Medicare Enrollment
Medicare Enrollment Periods — Know Your Windows
Medicare has six distinct enrollment windows. Missing the wrong one can mean a permanent penalty added to your premium — or a one-time guaranteed-acceptance window that never reopens. Here's exactly when each period runs and what you can do during it.
Initial Enrollment Period
7 months centered on your 65th birthday
Opens 3 months before your birthday month, includes it, closes 3 months after. This is your first chance to enroll in Parts A, B, and D.
Annual Enrollment Period
October 15 – December 7
The broadest window — anyone on Medicare can switch MA plans, switch Part D plans, join or drop MA, or return to Original Medicare. Changes take effect January 1.
MA Open Enrollment Period
January 1 – March 31
One switch only — and only if you're already in a Medicare Advantage plan. You can move to a different MA plan or drop MA and return to Original Medicare.
Special Enrollment Periods
Triggered by a qualifying life event
Moving, losing employer coverage, qualifying for Medicaid, your plan losing its CMS contract — these and other events open a time-limited window to make changes.
General Enrollment Period
January 1 – March 31
Enroll in Part B or premium-Part A January 1 through March 31 if you need the GEP. Coverage starts the month after you sign up. A late enrollment penalty may apply; first check whether you qualify for a Special Enrollment Period.
Medigap Open Enrollment
6 months from when you're 65+ AND enrolled in Part B
The only time you're guaranteed acceptance into any Medigap plan at standard rates — no medical underwriting. This window does not repeat. Missing it can mean permanent higher premiums or denial.
The enrollment that affects you most at 65: IEP + Medigap
Two windows are especially critical when you first enter Medicare:
Initial Enrollment Period (IEP)
Your IEP is a 7-month window — 3 months before your birthday month, your birthday month, and 3 months after. Enroll during the 3 months before your birthday month for the earliest coverage start. Waiting until your birthday month or later shifts your start date to the first of the next month for Part B and premium-Part A. Premium-free Part A follows different rules; a birthday on the first of the month shifts age-65 timing to the preceding month.
Group health coverage based on current employment may qualify you for a Part B SEP. Confirm which insurer pays first before delaying, especially with fewer than 20 employees. The window generally ends 8 months after employment or that coverage ends, whichever happens first. COBRA and retiree coverage do not extend it. Part D drug creditability is a separate determination.
Medigap Open Enrollment — the one-time window
If you plan to use Original Medicare (rather than Medicare Advantage), the 6-month Medigap open enrollment window is the most important of all. It opens when you are 65 or older AND enrolled in Part B. During this window, every Medigap insurer in North Carolina must accept your application at standard rates — your health history is irrelevant.
Once the window closes, insurers can require full medical underwriting. Some conditions (recent cancer, certain heart issues, COPD) can result in denial. This is not a renewable window — it happens once.
The Annual Enrollment Period (AEP) — your yearly review window
October 15 – December 7. Every year. This is the one window when every Medicare beneficiary can make any plan change: switch Medicare Advantage plans, switch Part D plans, join or drop Medicare Advantage, or return to Original Medicare.
Changes take effect January 1. If you make multiple elections before December 7, the last one wins — you can change your mind right up until the deadline.
You should review your plan every AEP even if you don't switch. Your Annual Notice of Change (ANOC) arrives by September 30 and lists every change to your plan for the coming year — premium increases, formulary tier changes, network changes. A drug that moves from Tier 2 to Tier 4 can cost hundreds more per year even if your premium stays flat.
All enrollment periods at a glance
| Period | Dates | Who it's for | What you can do | Effective date |
|---|---|---|---|---|
| IEP | 3 mo before birthday thru 3 mo after | Turning 65 / newly eligible | Enroll in A, B, D; join MA | Depends on when within window |
| GEP | Jan 1 – Mar 31 (annual) | Need enrollment outside IEP/SEP | Enroll in Part B or premium-Part A; penalty may apply | Month after enrollment |
| AEP | Oct 15 – Dec 7 (annual) | Everyone on Medicare | Switch/join/drop MA or Part D; return to Original Medicare | Jan 1 (next year) |
| OEP | Jan 1 – Mar 31 (annual) | Currently in a MA plan only | One MA-to-MA switch or drop to Original Medicare | First of following month |
| SEP | Varies by event | Those with qualifying life event | Switch or enroll based on event type | Varies |
| Medigap OE | 6 months from Part B start at 65+ | New to Part B at 65 or older | Any Medigap plan — guaranteed issue | Plan start date |
Late enrollment penalties — check the exceptions
Part B Penalty
+10% per full 12-month period of delay without a qualifying exception. Generally added while you have Part B; qualifying SEPs and Medicare Savings Programs may prevent a penalty.
Part D Penalty
1% per full uncovered month, calculated on the national base beneficiary premium, after a gap of 63 or more days following your IEP. Generally continues while you have drug coverage; Extra Help recipients do not pay this penalty.
Creditable employer coverage, VA drug benefits, and TRICARE can satisfy the Part D requirement and let you delay enrollment without penalty. Always get written confirmation of creditable status from your plan each year.
Enrollment period questions
When does the Annual Enrollment Period start and end?
The Annual Enrollment Period (AEP) runs October 15 through December 7 every year. It's the one window when every Medicare beneficiary can freely change plans. Changes made during AEP take effect January 1 of the following year.
Can I delay Medicare at 65 if I'm still working?
Group health coverage based on your or your spouse's current employment may qualify you for a Part B Special Enrollment Period. Confirm payment order before delaying, especially with fewer than 20 employees. The window generally ends 8 months after employment or that coverage ends, whichever happens first. COBRA and retiree coverage do not extend it. Part D separately requires creditable prescription drug coverage.
What is the Medigap open enrollment period and why does it matter?
It's a 6-month window that opens when you are 65 or older and first enroll in Part B. During this window, no insurance company can deny you a Medigap plan or charge you more because of your health history — that's called guaranteed issue. Once the window closes, NC insurers can use medical underwriting, which can mean higher premiums or outright denial if you have certain conditions.
What is a Medicare Special Enrollment Period?
A Special Enrollment Period (SEP) lets you make changes to your Medicare coverage outside of AEP when a qualifying event happens — moving to a new service area, losing employer coverage, qualifying for Medicaid, or your plan losing its CMS contract, among others. SEP windows can be short, so act promptly when a qualifying event occurs.
What happens if I miss my enrollment window?
Part B may charge 10% of the standard premium for each full 12-month period of delay without a qualifying exception. Part D may charge 1% of the national base beneficiary premium per full uncovered month after a gap of 63 or more days following your Initial Enrollment Period. These generally continue while you have that coverage, but exceptions apply, including Extra Help for Part D. Check for a Special Enrollment Period before waiting for the GEP.
Related Medicare resources
- Medicare FAQ →
Answers to the most common enrollment questions.
- Medicare 101 →
Parts A, B, C, and D explained in plain English.
- Medigap plans →
Medicare Supplement options by location.
- Medicare by county →
Local plan counts and coverage data for your area.
For the most current enrollment deadlines, visit Medicare.gov — Joining a Plan.
Not sure which window applies to you?
Every situation is different. A free 30-minute call with a licensed agent clarifies exactly which window you're in and what your options are — before a deadline passes.
Talk to Kayla Price — it's free →Informational purposes only. Medicare enrollment rules, premium amounts, and plan availability change annually and vary by individual circumstances. Always confirm enrollment deadlines at Medicare.gov or by calling 1-800-MEDICARE (1-800-633-4227). We do not offer every plan available in your area. Please contact Medicare.gov or 1-800-MEDICARE to get information on all of your options. Not affiliated with or endorsed by the U.S. government or the federal Medicare program. NPN: 18530055. Agency NPN: 20387435.