What an enrollment period is and why it matters

An enrollment period is a window of time when you can sign up for Medicare or change your coverage. Medicare has several different enrollment periods throughout the year, and which one applies to you depends on your age, work status, and whether you already have coverage. If you miss your enrollment period, you may have to wait months or even a year before you can sign up, and you could face a permanent penalty on your premiums.

The enrollment periods exist because Medicare needs to manage when people join the program and when they switch plans. Understanding which period applies to you — and when it starts and ends — is one of the most important steps in getting Medicare coverage on time.

Key Takeaways

  • Your Initial Enrollment Period begins three months before the month you turn 65 and lasts for seven months total.
  • If you miss your Initial Enrollment Period, you will pay a permanent penalty on your Part B and Part D premiums for as long as you have Medicare.
  • The General Enrollment Period runs January 1 through March 31 each year, but you can only use it if you missed your Initial Enrollment Period.
  • If you already have Medicare, you can change plans during the Annual Enrollment Period from October 15 through December 7 each year.
  • Special Enrollment Periods are available if you lose employer coverage, move to a new state, or experience other may have access to life changes.

Your Initial Enrollment Period: the seven-month window when you first turn 65

Your Initial Enrollment Period is the first time you can sign up for Medicare, and it lasts for seven months. It begins three months before the month you turn 65 and ends three months after. For example, if you turn 65 in June, your period runs from March through September.

During this seven-month window, you can sign up for Part A (hospital insurance) and Part B (medical insurance). You can also choose a Medicare Advantage plan or a Medigap policy, and you can sign up for Part D (prescription drug coverage). The sooner you sign up during this period, the sooner your coverage begins — usually the first day of the month in which you turn 65, or the first day of the following month if you sign up after the 15th.

If you are still working and covered by your employer's health plan, you may be able to delay Part B without penalty, but you must still sign up for Part A during your Initial Enrollment Period. Talk to your employer's benefits office and to Medicare before you decide to delay.

What happens if you miss your Initial Enrollment Period

If you do not sign up for Part B during your Initial Enrollment Period, you will pay a late enrollment penalty for as long as you have Medicare. The penalty is 10 percent of the standard Part B premium for each full 12 months you were not enrolled. If you miss Part D, you will pay a penalty on your prescription drug coverage as well. These penalties do not go away — they are permanent.

You can still sign up after your Initial Enrollment Period ends, but you will have to wait for the General Enrollment Period or a Special Enrollment Period. In the meantime, you will have no Medicare coverage and will be responsible for all of your medical bills.

The General Enrollment Period: a second chance, but with limits

The General Enrollment Period runs from January 1 through March 31 each year. You can use it to sign up for Medicare if you missed your Initial Enrollment Period. Coverage begins July 1 of that year, so there is a gap between when you sign up and when your coverage starts.

You can only use the General Enrollment Period if you are not already enrolled in Medicare Part A or Part B. If you already have one part but not the other, you may be able to use this period to add the missing part, but the rules are complex. Contact Medicare directly to find out whether you can use the General Enrollment Period in your situation.

The Annual Enrollment Period: changing your plan if you already have Medicare

If you already have Medicare, the Annual Enrollment Period (also called the Open Enrollment Period) is when you can change your coverage. It runs from October 15 through December 7 each year. During this time, you can switch from Original Medicare to a Medicare Advantage plan, switch from Medicare Advantage to Original Medicare, change to a different Medicare Advantage plan, or change your Part D prescription drug plan.

Changes you make during the Annual Enrollment Period take effect on January 1 of the following year. You do not have to change plans every year — you can keep the same coverage if it still works for you. But if your plan is changing its costs or coverage, or if your health needs have changed, the Annual Enrollment Period is your chance to look at other options.

Special Enrollment Periods: when life changes open enrollment outside the regular windows

A Special Enrollment Period lets you sign up for Medicare or change your coverage outside the regular enrollment periods if you experience certain life events. These include losing employer coverage, moving to a new state, getting married or divorced, having a significant change in income, or being a victim of abuse or neglect.

The length of a Special Enrollment Period depends on the reason for it. Some last two months, others last longer. You must sign up within a specific timeframe after the event happens — for example, within two months of losing your job. If you wait too long, you will lose the chance to use that Special Enrollment Period and may have to wait for the General Enrollment Period or the next Annual Enrollment Period.

If you think you have experienced a may have access to life event, contact Medicare to find out whether you have a Special Enrollment Period and how long you have to use it.

How to sign up during your enrollment period

You can sign up for Medicare online at Medicare.gov, by phone at 1-800-MEDICARE (1-800-633-4227), or in person at your local Social Security office. You will need your Social Security number, proof of citizenship or legal residency, and information about any current health coverage you have.

If you are signing up for Part D or a Medicare Advantage plan, you will need to choose which plan you want. Medicare.gov has tools to compare plans based on your prescriptions, doctors, and hospitals. You can also call 1-800-MEDICARE to speak with someone who can help you compare plans and answer questions about your options.

Keep records of when you sign up and what coverage you chose. You will receive a Medicare card in the mail within two weeks. Check it carefully to make sure all the information is correct.

Frequently Asked Questions

What if I turn 65 while I am still working?

You can delay Part B if you have employer coverage through your job or your spouse's job, but you should still sign up for Part A. When you stop working or lose your employer coverage, you will have a Special Enrollment Period to sign up for Part B without penalty. Contact your employer's benefits office and Medicare before you decide to delay.

Can I change my Medicare plan more than once a year?

You can change plans during the Annual Enrollment Period once per year. If you experience a may have access to life event, you may have a Special Enrollment Period that lets you change plans outside the regular window. Some people with low income or disabilities have access to additional enrollment periods — contact Medicare to learn about you may have access to.

What is the penalty for missing my enrollment period?

The late enrollment penalty for Part B is 10 percent of the standard premium for each full 12 months you were not enrolled. The Part D penalty is 1 percent of the national average premium for each month you were not enrolled. These penalties are permanent and added to your monthly premium for as long as you have Medicare.

When should I sign up if my birthday is December 31?

If you turn 65 on December 31, your Initial Enrollment Period begins in September and ends in March of the following year. Sign up as early as possible in September so your coverage can begin on January 1 when you turn 65, rather than waiting until later in your enrollment period.

Do I have to sign up for all parts of Medicare at the same time?

You can sign up for different parts at different times, but each part has its own enrollment period and its own late penalty. Part A and Part B are separate, and Part D is separate from both. If you delay one part, make sure you understand the penalty rules for that specific part before you decide.