Medicare's Annual Enrollment Period (AEP), running from October 15 through December 7 each year, represents your most important opportunity to review and change your Medicare coverage. During this seven-week window, current Medicare beneficiaries can switch between Original Medicare and Medicare Advantage, change Medicare Advantage plans, add or drop Part D prescription drug coverage, or switch Part D plans. Understanding how to maximize this enrollment period ensures you have the most appropriate, cost-effective coverage for the coming year.

What You Can Change During Annual Enrollment

The Annual Enrollment Period provides maximum flexibility to modify your Medicare coverage. If you have Original Medicare, you can join a Medicare Advantage plan for the first time. If you're in a Medicare Advantage plan, you can switch to a different Medicare Advantage plan, return to Original Medicare (and add a standalone Part D plan if desired), or drop your current Medicare Advantage plan and return to Original Medicare without Part D.

For prescription drug coverage, you can join a Medicare Part D plan if you don't have one, switch from one Part D plan to another, or drop your Part D coverage entirely (though this isn't recommended unless you have other creditable prescription drug coverage, as dropping Part D can trigger late enrollment penalties if you rejoin later).

You can also make combinations of changes. For example, you might switch from Original Medicare with standalone Part D to a Medicare Advantage plan that includes drug coverage, or move from a Medicare Advantage HMO to a Medicare Advantage PPO within the same insurance company or switch to a different company entirely.

Changes you make during the Annual Enrollment Period take effect January 1 of the following year. For instance, if you switch plans during the October 15 - December 7, 2025 enrollment period, your new coverage begins January 1, 2026. This delayed effective date means you should maintain your current coverage through December 31 to avoid gaps.

What you cannot change during the Annual Enrollment Period: You cannot enroll in or change Medigap policies. Medigap has its own enrollment rules tied to your Initial Enrollment Period and certain guaranteed issue situations. The Annual Enrollment Period applies only to Medicare Advantage and Part D plans, not to Medigap supplemental insurance.

Why Annual Plan Review Is Essential

Even if you're satisfied with your current Medicare coverage, reviewing your options every year during the Annual Enrollment Period is crucial. Medicare Advantage and Part D plans change their benefits, costs, formularies, and provider networks annually. What worked perfectly last year might not be your best option this year.

Plan premiums change yearly, sometimes dramatically. Your Medicare Advantage plan might have had a $0 premium last year but could charge $30 monthly this year. Conversely, a plan that charged a premium last year might offer $0 premium coverage this year. Annual review ensures you're not overpaying for similar coverage available elsewhere.

Formularies—the lists of covered prescription drugs—change annually. Your Part D or Medicare Advantage plan might drop one of your medications from its formulary, move it to a higher-cost tier, add new restrictions like prior authorization or step therapy, or change the quantity limits. These formulary changes can significantly increase your out-of-pocket costs if you don't switch to a plan that better covers your current medications.

Provider networks change as well. Your Medicare Advantage plan might drop your longtime primary care physician or preferred hospital from its network, requiring you to change doctors or pay out-of-network costs if you want to continue seeing your preferred providers. Annual review lets you verify all your doctors remain in-network or switch to a plan that includes them.

Your own health situation changes too. New diagnoses, different medications, changed healthcare needs, or recovery from serious conditions all affect which plan provides the best value. A plan optimized for someone with minimal healthcare needs might be expensive and restrictive for someone diagnosed with a chronic condition requiring specialist care and multiple medications.

Plans also change their benefits and extra services. Last year's plan might have included dental coverage that's reduced or eliminated this year, or a plan might add new benefits like over-the-counter allowances, gym memberships, or meal delivery that weren't available before. These benefit changes can substantially impact the value you receive.

Medicare Star Ratings: Understanding Quality Measures

Medicare's Star Rating system helps you compare Medicare Advantage and Part D plans based on quality and performance. Plans receive ratings from 1 to 5 stars, with 5 stars indicating excellent performance and 1 star indicating poor performance. These ratings, updated annually, provide valuable information beyond just costs and benefits.

Star ratings measure dozens of quality categories grouped into several domains. For Medicare Advantage plans, ratings assess staying healthy through screenings and vaccines, managing chronic conditions like diabetes and heart disease, member experience including customer service and claims processing, member complaints and appeals, and plan administrative performance.

For Part D plans, ratings evaluate drug plan customer service, member complaints and appeals, member experience with the drug plan, drug pricing accuracy, and patient safety measures. These comprehensive evaluations provide insight into how well plans actually deliver care and serve their members.

Plans with 5-star ratings during certain times of year offer a special benefit: 5-star Special Enrollment Periods. If a 5-star Medicare Advantage or Part D plan is available in your area, you can switch to it at any time during the year, not just during the Annual Enrollment Period. This provides exceptional flexibility if you discover a highly-rated plan that better meets your needs.

Star ratings directly impact plan quality bonuses from Medicare. Plans with 4 or more stars receive bonus payments from Medicare that they can use to offer enhanced benefits or lower premiums to members. This means higher-rated plans often provide better value—more benefits at lower costs—than lower-rated plans.

However, don't choose plans based solely on star ratings. A 5-star plan that doesn't include your doctors in its network or doesn't cover your medications affordably might serve you worse than a 3-star plan that includes all your providers and covers your drugs with low copays. Use star ratings as one factor in your decision-making, along with costs, coverage, networks, and formularies.

View star ratings on Medicare's Plan Finder tool at medicare.gov/plan-compare. The tool displays star ratings prominently for each plan and lets you sort plans by rating. You can also see detailed breakdowns showing how plans scored in each quality category, helping you understand specific strengths and weaknesses.

Step-by-Step Plan Comparison Strategy

Comparing Medicare plans effectively requires a systematic approach. Start preparations in September, before the enrollment period begins, so you're ready to review options as soon as the window opens October 15. Gather essential information including a complete list of all prescription medications with names, dosages, and frequencies, names and addresses of all doctors and specialists you see, preferred pharmacies where you fill prescriptions, and estimates of how often you typically visit doctors, have tests, or need medical services.

Step 1: Use Medicare's Plan Finder Tool - Visit medicare.gov/plan-compare and enter your ZIP code. The tool shows all available Medicare Advantage and Part D plans in your area. Enter all your current medications to get personalized cost estimates. The Plan Finder calculates your total estimated annual costs including premiums, deductibles, and drug copays for each plan, providing the most accurate comparison available.

Step 2: Review Your Current Plan's Changes - Your current plan must mail you an Annual Notice of Change (ANOC) by September 30, detailing all changes to benefits, costs, coverage, and networks for the coming year. Read this notice carefully. Compare next year's plan details to what you had this year, looking specifically for premium changes, deductible changes, changes to copays or coinsurance, formulary changes affecting your medications, and network changes affecting your doctors.

Step 3: Identify Your Top Priorities - Determine what matters most for your situation. This might include keeping specific doctors and hospitals, minimizing total annual costs, having low monthly premiums, covering specific medications affordably, accessing extra benefits like dental or vision, having broad provider networks for flexibility, or receiving high-quality care indicated by star ratings.

Step 4: Compare Top Options - The Plan Finder tool lets you select multiple plans for detailed side-by-side comparison. Choose 3-5 plans that appear promising based on your priorities. Compare their total estimated annual costs (the most important figure), monthly premiums, deductibles, doctor and hospital copays, prescription drug coverage and costs, provider networks, extra benefits, and star ratings.

Step 5: Verify Crucial Details - Before finalizing your decision, verify that all your doctors and hospitals participate in the plan's network. You can check provider directories on plan websites or call providers' offices directly to confirm participation. Check that all your medications are on the plan's formulary without excessive restrictions. Confirm your preferred pharmacies are in the plan's network and whether they're preferred or standard pharmacies (preferred usually means lower copays).

Step 6: Read the Evidence of Coverage - Every plan provides a detailed Evidence of Coverage document explaining exactly what's covered, what you pay, and how the plan works. Review this document for plans you're seriously considering, paying particular attention to sections covering services you use frequently or any services you anticipate needing based on your health status.

Common Annual Enrollment Mistakes to Avoid

Many Medicare beneficiaries make preventable mistakes during the Annual Enrollment Period. Avoid these pitfalls to ensure you select the best coverage. The most common error is not reviewing plans at all—simply allowing coverage to automatically continue unchanged. While automatic renewal is convenient, it often results in paying more than necessary or having suboptimal coverage due to plan changes.

Choosing plans based solely on monthly premium is another frequent mistake. A $0 premium Medicare Advantage plan might seem ideal, but if it has a $1,500 deductible, high copays, and expensive drug coverage, it could cost far more annually than a plan with a $30 monthly premium but much lower cost-sharing. Always compare total estimated annual costs, not just premiums.

Failing to verify provider networks causes problems when beneficiaries discover after enrollment that their longtime doctors don't participate in their new plan. Always confirm your doctors are in-network before switching plans. Network directories can be outdated, so call doctors' offices directly to verify they accept the plan you're considering.

Ignoring prescription drug coverage proves costly for those who take regular medications. Some people select Medicare Advantage plans without carefully reviewing formularies, only to discover their medications are expensive or require frustrating prior authorization. Always enter all your medications into the Plan Finder tool and review the formulary for any plan you're considering.

Switching plans too frequently can be problematic. While you can change plans every year, constantly switching means repeatedly learning new plan rules, potentially changing doctors, and dealing with new customer service departments. Stability has value. Only switch if you find meaningfully better coverage or significantly lower costs.

Missing the December 7 deadline entirely is perhaps the most serious mistake. If you miss this deadline, you're generally stuck with your current coverage for the entire following year unless you qualify for a Special Enrollment Period. Mark your calendar and start the comparison process early to avoid last-minute rushing.

Special Situations and Exceptions

Some Medicare beneficiaries have special situations affecting their Annual Enrollment Period strategy. If you receive Extra Help (the Low-Income Subsidy) for Part D costs, you can switch Part D plans or join a Medicare Advantage plan with drug coverage monthly during a Special Enrollment Period. This provides much more flexibility than other beneficiaries have, allowing you to switch if you find better coverage at any time.

Individuals who are dually eligible for Medicare and Medicaid can also switch plans monthly. This flexibility helps ensure dual eligible beneficiaries can always access plans that meet their needs as their healthcare situations change.

If you're moving to a new address outside your current plan's service area, you qualify for a Special Enrollment Period to select new coverage when you move. Don't wait for the Annual Enrollment Period if you're moving—use your move-based Special Enrollment Period to get appropriate coverage in your new location immediately.

People with End-Stage Renal Disease (ESRD) have additional considerations. Recent policy changes now allow most Medicare beneficiaries with ESRD to enroll in Medicare Advantage plans, greatly expanding options. If you have ESRD, carefully review which plans in your area accept ESRD enrollees and cover dialysis and transplant services comprehensively.

For those currently in employer or union group coverage, understand how your retiree coverage coordinates with Medicare. Some employer plans serve as primary coverage, while others are secondary to Medicare. Verify whether dropping or changing your Medicare coverage would affect your employer coverage before making changes during the Annual Enrollment Period.

Getting Personalized Help with Plan Selection

You don't have to navigate the Annual Enrollment Period alone. Multiple free resources provide personalized assistance. State Health Insurance Assistance Programs (SHIP) offer the most valuable service—free, unbiased, one-on-one counseling from trained volunteers who help you compare plans based on your specific situation. SHIP counselors can walk you through the Plan Finder tool, explain plan differences, and help you understand complex coverage details. Find your local SHIP at shiphelp.org or by calling 1-800-MEDICARE (1-800-633-4227).

Medicare's national helpline, 1-800-MEDICARE, provides direct assistance from Medicare representatives who can help you compare plans, explain coverage rules, answer questions about the enrollment process, and help you enroll in new coverage over the phone if desired. The helpline operates 24 hours a day, seven days a week.

Many insurance agents are licensed to sell Medicare plans and can provide information about available options. However, remember that agents typically represent specific insurance companies and earn commissions on plans they sell, which may influence their recommendations. For truly unbiased assistance, use SHIP counselors or Medicare's own resources.

Some beneficiaries benefit from working with independent Medicare advisors who charge fees for their services but provide comprehensive plan analysis and ongoing support. These advisors don't receive insurance company commissions, which can provide more objective guidance, though you'll pay out-of-pocket for their services.

Many community organizations, senior centers, libraries, and Area Agencies on Aging host Medicare education events during the Annual Enrollment Period. These free seminars provide overview information about plan options and can connect you with SHIP counselors for individual assistance.

After Enrollment: Confirming Your New Coverage

After you enroll in a new plan during the Annual Enrollment Period, confirm your enrollment was processed successfully. Your new plan should mail you a welcome packet and membership card by December 31, before your coverage begins January 1. If you don't receive these materials, contact the plan immediately to verify your enrollment.

During late December, contact your doctors' offices to provide your new insurance information. Schedule early January appointments for prescription refills or ongoing care to ensure smooth continuity. Keep your old insurance card accessible through December 31 in case you need care during the last days of December.

If you're switching from a Medicare Advantage plan back to Original Medicare, consider whether you want to add a Medigap policy. You don't have guaranteed issue rights just because you're leaving Medicare Advantage (unless you're within your first 12 months on Medicare Advantage), so you may face medical underwriting. Apply for Medigap coverage during the Annual Enrollment Period so it's ready to begin January 1 when you return to Original Medicare.

The Annual Enrollment Period is your opportunity to take control of your Medicare coverage. By reviewing options carefully, comparing plans based on your current needs, using available resources and tools, and avoiding common mistakes, you can ensure you have the best possible coverage at the most affordable cost for the coming year. Make the most of this important enrollment window to secure healthcare coverage that truly serves your needs.