Medicare Enrollment Periods — When and How to Sign Up

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 extends 3 months after. This is the best time to enroll in Medicare Part A and Part B. If you miss your IEP without qualifying for a Special Enrollment Period, you may face a late enrollment penalty.

• 3 months before your 65th birthday month
• Your birthday month
• 3 months after your birthday month
• Total window: 7 months

Special Enrollment Period (SEP)

If you are still working at 65 and covered by employer health insurance, you can delay Medicare without penalty. When you retire or lose that employer coverage, you qualify for an 8-month Special Enrollment Period to sign up for Medicare Part B. It is important to act within this window to avoid a late enrollment penalty.

• Available when you lose employer coverage
• 8-month window to enroll in Part B
• No late enrollment penalty if you enroll in time
• Also available for other qualifying life events

General Enrollment Period (GEP)

If you missed your Initial Enrollment Period and do not qualify for a Special Enrollment Period, you can sign up during the General Enrollment Period, which runs from January 1 through March 31 each year. Coverage begins July 1. You may face a late enrollment penalty that increases your Part B premium permanently.

Annual Enrollment Period (AEP)

The Annual Enrollment Period runs from October 15 through December 7 each year. During this window, you can switch between Original Medicare and Medicare Advantage, change your Medicare Advantage plan, or change your Part D prescription drug plan. Changes take effect January 1 of the following year.

Medicare Advantage Open Enrollment Period

From January 1 through March 31, people already enrolled in a Medicare Advantage plan can switch to a different Medicare Advantage plan or return to Original Medicare (and add a Part D plan). This period is separate from the Annual Enrollment Period.

Avoiding Late Enrollment Penalties

The Part B late enrollment penalty adds 10% to your monthly premium for each full 12-month period you were eligible but did not enroll. This penalty is permanent and lasts for as long as you have Medicare. The Part D late enrollment penalty is calculated differently but is also permanent. Working with a licensed agent like AG Insurance helps you navigate enrollment windows and avoid costly mistakes.