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
For people who missed IEP without qualifying coverage. Coverage starts July 1. Late enrollment penalties apply. The GEP is a last resort, not a clean second chance.
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 forward by one to three months.
If you're still working and covered by an employer group health plan at a company with 20+ employees, you can delay Part B without penalty. When that coverage ends, you have an 8-month Special Enrollment Period to enroll. COBRA and retiree coverage do not qualify for the delay exception.
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) | Missed IEP, no qualifying coverage | Enroll in Part B (penalty applies) | July 1 |
| 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 |
Source: CMS Medicare enrollment rules — Medicare.gov
Late enrollment penalties — they're permanent
Part B Penalty
+10% per year you were eligible but didn't enroll (without qualifying employer coverage). Added permanently to your Part B premium. Never goes away.
Part D Penalty
1% per month without creditable drug coverage (after your eligibility date), calculated on the national base beneficiary premium. Also permanent.
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?
Yes — if you have active employer group health coverage through your own job or a working spouse's job at a company with 20 or more employees. When that coverage ends, you have an 8-month Special Enrollment Period to sign up for Part B without a late-enrollment penalty. COBRA and retiree health coverage do not qualify for this delay exception.
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?
Missing Part B enrollment without qualifying employer coverage triggers a permanent 10% premium penalty per year you were late. Missing Part D enrollment triggers a permanent 1%-per-month penalty calculated on the national base beneficiary premium. Both follow you for life.
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 advisor 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.