You may first sign up for Medicare during a period that begins 3 months before your 65th birthday and ends 3 months afterward. There are other set enrollment periods throughout the year where you may make certain changes to your coverage.

For most people, signing up for Medicare begins during a 7-month initial enrollment period (IEP). The IEP starts 3 months before the month you turn 65 years old and continues for 3 months after it.

If you don’t sign up for Medicare coverage when you’re eligible, you may be subject to penalties in the form of higher costs when you do ultimately enroll.

In this article, we’ll provide specific information about your eligibility and the time frame for signing up for Medicare.

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There are various enrollment periods throughout the year that allow you to modify your Medicare coverage.

Medicare initial enrollment period

The Medicare IEP is a 7-month period that starts 3 months before your 65th birthday, includes your birthday month, and ends 3 months after your birthday. This is typically your first chance to enroll in Medicare.

During the IEP, you can sign up for Original Medicare (Part A and Part B), Medicare Advantage (Part C), a Part D prescription drug plan, or Medigap.

Medigap enrollment

Under federal law, there is a 6-month Medigap open enrollment period that starts the first month you have Medicare Part B and are 65 years or older.

Medigap is supplemental insurance that helps cover the out-of-pocket costs of Original Medicare.

General enrollment period

If you didn’t sign up for Medicare during the IEP, you can still enroll in Medicare parts A and B or a Medicare Advantage plan during the general enrollment period (GEP). The GEP takes place each year from January 1 to March 31.

If you first enroll in Medicare during the GEP, you may be subject to a late enrollment penalty on the cost of your monthly premiums.

Open enrollment period

The annual open enrollment period (OEP) takes place from October 15 to December 7 each year. During the OEP, Medicare beneficiaries can make a variety of changes to their coverage, such as adding, dropping, or switching Medicare Advantage or Part D plans.

Special enrollment period

Under certain conditions, you may be able to enroll in Medicare late during a window known as a special enrollment period (SEP).

SEPs may be given if you waited to sign up for Original Medicare because you had health insurance provided through your job, union, or spouse.

If so, you may apply for Medicare parts A and B within 8 months after your coverage ends or for Medicare parts C and D within 63 days after your coverage ends.

If you’re already receiving benefits from the Social Security Administration (SSA) or the Railroad Retirement Board (RRB), you don’t have to apply for Medicare. You’ll automatically be signed up for Medicare parts A and B as you near your 65th birthday.

If you’re not automatically enrolled, you’ll need to apply for Original Medicare and any additional coverage you want.

Original Medicare

You have several ways to enroll in Original Medicare:

  • Online: Visit SocialSecurity.gov to begin enrollment.
  • By phone: Call the SSA at 800-772-1213 (TTY: 800-325-0718), Monday through Friday, 8 a.m. to 7 p.m.
  • In person: Visit your local SSA office; you can find it through the SSA office locator.
  • By mail: Send a letter to your local SSA office with your name, your Social Security number, and the date you’d like to enroll. They will send you the necessary information and any additional requests for enrolling.

Medicare Advantage

You have two ways to sign up for Medicare Advantage:

  • Online: Shop for Medicare Advantage plans with Medicare.gov’s plan finder tool.
  • With a private company: Private insurance companies offer Medicare Advantage plans, and you can enroll directly with them via their website or by phone.

Medicare Part D

If you want to enroll in Medicare Part D, you have several ways to do so:

  • By phone: Call 800-633-4227 (TTY: 877-486-2048).
  • Online: Use Medicare.gov’s plan finder tool to compare Part D plans available in your area.
  • Contact a private insurance company: Contact private insurers that offer Part D plans via their website or by phone, and enroll directly with them.

When are you eligible for each part or plan in Medicare?

Here is an at-a-glance overview of when you’ll be eligible for each part of Medicare:

  • Part A: You’re first eligible to enroll in Medicare Part A during the IEP. You’ll be automatically enrolled in Part A at age 65 years if you’re currently receiving Social Security disability benefits or RRB disability benefits.
  • Part B: As with Part A, you’re first eligible to enroll in Part B during the IEP, and you’ll be automatically enrolled if you receive disability or retirement benefits.
  • Part C (Medicare Advantage): To enroll in Medicare Advantage, you must first have parts A and B. You can sign up for Medicare Advantage during the IEP or other enrollment periods.
  • Part D: You can enroll in a Part D prescription drug plan when you first get Medicare during the IEP. If you don’t sign up for Medicare Part D within 63 days of your IEP, you may incur a late enrollment penalty.
  • Medicare supplement (Medigap): The initial enrollment period for Medigap is triggered by the start of the month when you turn 65 years old and sign up for Part B. Initial enrollment for Medigap lasts for 6 months from that date.

If you’re currently receiving Social Security benefits and are under age 65 years, you’ll be automatically enrolled in Medicare parts A and B when you become 65. If you don’t wish to have Medicare Part B, you can defer it at that time.

If you’re not currently getting Social Security, you’ll have to actively enroll in Medicare.

Once you know the do’s and don’ts of signing up, the actual process is easy. The following factors are important to consider when enrolling in Medicare.

Your age

You may wish to put the wheels in motion by signing up for Medicare any time during the 3 months prior to your 65th birthday. You can also sign up during the month you turn 65, as well as throughout the 3-month period following that date.

It’s important to note that if you delay signing up until the final 3 months of the IEP, the start of your medical coverage may be delayed.

If you have a disability

If you’ve been receiving either Social Security disability benefits or RRB disability benefits for at least 24 consecutive months, you’re eligible to enroll in Medicare at any time, no matter your age.

If you have amyotrophic lateral sclerosis (ALS) or end stage renal disease (ESRD), you’re also eligible for Medicare at any time, independent of your age.

Your citizenship

In order to be eligible for Medicare, you must be a resident of the United States, AND you must either be a U.S. citizen or a permanent U.S. resident who has lawfully lived in the country for at least 5 continuous years prior to the month of filing an application for Medicare.

If you have a spouse

Unlike private health insurance plans, your spouse can’t be covered under your Medicare plan.

In order for your spouse to be covered, they must meet Medicare’s specific eligibility requirements, such as age. Once those requirements are met, they may be eligible for some Medicare benefits based on your work history, even if they didn’t work.

If your spouse is younger than you and will be losing their health insurance once you go on to Medicare, they may be able to purchase health insurance through a private provider.

If you’re approaching age 65 but would like to continue with the health insurance coverage you currently have through your spouse’s plan, you typically may do so without penalty.

You’re generally eligible to first sign up for Medicare starting 3 months prior to the month you turn 65 years old. This initial enrollment period (IEP) lasts for 7 months.

There are special circumstances and also other enrollment periods throughout the year during which you may first enroll — if you miss the IEP — or modify your coverage.