Who Can Enroll in Medicare Part C (Medicare Advantage)

The Basic Rule for Medicare Part C

You can enroll in Medicare Part C if you are already enrolled in both Medicare Part A (hospital insurance) and Medicare Part B (medical insurance). Part C, also called Medicare Advantage, is an alternative way to receive your Medicare benefits — it replaces Original Medicare and is offered by private insurance companies approved by Medicare.

You do not need to meet any income or health requirements beyond being a Medicare beneficiary. However, you must live in the service area where the plan operates. Each plan covers a specific geographic region, and you can only enroll if your home address falls within that region.

Most people become may be able to access for Medicare at age 65, but some younger people with disabilities or end-stage renal disease can also enroll in Medicare and therefore in Part C. If you are already on Original Medicare, you can switch to a Part C plan during certain enrollment periods.

Key Takeaways

You must be enrolled in both Medicare Part A and Part B before you can join a Medicare Part C plan.
There are no income limits or health screenings required to enroll in Part C, but you must live in the plan's service area.
You can enroll in Part C during your Initial Enrollment Period (when you first become may be able to access for Medicare), the Annual Enrollment Period (October 15 to December 7 each year), or the Medicare Advantage Open Enrollment Period (January 1 to March 31).
If you have end-stage renal disease, you may have different enrollment rules and should contact Medicare directly to understand your options.

When You First Become may be able to access for Medicare

Your Initial Enrollment Period is a seven-month window centered on your 65th birthday. It runs from three months before the month you turn 65 through three months after. During this time, you can enroll in a Medicare Advantage plan without waiting for an annual enrollment period.

If you delay enrolling in Part B when you first become may be able to access, you also delay your ability to enroll in Part C. Part C requires active enrollment in both Part A and Part B, so make sure Part B is in effect before you choose a Part C plan. If you miss your Initial Enrollment Period, you may face a permanent penalty on your Part B premium.

People under 65 with disabilities or end-stage renal disease have their own Initial Enrollment Period rules. If this applies to you, contact Medicare at 1-800-MEDICARE to learn the exact dates you can enroll.

Annual and Special Enrollment Periods

The Annual Enrollment Period runs from October 15 to December 7 each year. During this time, anyone already on Medicare can switch from Original Medicare to a Part C plan, switch from one Part C plan to another, or switch from Part C back to Original Medicare. Changes take effect on January 1 of the following year.

The Medicare Advantage Open Enrollment Period runs from January 1 to March 31 each year. If you are already enrolled in a Medicare Advantage plan, you can switch to a different Part C plan or return to Original Medicare during this window. Changes take effect on the first day of the month after you enroll.

If you experience a may have access to life event — such as moving out of your plan's service area, losing other health coverage, or becoming newly may be able to access for Medicaid — you may be able to enroll outside these regular periods. These are called Special Enrollment Periods, and they last 60 days from the date of the may have access to event.

Service Area and Plan Availability

Medicare Advantage plans are regional. Your address determines which plans are available to you. Some counties have many options; others have only one or two. You can search for plans in your area on Medicare.gov by entering your ZIP code.

If you move to a new address outside your current plan's service area, you have a 60-day Special Enrollment Period to switch to a different plan or return to Original Medicare. It is important to check plan availability before moving, because you may not have the same options in your new location.

Plans can also change their service areas from year to year. Even if a plan covered your address last year, it may not this year. During the Annual Enrollment Period, always verify that your current plan still serves your address.

Health Status and Pre-existing Conditions

Medicare Advantage plans cannot deny you enrollment or charge you more based on your health status or pre-existing conditions. This protection applies to all Medicare beneficiaries, regardless of age or medical history. You cannot be turned away because you have diabetes, heart disease, cancer, or any other condition.

However, some specialized plans — such as those focused on chronic conditions or specific diseases — may have different rules about which doctors and specialists you can see. These plans are still open to anyone who meets the basic Medicare may be able to access requirements, but they may require you to use their network providers.

If a plan denies your enrollment for any reason other than not living in the service area, contact Medicare at 1-800-MEDICARE to file a complaint.

What Happens After You Enroll

Once you enroll in a Medicare Part C plan, your coverage begins on the first day of the month after you enroll (or January 1 if you enrolled during the Annual Enrollment Period). Your plan will send you a welcome packet with your member ID card, plan documents, and a list of in-network doctors and hospitals.

You are required to use your Part C plan's network providers for most care. If you see an out-of-network doctor without authorization, you may have to pay the full cost yourself. Some plans allow out-of-network emergency care, but the rules vary by plan.

Your Part C plan replaces your Original Medicare coverage. You do not need a Medigap (supplemental) policy while you are on Part C, and in fact, it is illegal for an insurance company to sell you Medigap coverage while you are enrolled in Part C.

Questions to Ask Your Doctor or Medicare

Before you enroll in a Part C plan, ask your current doctor whether they are in the plan's network. Ask whether any specialists you see regularly are included. Find out what the plan's copayments are for the services you use most often.

Contact Medicare at 1-800-MEDICARE if you have questions about your enrollment period, your service area, or whether you meet the basic requirements for Part C. You can also visit Medicare.gov to compare plans side by side and read reviews from other members.

If you are unsure whether Part C is right for you, ask whether your State Health Insurance information Program (SHIP) offers free counseling. SHIP counselors can review your specific situation and help you understand the differences between Part C and Original Medicare.

Frequently Asked Questions

Can I enroll in Part C if I have not yet turned 65?

Yes, if you are under 65 and have been receiving Social Security Disability Insurance (SSDI) for at least 24 months, or if you have end-stage renal disease or ALS. You become may be able to access for Medicare two years after your disability begins (or when ready if you have ALS). Contact Medicare at 1-800-MEDICARE to confirm your may be able to access date and enrollment options.

What if I miss the Annual Enrollment Period?

If you miss the October 15 to December 7 window, you cannot change your coverage until the next Annual Enrollment Period arrives, unless you experience a may have access to life event such as moving or losing other insurance. Plan ahead and mark your calendar so you do not miss the important date.

Do I lose my Part C coverage if I move?

If you move within your plan's service area, your coverage continues. If you move outside the service area, your plan will end on the last day of the month you move. You have 60 days to enroll in a new plan or return to Original Medicare. Contact your plan and Medicare as soon as you know your move date.

Can a Part C plan refuse to cover a treatment my doctor recommends?

Part C plans can require prior authorization for certain treatments and may deny coverage if they determine a treatment is not medically necessary. If your plan denies coverage, you have the right to appeal. Ask your doctor to help you file an appeal and explain why the treatment is necessary for your condition.

What if I want to switch back to Original Medicare?

You can switch back to Original Medicare during the Annual Enrollment Period (October 15 to December 7) or the Medicare Advantage Open Enrollment Period (January 1 to March 31). If you switch, consider whether you need a Medigap policy to cover costs that Original Medicare does not pay.

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.