How to Enroll in Medicare Part C (Medicare Advantage)

Medicare Part C is enrollment through private insurance companies, not Medicare directly

Medicare Part C, also called Medicare Advantage, is a way to get your Medicare benefits through a private insurance company instead of through Original Medicare (Parts A and B). The private insurer is paid by Medicare to cover your hospital and medical costs. You enroll with the insurance company, not with Medicare itself, though Medicare sets the rules about what plans must cover.

You can enroll during specific windows each year, and the process differs depending on whether you are new to Medicare or already covered. The main enrollment periods are the Initial Enrollment Period (when you first turn 65), the Annual Enrollment Period (October 15 to December 7 each year), and the Medicare Advantage Open Enrollment Period (January 1 to March 31). Outside these windows, you can only switch plans if you have a may have access to life event.

Key Takeaways

You enroll directly with the insurance company offering the Medicare Advantage plan, not with Medicare, though you must be enrolled in Medicare Parts A and B first.
The Annual Enrollment Period runs October 15 to December 7 each year, and coverage starts January 1 of the following year.
You can compare plans on Medicare.gov, by phone at 1-800-MEDICARE, or through a local State Health Insurance information Program (SHIP).
Most Medicare Advantage plans include prescription drug coverage (Part D), dental, vision, and hearing benefits that Original Medicare does not cover.
You must stay enrolled in Medicare Parts A and B while you have a Medicare Advantage plan, and you pay the Part B premium to Medicare in addition to any plan premium.

Confirm you are enrolled in Medicare Parts A and B first

You cannot enroll in a Medicare Advantage plan unless you already have Medicare Part A (hospital insurance) and Part B (medical insurance). If you turned 65 and signed up for Medicare when you were first may be able to access, you likely have both. If you are unsure, log into your Medicare account at Medicare.gov, call 1-800-MEDICARE, or check your Medicare card — it will show whether you have Part A and Part B coverage.

If you do not have both parts yet, you must enroll in them before you can choose a Medicare Advantage plan. Part A is usually automatic at 65 if you are receiving Social Security. Part B requires a separate choice and has a monthly premium. Once you have both, you can then enroll in Part C through a private insurer.

Know the enrollment windows when you can switch plans

The Annual Enrollment Period is October 15 to December 7 each year. This is when anyone with Medicare can switch to a different Medicare Advantage plan, switch to Original Medicare, or make changes to their current plan. Coverage from any plan you choose during this window starts January 1 of the next year. This is the main window most people use.

The Initial Enrollment Period is the three months before, during, and after the month you turn 65. If you turn 65 in June, your Initial Enrollment Period runs March through August. During this window, you can enroll in a Medicare Advantage plan for the first time. If you miss this window and do not have a may have access to reason, you may face a late enrollment penalty.

The Medicare Advantage Open Enrollment Period runs January 1 to March 31 each year. If you are already enrolled in a Medicare Advantage plan, you can switch to a different Medicare Advantage plan, switch to Original Medicare, or drop your plan during this window. Changes take effect the first of the following month.

Outside these windows, you can only change plans if you have a may have access to life event — moving to a new state, losing other insurance, getting married or divorced, or a change in your income. You have 60 days from the event to make a change. Contact your current plan or 1-800-MEDICARE to report the event and see what options open up.

Compare plans and choose one that fits your needs

Medicare Advantage plans vary widely in cost, coverage area, and what doctors and hospitals are in-network. Most plans have a network — you pay less if you use doctors and hospitals in that network, and more or nothing if you go out of network. Some plans are Health Maintenance Organizations (HMOs), which require you to pick a primary care doctor and get referrals for specialists. Others are Preferred Provider Organizations (PPOs), which give you more flexibility to see specialists without a referral.

Use the Medicare Plan Finder tool at Medicare.gov to see which plans are available in your area, what they cost, and what they cover. You can filter by plan type, monthly premium, and whether specific doctors or hospitals are in-network. The tool also shows the plan's star rating — a score based on member satisfaction and plan performance. You can also call 1-800-MEDICARE and speak with a representative who can walk you through options, or contact your local State Health Insurance information Program (SHIP), which offers free counseling.

Pay attention to the monthly premium (what you pay to the insurance company), the annual deductible (what you pay out of pocket before the plan starts paying), and copays or coinsurance (what you pay per visit or service). Most Medicare Advantage plans include prescription drug coverage, dental, vision, and hearing benefits, but the details vary. Write down the top two or three plans and compare them side by side before deciding.

Enroll directly with the insurance company

Once you have chosen a plan, contact the insurance company directly to enroll. You can enroll online through the company's website, by phone, or in person at a local office if the company has one. The insurance company will ask for your Medicare number (on your Medicare card), your date of birth, and confirmation that you have Medicare Parts A and B.

Enrollment is free — the insurance company does not charge a fee to sign you up. You will receive a confirmation letter in the mail within two weeks. Keep this letter; it shows your plan name, member ID, and coverage start date. If you do not receive confirmation by the expected date, call the insurance company to check the status.

You can also enroll through Medicare.gov by clicking "Enroll" on the plan you chose in the Plan Finder tool. This routes your information to the insurance company, which will contact you to complete the process. Either way, the insurance company handles the enrollment, not Medicare.

Understand what happens to your coverage after you enroll

Your Medicare Advantage coverage starts on the first day of the month after the insurance company confirms your enrollment, or on January 1 if you enrolled during the Annual Enrollment Period. You will receive a new insurance card from the company with your member ID and plan details. Use this card when you see doctors or fill prescriptions — do not use your original Medicare card for medical visits, though you keep it for your records.

You continue to pay your Medicare Part B premium to Medicare each month (usually deducted from your Social Security check). You also pay any monthly premium the Medicare Advantage plan charges, if it has one. Many plans have zero premium, meaning you pay only the Part B premium. You are responsible for any copays, coinsurance, or deductibles the plan requires when you use medical services.

Your Medicare Advantage plan is active for the full calendar year. If you want to switch plans or go back to Original Medicare, you must wait until the next enrollment period unless you have a may have access to life event. If you move out of your plan's service area, you can switch plans outside the normal enrollment window.

Get help if you are unsure or need to make changes

If you have questions about which plan to choose, how to enroll, or whether a specific doctor is in-network, contact your State Health Insurance information Program (SHIP). SHIP is a free counseling service in every state, and counselors can walk you through your options without pushing you toward any particular plan. Find your state's SHIP at shiptalk.org or by calling 1-800-MEDICARE and asking for the referral.

You can also call 1-800-MEDICARE directly. Representatives can answer questions about plan coverage, help you compare plans, and explain the enrollment process. They cannot tell you which plan to choose, but they can give you the information you need to decide. The line is open 24 hours a day, seven days a week.

If you have already enrolled and want to switch plans, you can do so during the next enrollment period or if you have a may have access to life event. Contact your current plan or the new plan you want to join to start the process.

Frequently Asked Questions

Do I have to enroll in Medicare Part C, or can I stay on Original Medicare?

Medicare Advantage is optional. You can stay on Original Medicare (Parts A and B) and add a separate Medigap or Part D plan if you want. There is no penalty for not choosing Medicare Advantage. The choice is yours each year during the enrollment period.

What if my doctor is not in the plan's network?

If your current doctor is not in-network, you can usually see them but pay more out of pocket, or you can choose a different plan that includes your doctor. Use the Plan Finder tool to check whether specific doctors are in-network before you enroll. If your doctor leaves the network after you enroll, you may be able to switch plans outside the normal enrollment window.

Can I switch back to Original Medicare after I enroll in Medicare Advantage?

Yes. During the Annual Enrollment Period (October 15 to December 7) or the Medicare Advantage Open Enrollment Period (January 1 to March 31), you can switch to Original Medicare. If you switch, you may want to enroll in a Medigap plan to cover costs Original Medicare does not pay. You can also add a separate Part D prescription drug plan.

Do I still pay the Medicare Part B premium if I have Medicare Advantage?

Yes. You pay your Medicare Part B premium to Medicare every month, even if your Medicare Advantage plan has no additional premium. The Part B premium is separate from any premium the Medicare Advantage plan charges. Most people have the premium deducted from their Social Security check automatically.

What if I move to a different state?

If you move out of your plan's service area, you can switch to a different Medicare Advantage plan or Original Medicare outside the normal enrollment window. Contact your current plan or 1-800-MEDICARE within 60 days of your move to report the change and see what options are available in your new location.

This guide is for general information only and is not medical, financial, legal, or other professional advice. For decisions specific to your situation, consult a qualified professional. See our Editorial Policy.