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What are the 3 Medicare enrollment periods?

Each of the three Medicare enrollment periods — initial, special and general — serves a different purpose, and you may qualify for more than one at different times in your life.

If you’re already receiving Social Security benefits at least four months before you turn 65, you won’t need to take advantage of any of those enrollment periods. You’ll be signed up automatically for Medicare, effective at the beginning of your birthday month or the start of the previous month if your birthday is on the first. You should receive your Medicare card in the mail three months before your coverage starts.

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If you don’t get Social Security yet, you need to sign up for Medicare. You can enroll only at certain times, so if you miss key deadlines, you could end up with late enrollment penalties and coverage gaps.

What is the Medicare initial enrollment period?

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If your birthday is anywhere within a month except the first day, your initial enrollment period begins three months in advance of the month you turn 65 and lasts until the end of the third month after.

Unless you qualify for Medicare early because of a disability, the first time you can enroll is during the seven-month initial enrollment period that starts three months before the month you turn 65 and ends three full months after your birthday month. Those with first of the month birthdays get a head start on initial enrollment four months beforehand, and their seven-month window ends two months after their birth month.

If you sign up before your birthday month, your coverage takes effect the first of the month you turn 65 or the beginning of the previous month if your birthday is on the first. If you enroll during your birthday month or three months afterward, coverage begins the first day of the following month.

The easiest way to sign up is on the Social Security Administration website. Your Medicare card and Welcome to Medicare package should come in the mail in about two weeks.  

If you qualify for premium-free Part A, which covers hospitalization, you can get coverage during or after your initial enrollment period without penalty. Your coverage is retroactive for up to six months but no earlier than the month you turned 65.  

If you don’t sign up for Part B during your IEP, you may have to wait until the general enrollment period Jan. 1 to March 31 each year.

You may face a late enrollment penalty unless you qualify for a special enrollment period. The penalty adds 10 percent to the standard Part B premium for each 12 months you could have had Part B but didn’t and lasts for as long as you have Part B.

You may also be required to pay a Part A late enrollment penalty if you don’t qualify for premium-free Part A.

Special rules for Puerto Rico: Residents of the largest and most populous U.S. territory are enrolled automatically in Part A if they’re already receiving Social Security but not Part B. Unless you or your spouse is still working and you have health insurance from that employer, you’ll need to sign up for Part B yourself during your initial enrollment period.

What is a Medicare special enrollment period?  

You have an extra opportunity to enroll in Part B after age 65 without a late enrollment penalty if you qualify for an SEP. You or your spouse must still work and have health insurance from that employer.

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You can enroll in Medicare any time while you have that coverage and up to eight months after the employment or coverage ends, whichever is first.

The coverage must be from a current employer. Continuing an employer’s coverage through COBRA or retiree health insurance doesn’t count.  

You can sign up online for Part B during a SEP. You’ll need to submit special forms that show you’ve been employed since your initial enrollment period ended.  

Be careful about coverage gaps. Even though you can qualify for a SEP if you have health insurance from an employer of any size, you may have coverage gaps if you work for an employer with fewer than 20 people and you don’t sign up for Medicare during your IEP.  

Coverage from most small employers becomes secondary to Medicare at 65, so it may not pay your bills if you don’t sign up for Medicare. Ask your employer about the company’s rules. However, coverage from an employer with 20 or more employees always pays before Medicare.

The SEP rules expanded Jan. 1, 2023. You can qualify for a special enrollment period in several other circumstances that occur on or after that date. The SEP generally lasts up to six months after the following situations:  

  • Inability to enroll in Medicare because of a natural disaster.
  • Loss of Medicaid coverage.
  • Misinformation from your employer, health plan agent or broker that kept you from enrolling.
  • A missed chance to sign up for Medicare while incarcerated.
  • Missed sign-up period because of circumstances out of your control.

Submit a special enrollment form if you’re enrolling because of one of these circumstances.  

What is a general enrollment period?

If you didn’t sign up for Medicare Part B during your initial enrollment period and you don’t qualify for a special enrollment period, the next general enrollment period is when you’ll be allowed to sign up. The GEP also applies if you missed your IEP and you don’t qualify for premium-free Part A.  

The general enrollment period runs Jan. 1 to March 31, and your coverage begins the first of the month after you sign up. You may have a to pay a late enrollment penalty.  

You can’t enroll online during a GEP. To enroll in Part B, you must complete Form CMS-40B and mail it or return it to a Social Security office.

See the Social Security Administration’s instructions or call SSA at 800-772-1213 for more information. You must call SSA if you need to enroll in both Part A and Part B during a GEP.

Keep in mind

These are enrollment periods to start Medicare Part A and Part B.

The time frames are different from Medicare’s annual open enrollment period, Oct. 15 to Dec. 7. Open enrollment allows you to sign up for or switch Part D prescription drug coverage or private Medicare Advantage plans.  

Published March 8, 2023

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