Medicare Enrollment Periods: IEP, AEP, OEP, and SEPs

Initial Enrollment Period (IEP)

Your first chance to sign up for Medicare. It starts three months before the month you turn 65, includes your birthday month, and ends three months after, for seven months total. If your birthday is on the first of the month, the whole window shifts one month earlier.

During your IEP you can enroll in Part A and Part B, join a Medicare Advantage plan, and join a Part D drug plan. When your coverage starts depends on when you sign up: enroll in the three months before your birthday month and coverage begins the first day of that month. Enroll during your birthday month or the three months after and coverage begins the first day of the month after you sign up.

General Enrollment Period (GEP)

If you miss your IEP and do not qualify for a Special Enrollment Period, you can sign up for Part A and Part B between January 1 and March 31 each year. Coverage starts the first of the month after you enroll. A late enrollment penalty may apply, and it may be permanent.

Annual Election Period (AEP)

Every year from October 15 to December 7, anyone with Medicare can join, switch, or drop a Medicare Advantage plan or Part D drug plan. Changes take effect January 1.

This is the window most people use to review their coverage. Plans change their premiums, formularies, networks, and benefits every year, and your plan mails an Annual Notice of Change each fall describing what is different. Even if you are happy, a yearly review is worth the half hour.

Medicare Advantage Open Enrollment Period (MA OEP)

From January 1 to March 31, if you are already in a Medicare Advantage plan, you can make one change: switch to a different Advantage plan, or return to Original Medicare and add a Part D plan. You cannot use this window to move from Original Medicare into an Advantage plan, and you cannot switch standalone Part D plans alone.

Special Enrollment Periods (SEPs)

Certain life events let you enroll or change plans outside the normal windows. Common ones include:

• Losing employer or union coverage. After active employer coverage ends, you have an 8-month window to enroll in Part B without penalty, and a shorter window to join a Part D or Advantage plan.
• Moving out of your plan's service area, or moving somewhere with new plan options.
• Qualifying for Medicaid or Extra Help with prescription costs.
• Your plan leaving Medicare or ending its contract.
• Moving into or out of a skilled nursing facility or other institution.
• Switching to a plan with a 5-star Medicare rating, which has its own once-a-year window.

Still working at 65?

If you or your spouse are actively working and you have coverage through that employer, you may be able to delay Part B without penalty, especially if the employer has 20 or more employees. COBRA and retiree coverage do not count as active employer coverage for this purpose. Rules differ for smaller employers, so confirm with your benefits administrator and Social Security before deciding to delay.

The penalties for missing a window

If you are not sure which window applies to you, call us. Sorting out enrollment timing is one of the most common things we help with, and it costs nothing.

• Part B: your premium rises 10 percent for each full 12-month period you could have had Part B but did not, for as long as you have Part B.
• Part D: if you go 63 days or more without creditable drug coverage after you are first eligible, a penalty based on the number of months without coverage is added to your premium, usually permanently.