When you first sign up for Medicare, the focus is often on getting Parts A and B in place. But once you’re enrolled, the real work begins—especially if your needs change over time. Medicare also comes with a lot of confusing jargon, deadlines, and enrollment periods, which makes it easy to get overwhelmed. That’s why knowing when you can update your coverage is just as important as knowing how to enroll in the first place.
Two of the most critical Medicare enrollment windows happen each year—but they serve very different purposes. If you’re not clear on the difference, you could miss your chance to improve your plan or end up stuck with coverage that no longer fits.
Let’s break down the two big enrollment periods: Annual Open Enrollment (AEP) and Medicare Advantage Open Enrollment (MA-OEP).
Annual Open Enrollment (October 15 – December 7)
This is the big one. From mid-October through early December each year, all Medicare beneficiaries can make changes to their coverage. This window is especially important if:
- You’re thinking about switching between Medicare Advantage and Original Medicare
- You want to enroll in a new Part D prescription drug plan
- Your current plan is changing its network or drug formulary
- You’re looking for better coverage or more predictable out-of-pocket costs
Any changes you make during this period take effect on January 1 of the following year.
If you’re unsure whether your current plan still fits—this is the time to review your coverage, compare options, and make a move if needed. Waiting until January means you’ll have to stick with your current plan for a while longer.
Medicare Advantage Open Enrollment (January 1 – March 31)
This second window is often confused with AEP—but it’s only for people who are already enrolled in a Medicare Advantage (Part C) plan.
Here’s what you can do during this time:
- Switch to a different Medicare Advantage plan
- Drop Medicare Advantage entirely and go back to Original Medicare
- Enroll in a standalone Part D drug plan (if you return to Original Medicare)
You can’t use this window to switch from Original Medicare to Medicare Advantage, or to add a Part D plan if you’re not leaving an Advantage plan.
So if you joined a Medicare Advantage plan during the fall and realize it’s not what you expected—maybe your doctor isn’t in-network or your prescription coverage is lacking—this is your chance to change course.
Why These Windows Matter
These enrollment periods are separate from your Initial Enrollment Period (IEP)—the 7-month window tied to your 65th birthday. Once that window has passed and you’re on Medicare, the Annual Enrollment Period and the Advantage OEP become your main opportunities to reassess and adjust.
If your health changes, your prescriptions shift, or your provider network shrinks, missing these dates can leave you locked into a plan that’s no longer right for you.
Need Help Choosing the Right Plan? That’s What We’re Here For.
Navigating Medicare can feel complicated, but these enrollment windows aren’t just dates on a calendar—they’re moments where you can take control of your coverage. If your health needs have changed, your medications have gotten more expensive, or your current plan simply isn’t working like it used to, these windows give you a chance to do something about it. The reality is, many people don’t realize their plan is no longer a good fit until it’s too late to make a change. That’s why it’s worth taking the time now to review your options, ask questions, and make sure your coverage still matches your needs.
You’ve worked hard to earn your Medicare benefits—now it’s time to make sure they’re working for you. If you want help understanding your choices or getting a second opinion, you can call (800) 864‑8890 or book a free consultation with a licensed Medicare expert. It’s a small step that could make a big difference in your peace of mind and your pocketbook.