How to Sign Up for Medicare Advantage Plans

Where and When You Can Sign Up for Medicare Advantage

You can sign up for a Medicare Advantage plan through Medicare.gov, by phone at 1-800-MEDICARE, or directly with the insurance company offering the plan. The timing matters: you have three main windows to join without penalty. The Initial Enrollment Period runs for seven months starting the month you turn 65. The Annual Enrollment Period (also called Open Enrollment) runs from October 15 to December 7 each year — this is when most people switch plans or join for the first time. If you miss both windows, you may face a late enrollment penalty, though some life events (like losing employer coverage or moving to a new state) open a Special Enrollment Period lasting 60 days.

Plans you choose during October 15 to December 7 take effect January 1 of the following year. If you enroll outside the Annual Enrollment Period through a Special Enrollment Period, your coverage start date depends on when you complete your enrollment — it may be the first of the month after you sign up, or later.

Key Takeaways

You can enroll through Medicare.gov, by calling 1-800-MEDICARE, or directly with an insurance company, and the process takes 10 to 15 minutes online or by phone.
The Annual Enrollment Period (October 15 to December 7) is the main window to join or change plans, with coverage starting January 1.
You must already be enrolled in Medicare Part A and Part B before you can join a Medicare Advantage plan.
You will need your Social Security number, Medicare number, and information about any current prescriptions and doctors you want to keep.
Missing enrollment important date can result in a permanent monthly penalty added to your premiums, unless a life event qualifies you for a Special Enrollment Period.

What You Need Before You Start

Have your Medicare card in front of you — you will need your Medicare number. You will also need your Social Security number and a list of any prescription medications you currently take, including the name and dose. If you have specific doctors or hospitals you want to use, write down their names so you can check whether they are in the plan's network.

If you are still working and have health insurance through your employer, gather that information too. Some Medicare Advantage plans coordinate with employer coverage, and you may need to provide details about your group health plan. You do not need to cancel your employer coverage before enrolling in Medicare Advantage — the plan will tell you what happens next.

Signing Up Online Through Medicare.gov

Go to Medicare.gov and click "Find Care Providers and Suppliers" or use the Plan Finder tool. Enter your ZIP code and the plans available in your area will appear. Each plan shows the monthly premium, deductible, copays for doctor visits, and whether your doctors are in-network. Click on a plan to see more details, including which pharmacies it uses and what prescription drugs it covers.

Once you have chosen a plan, click "Enroll" on that plan's page. You will be asked to sign in with your Medicare.gov account — if you do not have one, you can create it using your email address and Medicare number. Follow the prompts to confirm your personal information, your current Medicare coverage, and any other insurance you have. At the end, you will see a confirmation number. Write it down or print the page.

The plan's insurance company will send you a welcome packet in the mail within two weeks, including your member ID card, plan documents, and a list of in-network doctors and pharmacies. Your coverage begins on the date shown in your confirmation.

Signing Up by Phone

Call 1-800-MEDICARE (1-800-633-4227). A representative will ask for your Medicare number, Social Security number, and date of birth to pull up your account. Tell them you want to enroll in a Medicare Advantage plan and give them your ZIP code. They will read you the plans available, explain the costs and coverage, and answer questions about specific doctors or medications.

The representative can enroll you over the phone. They will confirm your choice and give you a confirmation number before you hang up. Write down this number and the date and time of your call. You will receive your member ID card and plan documents by mail within two weeks.

Signing Up Directly With an Insurance Company

If you already know which insurance company you want to use — Humana, UnitedHealthcare, Anthem, Aetna, or another carrier — you can go directly to their website and look for their Medicare Advantage plans. Each company's site has an enrollment tool where you enter your ZIP code and see their available plans.

The enrollment process is similar to Medicare.gov: you choose a plan, sign in or create an account, confirm your information, and receive a confirmation number. Some insurance companies also have local agents who can enroll you in person or by phone. To find a local agent, call the insurance company's customer service number on any Medicare Advantage advertisement or search "[Company Name] Medicare Advantage agent near me."

What Happens After You Enroll

Once your enrollment is confirmed, you will receive your member ID card in the mail. Do not throw away your red, white, and blue Medicare card — you will still need it as proof of your Medicare coverage. Your new Medicare Advantage card will have a different number and will be your ID for doctor visits and prescriptions under the new plan.

Before your coverage starts, contact your current doctors to let them know you are switching plans. Ask whether they accept your new plan's insurance. If a doctor you want to see is not in-network, you can sometimes request an exception from the plan, though this is not always granted. If you are currently taking prescription medications, check the plan's formulary (drug list) on its website to confirm your medications are covered and at what cost.

If you change your mind within 14 days of enrolling, you can cancel and return to Original Medicare or switch to a different Medicare Advantage plan. After 14 days, you are locked in until the next Annual Enrollment Period (October 15 to December 7), unless a may have access to life event occurs.

If You Miss the Enrollment important date

If you do not enroll during your Initial Enrollment Period (the seven months starting when you turn 65) or during the Annual Enrollment Period, you may still be able to join a Medicare Advantage plan, but only if you have a may have access to life event. These events include losing employer coverage, moving to a new state, getting married or divorced, or having a significant change in income.

When a may have access to event happens, you have 60 days from the date of the event to enroll in a Medicare Advantage plan through a Special Enrollment Period. You will need to provide proof of the event — such as a letter from your employer, a lease showing your new address, or a marriage certificate. Contact Medicare at 1-800-MEDICARE to report the event and enroll.

If you miss all enrollment windows and do not have a may have access to event, you can still join a Medicare Advantage plan during the next Annual Enrollment Period, but you may owe a late enrollment penalty. This penalty is a small percentage added to your monthly premium for as long as you have Medicare Advantage coverage, even if you switch plans later.

Frequently Asked Questions

Do I have to be on Medicare Part B to join Medicare Advantage?

Yes. You must be enrolled in both Medicare Part A (hospital insurance) and Part B (medical insurance) before you can join a Medicare Advantage plan. If you have not yet enrolled in Part B, you will need to do that first through Medicare.gov or by calling 1-800-MEDICARE.

Can I enroll in a Medicare Advantage plan if I have Original Medicare and a Medigap policy?

Yes, but you should know that once you switch to Medicare Advantage, you will lose your Medigap coverage. Some people find it hard to get a new Medigap policy later if they leave Medicare Advantage, so think carefully before making the switch. You can ask the Medicare Advantage plan about its out-of-pocket costs to compare with your current Medigap coverage.

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

Most Medicare Advantage plans are HMOs or PPOs that require you to use in-network doctors for full coverage. If your doctor is out-of-network, you can ask the plan for an exception, but approval is not may provide. Some plans allow you to see out-of-network doctors at a higher cost. Before enrolling, call the plan and ask whether your specific doctors are in-network.

When does my Medicare Advantage coverage actually start?

If you enroll during the Annual Enrollment Period (October 15 to December 7), your coverage starts January 1 of the next year. If you enroll during your Initial Enrollment Period or through a Special Enrollment Period, your coverage usually starts the first of the month after you complete enrollment, though this varies by plan and enrollment date.

Can I change my mind after I enroll?

You have 14 days from the date you enroll to cancel without penalty and return to Original Medicare or switch to a different plan. After 14 days, you are locked in until the next Annual Enrollment Period in October, unless a may have access to life event occurs.

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.