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Medicare Enrollment Periods, Dates & Deadlines

Published December 12, 2022

Enrollment in Medicare may seem confusing because so many enrollment periods sound the same, but they’re far easier to understand if you divide the enrollment process into two situations:

  1. You’re enrolling for the first time at age 65
  2. You’re switching from one program to another

Everything begins with signing up for Medicare itself, including enrolling in Original Medicare — which comprises Medicare Part A (hospital insurance) and Part B (medical insurance). Once you’re enrolled in Original Medicare, you can consider the following:

  • Replacing it with Medicare Part C (Medicare Advantage)
  • Purchasing an optional Medicare Supplement Insurance (Medigap) policy
  • Signing up for a Medicare Part D prescription drug plan, which only requires you to have Part A or Part B — not both

These first-time sign-ups take place within the following Medicare enrollment periods:

  • Initial Enrollment Period (IEP): Your personal seven-month enrollment period that occurs around your 65th birthday
  • Medicare Supplement Open Enrollment Period: A six-month period that starts on your 65th birthday — and a few other qualifying reasons — during which you can enroll in any Medigap policy that’s available in your state

Switching from one program to another takes place during these enrollment periods:

  • Annual Enrollment Period (AEP): A 54-day period during which you can switch your current Medicare Advantage plan or prescription drug plan for another one
  • General Enrollment Period (GEP): a three-month period that allows you to sign up for Part A, Part B, or both if you didn’t do so during your IEP
  • Special Enrollment Period (SEP): A unique enrollment period that occurs if you experience certain qualifying life events
  • Medicare Advantage Open Enrollment Period (MA OEP): a three-month period that allows you to change your current Medicare Advantage plan or drop it to return to Original Medicare

Each period will be explored — in that order — so you know where to focus your attention and make the best choices for your Medicare healthcare coverage.

Initial Enrollment Period (IEP)

The Initial Enrollment Period (IEP) is your first opportunity to sign up for Medicare. Your eligibility begins three months before the month you turn 65, includes your birth month, and ends three months after — for a total of seven months. For example, if your birthday falls in June, your IEP starts on March 1 and ends on September 30. However, if your birthday is on the first of the month, it shifts eligibility earlier. For example, if your birthday falls on July 1, your IEP starts on March 1 and ends on September 31. You can sign up any time within those seven months, but when you enroll will affect when your coverage begins:

  • If you sign up before the month you turn 65, your Medicare coverage will start on your birth month
  • If you sign up the month you turn 65 or during the next three months, coverage starts the month after you sign up

Medicare coverage always begins on the first day of the month.

You may be eligible for Medicare before you reach 65 if you have disabilities or certain diseases. Timing and eligibility requirements will vary for younger beneficiaries. You can use the Medicare eligibility tool to see if you are eligible and to determine your premium.

Medicare is made up of several parts, and in order to understand each type of enrollment period, it’s essential to understand how each part works.

Part A: Hospital Insurance

Medicare Part A is available to individuals aged 65 or older or to younger people with:

  • Specific disabilities
  • Permanent kidney failure
  • Amyotrophic lateral sclerosis (ALS, also known as Lou Gehrig’s disease)

Premium-Free Part A

Part A can be available to you either premium-free or with a premium. It is premium-free if you or your spouse paid Medicare taxes on income earned while working for at least 10 years. Two other situations grant premium-free Part A:

  • You or your spouse were Medicare-covered government employees
  • You are receiving — or are eligible to receive — Social Security or Railroad Retirement Board (RRB) benefits

You can sign up for premium-free Part A anytime after age 65. You may still be able to get Part A premium-free without the Medicare tax payments if:

  • You’re under 65 but qualify through 24 or more months of disability benefits from Social Security or the RRB
  • By needing kidney dialysis or being a transplant patient

Even if you have health coverage through your or your spouse’s work, you may still want to sign up for premium-free Part A at age 65. However, you may hold off signing up for Part B and its premium until your health coverage ends.

Premium-Paid Part A

If neither you nor your spouse has paid Medicare payroll taxes as required, but you are a U.S. citizen or permanent resident over the age of 65, you may be able to opt for Part A coverage by paying a monthly premium. The monthly premium amount will depend on how many quarters you or your spouse paid Medicare payroll taxes and can range from $278 to $506 in 2023.

With premium-paid Part A, if you decide not to sign up during your IEP, you’ll have to wait until the next General Enrollment Period (GEP), which starts on January 1 of the following year. However, if you wait until then and don’t have creditable health coverage elsewhere, which meets Medicare’s standards, your monthly premium could be increased by 10% when you do sign up. The penalty would remain in effect for double the number of years you waited to sign up.

You will be automatically enrolled in premium-free Part A and Part B if you have received Social Security or RRB benefits for four or more months before becoming eligible for Medicare. The exception is Puerto Rican residents that receive Social Security benefits, who will only be eligible for automatic enrollment in Part A. Otherwise, you must contact Social Security to apply for coverage. If automatically enrolled, you can choose to keep or refuse the coverage.

Part B: Medical Insurance

Medicare Part B is a voluntary program with a mandatory monthly premium payment for all the months you’re covered. Social Security sets the Part B premium, deductible, and coinsurance rates each year. In 2023, the Part B premium is $164.90, but yours could be higher based on your income. Eligibility for Part B depends on whether your Part A eligibility is premium-free or premium-paid.

If you’re eligible for premium-free Part A, you may also enroll in Part B once entitled to Part A. If you have to pay for Part A, you can get Part B if you are age 65 and meet the citizenship or resident qualifications. If you’re under 65, you can qualify by having a disability or kidney disease.

If you don’t enroll in Medicare Part B during your IEP, you can sign up during the GEP, which starts on January 1 next year. However, your premium may increase with a late-enrollment penalty of 10% for each year you remain uncovered, which you will pay for as long as you have Part B. An exception is granted if you have creditable health insurance through your or your spouse’s job, in which case you will have an eight-month window to enroll without penalty after your coverage ends.

Part C: Medicare Advantage

Once you enroll in Part A and Part B during your IEP, you can replace them with a Part C (Medicare Advantage) plan. These private plans provide everything Original Medicare does. They also provide built-in Part D prescription drug coverage and additional benefits such as dental and vision.

If you sign up before your Medicare starts, your Part C plan is effective the same day as your Original Medicare plan had you not replaced it. If your Medicare has already started when you ask to join a Medicare Advantage plan, coverage starts the first of the month after the plan provider gets your request.

If you sign up during your IEP, you can switch to another Medicare Advantage plan or move to Original Medicare within the first three months you have Medicare coverage.

If you don’t switch from Original Medicare to Medicare Advantage during your IEP, you can join, switch, or drop your Medicare Advantage plan during the Annual Enrollment Period from October 15 to December 7 each year. Still, you won’t pay any penalty because you will have had Original Medicare coverage in the interim.

If you have Medicare Advantage, you can make a one-time change to a different Medicare Advantage plan or switch back to Original Medicare during the Medicare Advantage Open Enrollment Period between January 1 to March 31.

Part D: Prescription Drug Coverage

Once you’ve enrolled in Part A and/or Part B during your IEP, you can sign up for a standalone Part D prescription drug plan via a private insurer to accompany Original Medicare, which doesn’t cover most medications. If you’ve opted for Medicare Advantage, your drug plan will likely already be bundled in, and standalone Part D plans are unavailable to you.

You’re not required to enroll in a Part D plan. However, if you decide to enroll after your IEP has ended and you go 63+ days without creditable drug coverage, you may face a penalty. Your monthly premium will be increased by 1% for each month you lack coverage — for example, 12% per year — payable for as long as you have Part D coverage. The penalty calculation uses the national base beneficiary premium, which is $32.74 in 2023, with an upcharge to your premium based on your income. You may avoid the penalty if you qualify for financial assistance such as Extra Help.

Medicare Supplement Insurance (Medigap)

Suppose you have Original Medicare and are concerned about the 20% of approved Medicare costs not covered under Part B. In that case, you may add a private Medicare Supplement Insurance (Medigap) policy. If so, your IEP is the best time to do so. Once you reach age 65 and are enrolled in Part B, you have a six-month Medigap Open Enrollment Period to buy any Medigap policy that’s available in your state without consideration of any pre-existing conditions. Beyond that period, existing health conditions can result in higher premiums or rejected applications.

Medicare Supplement Open Enrollment Period

If you have Original Medicare and would like to lower your share (20%) of approved medical expenses not paid by Medicare, a Medicare Supplement insurance (Medigap) policy can help. Private insurance companies offer these plans according to Medicare regulations.

Once you’re 65 and are enrolled in Part B for the first time, you have a six-month Medicare Supplement Open Enrollment Period to enroll in any Medigap policy available in your state, regardless of any pre-existing conditions. Insurers must accept your application, and your premiums cannot be increased due to your health.

However, suppose you’re under 65 and have Original Medicare early because of a disability or disease. In that case, you may not be eligible to buy a Medigap policy in your state, or you may have to pay a higher premium.

If you miss enrolling during your six-month window, you can enroll for a Medigap policy any time of the year. However, the insurance company can consider your health history when determining your premiums or whether to offer you coverage.

Annual Enrollment Period (AEP)

The Annual Enrollment Period (AEP) — also called the Open Enrollment Period — runs from October 15 to December 7. If you already have a Medicare Advantage plan, you can change to a different plan or drop your Medicare Advantage plan in exchange for Original Medicare, and vice-versa. If you return to Original Medicare, you may want to join a Part D prescription drug plan. You can join, change, or leave a Part D drug plan.

Any changes made by December 7 — AEP’s Medicare enrollment deadline — are effective on January 1 of the following year.

Private insurance companies can change Medicare Advantage and Part D prescription drug plans when they renew their contracts with Medicare each year — including their cost, coverage, in-network providers, and preferred pharmacies. Plan holders can switch plans, too. Plan providers will send plan holders an “Annual Notice of Change” (ANOC) in late September, showing what has changed. If a plan no longer suits a member’s needs, new plans can be compared on Medicare’s website.

If you join a Medicare Advantage plan during an AEP, then change your mind, you can choose a different Medicare Advantage plan or go back to Original Medicare during the Medicare Advantage Open Enrollment Period (MA OEP) from January 1 to March 31 every year.

General Enrollment Period (GEP)

AEP deals with changes to Medicare Advantage and Part D plans. Alternatively, the General Enrollment Period (GEP) deals with Medicare Part A and Part B. The GEP runs between January 1 to March 31 and allows you to sign up for Part A and/or Part B if you didn’t do so during your IEP. Starting January 1, 2023, your coverage begins the month after you sign up.

Eligibility to enroll in Part A or Part B is the same as it was during your IEP. The primary difference is that you may be subject to late-enrollment penalties in the form of increased premiums if you didn’t have other creditable health coverage in the interim. For premium-paid Part A, your monthly premium could increase by 10% when you do sign up, and the penalty would remain in effect for twice the number of years you waited to sign up. For Part B, your premium could increase by 10% for each year you remain uncovered, which will remain in effect for as long as you have Part B.

If you have Part A and only sign up for Part B during a GEP, you can also join a Medicare Advantage plan from April 1 to June 30, and your coverage will start on July 1. The only other time you can sign up is during a Special Enrollment Period (SEP). If you have creditable coverage through a job, you might sign up for premium-free Part A at age 65 — but you might hold off signing up for Part B with its premium. Then, when your job's coverage is ending, you would qualify for a SEP, at which time you could also join a Medicare Advantage plan.

If you don’t enroll in the first GEP after your IEP, you will have to wait until the next GEP, and you may continue to accumulate penalties unless you qualify for a SEP.

Special Enrollment Period (SEP)

A Special Enrollment Period (SEP) allows you to avoid penalties if you enroll late for Part B or premium-paid Part A. These exceptions are granted for various reasons — the most common being that you or your spouse are still employed when you turn 65 and you have group health insurance that is acceptable to Medicare. In that case, the SEP allows you to enroll in Part B anytime after you turn 65, as long as you have group coverage, and through the SEP’s eight months after you lose your job or coverage — whichever comes first.

If you don’t sign up within the SEP’s enrollment deadline, you’ll have to wait until the next GEP and likely face late-enrollment penalties in the form of higher premiums.

You may also qualify for a SEP in situations that let you change your Medicare Advantage plan, such as:

  • You moved outside of the service area of your current Medicare Advantage plan
  • Your Medicare Advantage provider stopped coverage in your service area
  • You qualify for financial assistance such as Medicaid or Extra Help

Medicare Advantage Open Enrollment Period (MA OEP)

Suppose you already have a Medicare Advantage plan. In that case, the Medicare Advantage Open Enrollment Period offers you a one-time chance to switch to a different plan, with or without drug coverage. You can also drop your Medicare Advantage plan and switch to Original Medicare, in which case you might want to join a Part D prescription drug plan.

This period runs from January 1 to March 31, and your changes become active during the first of the month after your new plan gets your request.

We’re Here to Help During Any Enrollment Season

Until you’re actually enrolled in Medicare and using its various parts, it seems to have a language of its own. Understanding the enrollment periods for Medicare adds another level of confusion. Whether you’re selecting a new plan or updating your current Medicare plan, you can visit our website or call (844) 910-2061 to be connected to a licensed insurance agent who can walk you through your options to help you make the best choices — while avoiding missed deadlines and penalties. OpenMedicare is here to help!


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