Medicare · Enrollment Periods
Medicare Annual Enrollment Period (AEP)
Key takeaways
- AEP is October 15 – December 7 every year — the primary window to change Medicare Advantage and Part D plans
- Changes take effect January 1 of the following year
- Even if you like your plan, plans change every year — formularies, networks, premiums, and cost-sharing are all updated annually
- AEP applies to Medicare Advantage and Part D plans, not Wisconsin Medigap supplement policies
- A 15-minute annual review can save hundreds of dollars — we do it free for every client every fall
What is the Annual Enrollment Period?
The Medicare Annual Enrollment Period (AEP) — also called the Fall Open Enrollment Period — is the yearly window when Medicare beneficiaries can change their Medicare Advantage plans or Part D prescription drug plans. It runs October 15 through December 7 every year, and any changes made take effect January 1 of the following year.
AEP exists because Medicare Advantage and Part D plans can change significantly from year to year — premiums, drug formularies, provider networks, copays, and out-of-pocket maximums all update annually. Without an annual review, you may find yourself in a plan that no longer fits your needs or has become significantly more expensive.
What AEP is — and what it isn't
AEP covers
- Switching from Original Medicare to Medicare Advantage
- Switching from Medicare Advantage to Original Medicare
- Switching from one Medicare Advantage plan to another
- Enrolling in a Part D prescription drug plan
- Dropping a Part D plan (if you're enrolling in Advantage with drug coverage)
- Switching from one Part D plan to a different Part D plan
AEP does NOT cover
- Enrolling in Medicare Part A or Part B (that's the Initial Enrollment Period or General Enrollment Period)
- Changing a Wisconsin Medigap supplement policy (no special AEP window for Medigap)
- Guaranteed-issue access to Wisconsin Medigap if switching from Advantage — you typically need health underwriting
- Making more than one change that conflicts (e.g., you can't enroll in two Advantage plans)
Why you should review your plan every fall
Many people assume that if their plan worked well last year, they can simply let it roll over. This is one of the most expensive passive decisions in Medicare.
Your drug formulary may have changed
Part D plans update their formularies every January 1. A medication you paid $15/month for may move to a higher tier at $75/month — or be dropped from coverage entirely. Your plan should send you an Annual Notice of Change (ANOC) by September 30. Review it carefully, and have us run your drug list against every available plan.
Your doctor may no longer be in-network
Medicare Advantage provider networks change annually. Gundersen Health System and Mayo Clinic Health System both negotiate contracts with Advantage carriers — and participation can change year over year. The plan that included your cardiologist last year may not include them next year.
Premiums and cost-sharing are updated
A $0-premium Advantage plan can increase its specialist copay from $40 to $60 — or raise its out-of-pocket maximum. These changes accumulate. Reviewing every fall catches increases before they affect your budget.
Better options may now exist
New plans enter markets, existing plans improve their benefits, and carriers compete for your enrollment. A plan that didn't exist in your county last year might now be the best option for your situation. We compare every plan available in La Crosse County and Winona County every fall.
Your health situation may have changed
A new diagnosis, a new prescription, a new specialist relationship — any of these can shift which plan is best for you. The plan optimized for your needs at 67 may not be optimal at 72. Annual reviews catch these shifts before they cost you money.
How to review your Medicare plan during AEP: step by step
Read your Annual Notice of Change (ANOC)
Your current plan must send you an ANOC by September 30 each year. It details every change to your plan for the coming year: premium, copays, formulary updates, network changes, and benefits. If you didn't receive it, call your plan or check online. Read it before October 15.
Gather your current doctor and prescription lists
Write down every provider you saw in the past year — primary care, specialists, hospitals. List every prescription drug with its dosage and frequency. This is the input we need to compare your options accurately.
Compare all plans in your county
In La Crosse County and Winona County, there are typically 15–25 Medicare Advantage plans and 20+ Part D plans available each year. We compare every one against your provider list, drug list, and the specific cost-sharing details that affect your actual spending — not just the premium.
Verify network and formulary for your top choices
For Advantage plans: confirm every provider you use is in the plan's network for the new year (networks change). For Part D: confirm your drugs are on the formulary at their current tier. Don't rely on last year's information.
Enroll in your chosen plan before December 7
Make your change through your new plan directly, through Medicare.gov, by calling 1-800-MEDICARE, or through a licensed local agent. Enrollment confirmation should arrive before January 1. Keep your old plan card until January 1 when new coverage takes effect.
All Medicare enrollment periods at a glance
AEP is the main annual window, but it's not the only one. Here's the full calendar:
| Period | When | Who it's for | What you can do |
|---|---|---|---|
| Annual Enrollment Period (AEP) | Oct 15 – Dec 7 | All Medicare beneficiaries | Switch Advantage or Part D plans; enroll in or drop plans. Changes effective Jan 1. |
| MA Open Enrollment Period (MA OEP) | Jan 1 – Mar 31 | People already in Medicare Advantage | Switch to a different Advantage plan or return to Original Medicare. One change only. |
| Initial Enrollment Period (IEP) | 7 months around 65th birthday | People turning 65 (or newly eligible) | Enroll in Parts A, B, C, and D for the first time. |
| Special Enrollment Periods (SEPs) | Triggered by qualifying events | People with qualifying life events | Enroll or change plans after losing coverage, moving, plan termination, and other events. |
| General Enrollment Period (GEP) | Jan 1 – Mar 31 | People who missed their IEP | Late enrollment in Part B (with potential penalty). Coverage starts July 1. |
| Medigap Open Enrollment (WI) | 6 months from Part B effective date | People newly enrolling in Part B at 65 | Guaranteed-issue Wisconsin Medigap enrollment. Underwriting required after this window. |
Wisconsin Medigap and AEP: an important distinction
One of the most common misconceptions among Wisconsin Medicare beneficiaries: AEP does not apply to Wisconsin Medicare Supplement (Medigap) policies.
Wisconsin Medigap policies are not enrolled or changed through the AEP window. They are purchased directly from carriers and are subject to different rules:
- Your guaranteed-issue window for Wisconsin Medigap is a one-time 6-month period starting when you first enroll in Part B at 65
- Outside that window, switching Medigap carriers or adding riders typically requires health underwriting
- If you're currently on Medicare Advantage and want to switch to Original Medicare + Medigap during AEP, you can change to Original Medicare — but getting a Medigap policy may require passing health underwriting unless you qualify for a guaranteed-issue special situation
If you're currently on Medicare Advantage and considering a move to Wisconsin Medigap, talk to us before AEP to understand your underwriting exposure. Waiting until you have a health event makes this transition significantly harder.
AEP frequently asked questions
When is the Medicare Annual Enrollment Period?
The Annual Enrollment Period (AEP) runs October 15 through December 7 every year. Changes you make during AEP take effect January 1 of the following year. This is the main window for Medicare Advantage and Part D plan changes.
What can I change during AEP?
During AEP you can: switch from Original Medicare to Medicare Advantage; switch from Medicare Advantage back to Original Medicare; switch from one Medicare Advantage plan to another; enroll in, drop, or switch standalone Part D drug plans. Changes take effect January 1.
Can I switch from Medicare Advantage to a Wisconsin Medigap policy during AEP?
Switching from Medicare Advantage to Original Medicare during AEP is possible — but enrolling in a Wisconsin Medicare Supplement (Medigap) after AEP typically requires health underwriting unless you have a guaranteed-issue right. Simply switching from Advantage to Original Medicare during AEP does not give you guaranteed acceptance for Medigap. You may need to pass underwriting to add Medigap. We review whether you qualify for any special guaranteed-issue protections.
What happens if I don't make any changes during AEP?
Your current plan automatically renews for the following year with any changes the plan has made to its premiums, formulary, network, or cost-sharing. This is why reviewing your plan every fall matters — the plan you enrolled in last year may have changed significantly.
My Part D plan changed its formulary. What can I do during AEP?
Formulary changes are one of the most common reasons to switch Part D plans during AEP. If your medications were moved to a higher tier, dropped from the formulary, or the plan added a large deductible, switching to a plan with better coverage for your drugs can save hundreds of dollars annually. We run your current prescription list against every plan available in your county each fall.
Is there a different enrollment period for Medicare Advantage in early winter?
Yes. The Medicare Advantage Open Enrollment Period (MA OEP) runs January 1 through March 31. During this window, people already enrolled in a Medicare Advantage plan can switch to a different Advantage plan or return to Original Medicare (and enroll in Part D). You can only make one change during the MA OEP.
I'm happy with my current plan. Do I still need to review it?
Yes — even if you're satisfied, plans change every year. Your Advantage plan might raise a specialist copay, drop a doctor from its network, change its drug formulary, or increase your maximum out-of-pocket. A 15-minute annual review confirms your plan is still your best option or identifies a better one. We do this review for every client every fall at no cost.
Does AEP apply to Wisconsin Medicare Supplement (Medigap) policies?
No. AEP applies to Medicare Advantage and Part D plans. Wisconsin Medicare Supplement policies are not purchased through AEP — they are purchased directly from carriers. Switching Medigap policies outside your guaranteed-acceptance window requires health underwriting regardless of AEP timing.
Every fall · Free · No pressure
We review your plan every AEP — for every client
Don't let your Medicare plan auto-renew without a review. We compare every plan in La Crosse County and Winona County against your providers, prescriptions, and budget each fall. Takes about 15 minutes. Has saved clients hundreds.
Schedule your AEP review → (608) 799-8434Related: All Medicare enrollment periods · Turning 65 checklist · Annual coverage review service
We do not offer every plan available in your area. Any information we provide is limited to those plans we do offer in your area. Please contact Medicare.gov, 1-800-MEDICARE, or your local State Health Insurance Assistance Program (SHIP) to get information on all of your options. Not affiliated with or endorsed by the U.S. government or the federal Medicare program. This page is for general information only — not medical, insurance, tax, or legal advice. Hougom Insurance Agency is a licensed independent insurance agency (NPN 20742808).