment Period (GEP)

If you miss your IEP and do not qualify for an SEP, you can enroll during the General Enrollment Period from January 1 to March 31 each year, with coverage starting July 1. However, you will pay a late enrollment penalty on your Part B premium for as long as you have Medicare.

Part B late enrollment penalty

The Part B late enrollment penalty is 10% of the standard Part B premium for each full 12-month period you were eligible but did not enroll. This penalty is permanent and is added to your Part B premium for life. At the 2025 standard premium of $185/month, each year of delay adds $18.50/month permanently.