You’re about to get Medicare! That’s great news because the program helps pay for your health care costs and brings peace of mind. But learning how Medicare works and how to apply can be overwhelming. This article breaks down the key Medicare enrollment periods, how they work, and helps you plan for your big enrollment day.

Medicare Initial Enrollment Period

Your first chance to enroll in Medicare is around age 65 when you have a seven-month window to apply. This is your Medicare Initial Enrollment Period. You can file for Original Medicare Parts A and B, or sign up for a private Medicare plan at any time during the three months before, the month of, and the three months after your 65th birthday.

Need coverage the month you turn 65? You should sign up in the three-month window before your birthday.

Take a deeper dive in our related article about all-things Medicare Initial Enrollment Period.

Medicare General Enrollment Period

If you don’t sign up for Medicare Part A and/or Part B when you’re eligible, you can apply for Medicare for the first time during the General Enrollment Period from Jan. 1 through March 31 every year. Coverage begins July 1.

This enrollment period is only available to people who didn’t sign up during their Initial Enrollment Period and who aren’t eligible for a Special Enrollment Period.

Note: You may have to pay a higher premium for Part A and/or Part B due to late enrollment.

Medicare Annual Enrollment Period (AEP)

Once you sign up for Original Medicare Part A and Part B, you are covered and don’t need to renew it. But every year, during the Medicare Annual Enrollment Period (also known as the Medicare Annual Election Period or open enrollment) you have an opportunity to change your Medicare health or prescription drug plan. This happens annually from Oct. 15 through Dec. 7. If you make a change during this enrollment period, your new plan benefits are effective Jan. 1 of the following year. If you are unhappy with your current coverage, you should take advantage of AEP to find a better fit for your current health care needs.

Learn more: Medicare Annual Enrollment Period Guide.

Medicare Special Enrollment Period (SEP)

Special situations may come up that give you the chance to sign up for or change your Medicare plan outside of your Initial Enrollment Period or the Annual Enrollment Period.

Who qualifies for a Special Enrollment Period?

There are several special cases that make you eligible for a Special Enrollment Period. Here are some common situations:

  • You move: If you move to an address outside your plan’s service area, into a nursing home, or you have different plan options at your new address, you’ll be able to apply for a new plan.
  • You want to switch to a 5-star Medicare plan: Every year, Medicare evaluates plans based on a 5-star rating system. Medicare considers these plans “excellent.” You can make the switch once to a 5-star plan anytime from Dec. 8 through Nov. 30 if one is available in your area.
  • You lose your current coverage: This applies if you or your spouse will retire or change to a job that doesn’t offer coverage. It doesn’t apply if your insurance company cancels your coverage because you didn’t pay your monthly premiums.
  • Your plan changes its contract with Medicare: Enrollment in a plan depends on the plan’s contract with Medicare, and for various reasons these contracts could change.

Your new coverage begins on the first day of the month after you sign up. If you retire before age 65, you won't be eligible for Medicare. However, there are other early retirement health insurance options you can explore.

Medigap Open Enrollment Period

Your Medigap Open Enrollment Period is the six-month window that begins the first day of the month you turn 65 and are enrolled in Part B. For example, if you turn 65 and are enrolled in Part B in January, you can buy a Medigap policy between January and June. This enrollment window can’t be changed or repeated.

During this open enrollment period, you can buy any Medigap policy sold in your state, even if you have health problems.

But after your open enrollment period, you may not be able to buy a Medigap policy depending on your health status and may be subject to a health review.

Your new coverage begins on the first day of the month after you sign up.

Medicare Advantage Open Enrollment Period

Medicare Advantage Open Enrollment happens every year from Jan. 1 to March 31. If you’re enrolled in a Medicare Advantage plan and want to make changes, you can do one of these:

  • Switch to a different Medicare Advantage plan with or without drug coverage
  • Go back to Original Medicare and, if needed, also join a Medicare prescription drug plan

Your new coverage begins on the first day of the month following the month you make a change and will be in effect for the rest of the year.

Learn more: Medicare Annual Enrollment Period Guide

Qualifying for Medicare before age 65

There are several life situations that can make you eligible to file for Medicare before age 65. These include:

Social Security disability

Social Security and Medicare are two different programs that offer those who qualify financial benefits – however, sometimes they can impact one another. For instance, if you have been receiving Social Security disability benefits for 24 months, you may be eligible for Medicare. If you’re entitled to monthly benefits based on an occupational disability and have been granted a disability freeze, you become eligible for Medicare on the 30th month after the date of the freeze.

Qualifying health conditions

If you’ve been diagnosed with ALS, you become immediately eligible for Medicare as soon as you start collecting Social Security disability insurance (SSDI) benefits.

If you have ESRD, also known as end stage kidney disease, and need regular dialysis or a kidney transplant, you’re eligible for Medicare. Coverage begins shortly after your first dialysis treatment.

Family relationships

Here are some less common qualifying situations based on your relationship with a Medicare recipient:

  • You are a disabled widow(er) under age 65
  • You are a disabled divorced widow(er) under age 65
  • You have disabled children

This type of Medicare coverage typically requires a 24-month waiting period.

Visit to find out more.

How to sign up for Medicare

You sign up for Original Medicare Part A and Part B through the Social Security Administration (SSA) or the Railroad Retirement Board (RRB).

  • If you aren’t yet getting Social Security or Railroad Retirement benefits, you need to apply for Medicare.
  • If you already get Social Security or Railroad Retirement benefits, the SSA or RRB will automatically sign you up for Medicare Part A and B so it’s effective the month of your 65th birthday.

How to apply for Medicare through Social Security

Apply online: The easiest way to file for Medicare is to complete an online application at It’s convenient to sign up from home. You can start and stop the application and save your information. After you submit your application, you’ll get a receipt to print and keep. You can also check the status of your application.

Apply in person: Visit your local Social Security office. You can find the nearest office with the Social Security office locator. They recommend that you make an appointment.

Apply by phone: Call Social Security at 800-772-1213 (TTY 800-325-0778).

How to apply for Medicare through the RRB

If you worked for the railroad, call the Railroad Retirement Board (RRB) at 877-772-5772 (TTY 711) or submit an online service request through the RRB website.

The best time to apply is during the Medicare Initial Enrollment Period. Or, you can sign up during the Medicare General Enrollment Period.

Note: If you are still working, you can still sign up for RRB Medicare coverage when you turn 65. No need to retire.

If you, or a family member, are already receiving a railroad retirement annuity, you will automatically be enrolled in Medicare Part A and B. Coverage begins when you turn 65.

Documents you’ll need to apply for Medicare

You can file for Medicare one of three ways: in person, online, or by phone. Each one requires slightly different documentation to enroll.

Documents needed if you sign up in person

  • An original or certified copy of your birth certificate or other proof of birth
  • Proof of United States citizenship or legal residency if not born in the U.S.
  • Your Social Security card if you are already receiving benefits
  • A copy of your most recent W-2 form(s) and/or self-employment tax return
  • U.S. military discharge papers if you served before 1968
  • Health insurance information

Documents needed if you sign up online

  • Date and place of birth (If born outside the U.S., you’ll need your birth country and Permanent Resident Card number)
  • Health insurance information

How do I know I’m enrolled in Medicare?

After you apply for Medicare, Social Security will review and process your application. They’ll contact you if they need more information.

When you’re approved for Medicare Part A and/or Part B, Social Security will send you a welcome packet that includes the following:

  • Your confirmation letter
  • Your red, white and blue Medicare ID card
  • A “Welcome to Medicare” booklet that walks you through decisions you may have to make with your Medicare coverage
  • The Medicare & You handbook

If you’ve applied for a private Medicare plan such as a Medicare Advantage, Medicare Cost, Medigap or Medicare Prescription Drug plan, when your enrollment is accepted you’ll get a separate confirmation letter and ID card.

Medicare helps pay for your health care costs and covers preventive care including a visit with your doctor each year. So once you get Medicare Part B, schedule your initial “Welcome to Medicare” visit with your doctor. And each year you get an “Annual Wellness Visit” with your doctor.