When Is Medicare Open Enrollment? The main annual window (often called the Annual Enrollment Period, or AEP) runs from October 15 to December 7. During this period, you can review your current coverage and make changes that begin on January 1. Even if you like your plan, it is still smart to review it each year. Premiums can change, copays can shift, networks can update, and prescription drug formularies can move medications into different tiers. Small changes can create big cost differences over a 12-month period.

At Diversified Insurance Brokers, our role during AEP is to help you avoid surprises. We compare plans side by side, focusing on what matters most: keeping your doctors, covering your medications, and balancing premium cost against out-of-pocket exposure. If you have ever renewed automatically and then discovered your specialist is no longer in network—or your prescription is suddenly much more expensive—you already understand why an annual review matters. If you are still learning the process, this is a good place to start: Medicare enrollment mistakes to avoid.

What You Can Change Between October 15 and December 7

During AEP, Medicare beneficiaries can make several important changes. The best way to think about it is this: you are allowed to adjust how you receive Medicare services and how you cover prescription drugs. The exact options you have depend on whether you are currently on Original Medicare (Parts A and B) or enrolled in a Medicare Advantage plan (Part C). In either case, AEP is the primary time each year when you can reposition your coverage to reduce costs or improve access.

Switch to Medicare Advantage (Part C) if you are currently on Original Medicare and want a plan that bundles coverage with copays, an annual out-of-pocket maximum, and often additional benefits such as dental or vision. Medicare Advantage can be attractive for people who want lower premiums and are comfortable using provider networks. If you want the basics and key trade-offs, start here: Medicare Part C explained.

Return to Original Medicare if you are currently on a Medicare Advantage plan and you want broader provider flexibility. Many people consider switching back when they travel frequently, want fewer network restrictions, or prefer a more predictable cost structure with a Medicare Supplement plan. If you are comparing structures, this side-by-side guide is helpful: Medicare Advantage vs. Medicare Supplement comparison.

Change your Part D prescription drug plan to improve drug coverage, reduce premium, or better align with your preferred pharmacy. This is one of the most common AEP changes because formularies and tier structures change frequently. If you want a quick foundation, see Medicare Part D explained. The most important AEP tip is this: do not assume “my plan covered it last year, so it will cover it the same way next year.” That is not how Part D works in practice.

Review Medicare Supplement (Medigap) options if you are on Original Medicare and want help reducing cost sharing. Many people look at Medigap when they want fewer surprises from deductibles and coinsurance. The most common comparison we run for clients is Medicare Supplement Plan G vs. Plan N, because the decision often comes down to premium level versus paying small copays for certain visits.

Key Dates and Related Enrollment Windows

Medicare has multiple enrollment windows, and confusing them is one of the fastest ways to miss an opportunity—or assume you can make a change that is not available. AEP is the main annual “reset” window for coverage changes, but other windows exist depending on your situation.

Annual Enrollment Period (AEP): Oct 15 – Dec 7. Changes generally begin Jan 1. This is when most people switch plans, change Part D coverage, or move between Original Medicare and Medicare Advantage.

Medicare Advantage Open Enrollment (MA OEP): Jan 1 – Mar 31. This is only for people who are already enrolled in a Medicare Advantage plan on January 1. During this window, you can switch to another Medicare Advantage plan or return to Original Medicare and add Part D. This window is often used to fix a plan choice that looked good during AEP but feels wrong once the plan year begins.

Special Enrollment Periods (SEPs): These occur when specific life events happen, such as moving, losing employer coverage, changes in Medicaid eligibility, or other qualifying circumstances. If you are still working at or after 65, the timing rules become especially important. If that’s you, this guide helps clarify the steps: How to get Medicare while working.

Smart Prep Checklist: What to Gather Before You Compare

Open Enrollment decisions are much easier when you have the right information ready. The goal is to compare plans using your actual doctors, medications, and pharmacy—not generic assumptions. If you want your results to be accurate, start with these items before comparing:

Prescriptions: Write down the exact drug name, dosage, and how often you take it. Include any specialty medications, inhalers, injectables, or “as needed” prescriptions that you refill regularly. This matters because Part D pricing and tier placement can shift year to year.

Preferred pharmacies: If you have a pharmacy you like, include it. Some plans offer significantly lower pricing at preferred pharmacies. If you travel often, note if you need national pharmacy access.

Doctors and hospitals you want to keep: Provider networks are one of the biggest differences between Medicare Advantage plans. If keeping a specific specialist is important, that must be checked carefully.

Expected care next year: Planned procedures, therapies, specialist follow-ups, and ongoing management of chronic conditions can change which plan is best. A plan that looks “cheap” for a healthy year may be expensive when usage increases.

Travel patterns: If you spend time in another state, network limitations can become a problem with Medicare Advantage. This is a common reason people consider Original Medicare plus a Supplement plan.

Budget preferences: Some people prefer a lower premium even if it means higher copays. Others prefer paying more monthly to reduce out-of-pocket variability. Knowing which style fits you helps narrow choices faster.

Medicare Advantage vs. Original Medicare: A Practical Overview

Medicare Advantage (Part C) bundles your hospital and medical coverage and typically includes prescription drug coverage. Many plans include extras like dental or vision, and they usually feature an annual maximum out-of-pocket limit. This can be helpful for budgeting, but plan rules and provider networks apply. If you want a clear breakdown, see Medicare Part C explained.

Original Medicare + Medigap + Part D is the structure many people choose when they want maximum provider flexibility. Original Medicare provides nationwide access to Medicare-accepting providers, Medigap reduces cost sharing, and Part D covers prescriptions. If you are comparing Supplement plan styles, start with Plan G vs. Plan N and use Part D basics to understand how drug coverage is evaluated.

The “best” choice is usually the one that fits your care usage and access needs. That is why annual reviews matter: your health, medications, providers, and local plan availability can all change over time.

Why Annual Reviews Matter Even If You’re Happy

Many people assume that if their plan worked this year, it will work next year. The problem is that Medicare plans change annually. A plan can remain “fine,” but still become more expensive or less convenient due to changes outside your control. A review helps you spot cost increases early and decide whether to stay or switch.

Formularies change: Your prescription may move to a different tier, require prior authorization, or have a different preferred pharmacy pricing structure. This is one of the biggest drivers of unexpected costs.

Networks shift: Doctors and hospitals can enter or leave networks, especially within Medicare Advantage plans. If you have a specialist you rely on, this must be checked each year.

Costs adjust: Premiums, deductibles, copays, and maximum out-of-pocket limits can change. Some plans also change how they structure copays for common services like imaging, urgent care, and specialist visits.

New plans enter the market: New options may provide better value for your prescription profile or access needs. A quick comparison can help confirm whether your current plan is still competitive.

How We Help During Open Enrollment

We are independent and compare multiple carriers. Our open enrollment process is designed to give you clarity, not confusion. Instead of looking at a plan brochure in isolation, we compare the cost and access implications of multiple plans using your actual inputs.

Clients typically want three things from an AEP review: (1) confidence they can keep their doctors, (2) predictable prescription coverage, and (3) a cost structure that matches their retirement budget. That is why we provide a clear summary of your best options and walk you through the trade-offs. If you want broader Medicare education, you can also explore enrolling in Medicare at age 65 and avoid common timing problems discussed in Medicare enrollment mistakes to avoid.

Budgeting for Premiums and Healthcare Costs

Open Enrollment is a good time to connect plan choices to your retirement budget. Many retirees focus on premium savings but overlook how copays and drug costs can change total spending. If you like to model your budget more carefully, it can help to estimate how stable income sources support ongoing healthcare costs.

Avoid These Common Open Enrollment Mistakes

Most “bad Medicare outcomes” during AEP come from a few predictable mistakes. Avoiding these usually saves both money and frustration.

Auto-renewing without review: Even if you keep the same plan, the costs and rules can change. A short review helps confirm it still fits.

Choosing based on premium alone: A low premium can hide higher specialist copays, higher imaging costs, or tighter networks. The goal is total expected spend, not only premium.

Ignoring the drug list: Part D pricing can change dramatically when a medication moves tiers or is no longer preferred at your pharmacy.

Missing deadlines: Most changes must be submitted by Dec 7 to start Jan 1. Waiting until the last week can limit time to verify networks and prescriptions.