Javascript is not enabled.

Javascript must be enabled to use this site. Please enable Javascript in your browser and try again.

Skip to content
Content starts here


Leaving Website

You are now leaving and going to a website that is not operated by AARP. A different privacy policy and terms of service will apply.

What are the 3 Medicare enrollment periods?

The three Medicare enrollment periods — initial, special and general — are specific time frames when you can enroll in Medicare based on certain circumstances, such as choosing to delay enrollment if you continue working past age 65. As such, you may qualify for more than one at different times in your life.

You won’t need to take advantage of any of the enrollment periods if you’re receiving Social Security benefits at least four months before you turn 65, in which case you’ll be signed up automatically for Medicare. Your enrollment is 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.

If you don’t get Social Security yet, you need to sign up for Medicare. You can enroll only during one of these three periods, and if you miss deadlines, you could end up with late enrollment penalties and coverage gaps.

spinner image Image Alt Attribute

AARP Membership— $12 for your first year when you sign up for Automatic Renewal

Get instant access to members-only products and hundreds of discounts, a free second membership, and a subscription to AARP the Magazine.

Join Now

What is the Medicare initial enrollment period?

spinner image illustration of initial enrollment period
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’re eligible to enroll is during the seven-month initial enrollment period that starts three months before the month you turn 65 and ends three months after your birthday month. If your birthday is on the first of the month, your initial enrollment period is shifted one month earlier.

By signing 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 two weeks after enrolling.  

Qualifying for premium-free Part A, which covers hospitalization, will ensure 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 from 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 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 Puerto Rico 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 a special enrollment period. The most common reason for a SEP is if you or your spouse are still working and have health insurance from that employer.

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.


AARP® Vision Plans from VSP™

Exclusive vision insurance plans designed for members and their families

See more Insurance offers >

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 special enrollment period but you’ll need to submit special forms to show you’ve been employed since your initial enrollment period ended.  

Be careful about coverage gaps. Even though you 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 initial enrollment period.  

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 company rules. However, coverage from an employer with 20 or more employees always pays before Medicare.

SEP rules expanded Jan. 1, 2023. You can qualify for a special enrollment period in other circumstances that applied 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.

You’ll need to submit a special enrollment form in the case of any of these circumstances.  

spinner image membership-card-w-shadow-192x134


Get instant access to members-only products and hundreds of discounts, a free second membership, and a subscription to AARP the Magazine.

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, your next chance is during the general enrollment period. You can also enroll at this time 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 each year. Your coverage begins the first of the month after you sign up but you may have to pay a late enrollment penalty.  

Video: How Do I Apply for Medicare?

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 general enrollment period.

Keep in mind

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

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

Return to Medicare Q&A main page

Discover AARP Members Only Access

Join AARP to Continue

Already a Member?