One of the most confusing aspects of Medicare is knowing when you can enroll or make changes to your coverage. Medicare has multiple enrollment periods, each with different rules about what you can do and when. Missing the right window can mean going without coverage, facing permanent penalties, or being stuck in a plan that does not meet your needs for an entire year. This guide explains every Medicare enrollment period — with specific dates and practical advice for North Carolina residents.

Medicare Enrollment Periods at a Glance

Enrollment Period When Who It Is For What You Can Do
Initial Enrollment Period (IEP) 7-month window around 65th birthday People turning 65 Enroll in Parts A, B, C, D, Medigap
Annual Enrollment Period (AEP) Oct 15 – Dec 7 each year All Medicare beneficiaries Switch MA/Part D plans, join or leave MA
MA Open Enrollment Period (OEP) Jan 1 – Mar 31 each year Current MA enrollees only Switch MA plans or return to Original Medicare
General Enrollment Period (GEP) Jan 1 – Mar 31 each year People who missed their IEP Enroll in Part A and/or Part B (penalties may apply)
Special Enrollment Periods (SEPs) Varies by qualifying event People with qualifying life events Enroll in or change Medicare coverage
Medigap Open Enrollment 6 months starting when Part B begins New Part B enrollees Buy any Medigap plan (guaranteed issue)

Let us look at each enrollment period in detail.

Initial Enrollment Period (IEP)

The Initial Enrollment Period is your first and most important opportunity to enroll in Medicare. It is a 7-month window centered on the month you turn 65:

  • Months 1–3: The 3 months before your 65th birthday month
  • Month 4: Your 65th birthday month
  • Months 5–7: The 3 months after your 65th birthday month

Example: Birthday in July 2026

IEP Month Calendar Month Coverage Start Date (if you enroll this month)
Month 1 April 2026 July 1, 2026
Month 2 May 2026 July 1, 2026
Month 3 June 2026 July 1, 2026
Month 4 (birthday) July 2026 August 1, 2026
Month 5 August 2026 September 1, 2026
Month 6 September 2026 October 1, 2026
Month 7 October 2026 January 1, 2027
Enroll Early for the Best Start Date The lesson is clear: enroll during the first 3 months of your IEP to get coverage starting the 1st of your birthday month. Waiting until later in your IEP can delay your coverage by up to 3 months, leaving you without Medicare during that gap.

What You Can Do During Your IEP

  • Enroll in Medicare Part A (hospital insurance)
  • Enroll in Medicare Part B (medical insurance)
  • Join a Medicare Advantage plan (Part C)
  • Join a Medicare Part D prescription drug plan
  • Buy a Medigap (Medicare Supplement) plan during your Medigap Open Enrollment (starts when Part B is effective)

Your IEP is the only time you can make all of these enrollment decisions simultaneously and without restrictions. For a detailed walkthrough, see our Turning 65 in North Carolina guide.

Annual Enrollment Period (AEP)

The Annual Enrollment Period, also called "Fall Open Enrollment," is the primary opportunity each year for all Medicare beneficiaries to make changes to their coverage.

Dates: October 15 – December 7 (Every Year)

Changes made during AEP take effect January 1 of the following year.

What You Can Do During AEP

  • Switch from one Medicare Advantage plan to another
  • Switch from Medicare Advantage to Original Medicare
  • Switch from Original Medicare to Medicare Advantage
  • Join a Medicare Part D plan for the first time (if not in one)
  • Switch from one Part D plan to another
  • Drop Part D coverage (though this may trigger a late penalty if you later re-enroll)

What You Cannot Do During AEP

  • Enroll in Part A or Part B (that is done through the IEP or GEP)
  • Buy or change a Medigap plan (Medigap has its own enrollment rules)
The AEP Is Your Annual Check-Up for Coverage Every September, your current plan sends you an Annual Notice of Change (ANOC) outlining what will change next year — premiums, formularies, networks, and benefits. Use this document to evaluate whether your current plan is still the best fit. Then use the AEP to make a switch if something better is available. Not reviewing your plan annually is one of the costliest Medicare mistakes — see 5 Medicare Mistakes That Could Cost You Thousands.

Need Help During the Enrollment Period?

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Medicare Advantage Open Enrollment Period (OEP)

Dates: January 1 – March 31 (Every Year)

The Medicare Advantage Open Enrollment Period is a less well-known enrollment window that provides a second chance for people enrolled in Medicare Advantage plans to make changes after the AEP has ended.

Who Can Use the OEP

Only people who are currently enrolled in a Medicare Advantage plan on January 1 can use the OEP. If you are on Original Medicare, the OEP does not apply to you.

What You Can Do During OEP

  • Switch from one Medicare Advantage plan to a different Medicare Advantage plan
  • Drop your Medicare Advantage plan and return to Original Medicare (and join a standalone Part D plan)

What You Cannot Do During OEP

  • Join a Medicare Advantage plan for the first time (you must already be in one)
  • Switch from Original Medicare to Medicare Advantage (that is done during AEP)
  • Buy or change a Medigap plan (underwriting may apply outside your Medigap OEP)

The OEP is useful as a “safety net” if you joined a Medicare Advantage plan during the AEP and quickly realized it is not working for you — perhaps your doctor is not in the network, or your medications are not covered as expected.

General Enrollment Period (GEP)

Dates: January 1 – March 31 (Every Year)

The General Enrollment Period is for people who missed their Initial Enrollment Period and did not have qualifying coverage to delay enrollment. If you should have enrolled in Part A or Part B when you turned 65 but did not, the GEP is your annual opportunity to sign up.

Key Details

  • Coverage starts July 1 of the year you enroll during the GEP
  • Late enrollment penalties will apply if you delayed without qualifying coverage
  • Once your Part B is effective, you can then enroll in a Medicare Advantage plan or Part D plan
Avoid the GEP If Possible The GEP is a last resort. Enrolling through the GEP means your coverage will not start until July 1, leaving you without Medicare for the first half of the year. It also means you will pay permanent late enrollment penalties. The far better approach is to enroll during your IEP or an applicable SEP.

Special Enrollment Periods (SEPs)

Special Enrollment Periods are triggered by specific life events that allow you to make changes to your Medicare coverage outside of the regular enrollment periods. Understanding SEPs is crucial because they are often your only opportunity to change coverage when a life event occurs.

Employer Coverage SEP

This is the most common and most important SEP. If you delayed Medicare enrollment because you had employer group health coverage (from an employer with 20+ employees), you get a Special Enrollment Period when that coverage ends:

  • Part B: You have 8 months after your employer coverage ends to enroll in Part B without penalty
  • Part D: You have 63 days after losing creditable drug coverage to enroll in a Part D plan without penalty
  • Medicare Advantage: You can join an MA plan during this period
  • Medigap: You may have guaranteed issue rights in certain circumstances
Critical Reminder About COBRA COBRA continuation coverage is not considered active employer coverage for Medicare purposes. If you are 65 or older and you elect COBRA instead of enrolling in Medicare, the late enrollment penalty clock starts ticking. You should enroll in Medicare first, then use COBRA (if needed) to supplement your coverage temporarily.

Moving SEP

If you move to a new area and your current Medicare Advantage or Part D plan is not available in your new location:

  • You have 2 months from the date of your move (starting the month after you move) to join a new plan in your area
  • You can switch MA plans, switch from MA to Original Medicare, or change Part D plans

Other Common SEPs

Qualifying Event SEP Duration What You Can Change
Losing employer group coverage 8 months (Part B); 63 days (Part D/MA) Enroll in Part B, join MA or Part D
Moving out of plan service area 2 months after move Switch MA or Part D plans
Losing Medicaid coverage 2 months after losing Medicaid Join MA or Part D plan
Entering or leaving a nursing home Ongoing while in/leaving facility Switch MA or Part D plans
Plan leaves your area or drops Medicare 2 months from notification Join a new plan
Qualifying for Extra Help (LIS) Once per quarter (ongoing) Switch Part D plans
Gaining or losing dual-eligible status Once per quarter Switch MA or Part D plans
Plan contract violation Varies (typically 2 months) Switch to another plan
Released from incarceration 2 months after release Enroll in Part B, join MA or Part D
Natural disaster or emergency CMS determines duration Varies based on CMS announcement

5-Star Plan SEP

If a Medicare Advantage or Part D plan in your area has received a 5-star quality rating from CMS, you can switch to that plan once per year at any time, regardless of enrollment periods. This SEP runs from December 8 through November 30 of the following year. You can check plan star ratings at Medicare.gov.

Medigap Open Enrollment Period

The Medigap Open Enrollment Period is separate from all other Medicare enrollment periods and is critically important for anyone considering a Medicare Supplement plan.

When: 6 Months Starting When Your Part B Is Effective

Your Medigap OEP begins the first day of the month your Medicare Part B coverage becomes effective and lasts for exactly 6 months. For most people turning 65, this starts the 1st of their 65th birthday month.

Why It Matters

During your Medigap OEP, you have guaranteed issue rights:

  • Insurance companies must sell you any Medigap plan they offer in North Carolina
  • They cannot deny you based on health conditions
  • They cannot charge you more because of pre-existing conditions
  • They cannot impose a waiting period for pre-existing conditions (if you had prior creditable coverage)

After your Medigap OEP closes, North Carolina Medigap insurers can use medical underwriting. This means they can:

  • Ask about your health history
  • Deny your application based on health conditions
  • Charge higher premiums based on your health status
This Is Your One Best Shot at Medigap North Carolina does not require Medigap insurers to offer guaranteed issue outside of the federal Medigap OEP (except in specific situations like losing employer coverage). If you think you might ever want a Medigap plan, your initial 6-month window is by far the best time to get one. Even if you start with Medicare Advantage, carefully consider whether you might want the option of Medigap in the future. For more on this critical decision, read Medicare Advantage vs. Original Medicare with Medigap.

Late Enrollment Penalties

If you miss your enrollment windows and do not have qualifying coverage, you may face permanent penalties that increase your premiums for life.

Part B Late Enrollment Penalty

For each full 12-month period you were eligible for Part B but not enrolled (and did not have creditable employer coverage), your Part B premium increases by 10%. This penalty is permanent.

Delay Penalty 2026 Monthly Premium (with penalty) Extra Cost Per Year
1 year late 10% $223.19 $243
2 years late 20% $243.48 $487
3 years late 30% $263.77 $730
5 years late 50% $304.35 $1,217

Part D Late Enrollment Penalty

For each full month you went without creditable prescription drug coverage after your initial enrollment window, your Part D premium increases by 1% of the national base beneficiary premium (approximately $0.35/month in 2026). This penalty is also permanent.

Example: If you go 30 months without creditable drug coverage, your Part D penalty would be approximately $10.41/month ($0.347 × 30), or about $125 extra per year, for life.

Part A Late Enrollment Penalty

Most people get Part A premium-free. However, if you do not qualify for premium-free Part A and you delay enrollment, your Part A premium increases by 10% for twice the number of years you were eligible but not enrolled.

To learn more about how these penalties add up, read our detailed analysis: 5 Medicare Mistakes That Could Cost You Thousands. For a full breakdown of current costs, see What Does Medicare Cost in 2026?

Frequently Asked Questions

The Annual Enrollment Period (AEP) runs from October 15 to December 7 each year and is when you can make changes to your Medicare Advantage or Part D plan for the following year. You can switch MA plans, switch from MA to Original Medicare, join or change Part D plans, or switch from Original Medicare to MA. The Medicare Advantage Open Enrollment Period (OEP) runs from January 1 to March 31 and is only for people already enrolled in a Medicare Advantage plan. During the OEP, you can switch to a different MA plan or switch from MA to Original Medicare (and join a Part D plan), but you cannot use it to join MA for the first time.
Part B late enrollment penalty: 10% of the standard premium for each full 12-month period you were eligible but not enrolled. This penalty is permanent and added to your premium for life. Part D late enrollment penalty: 1% of the national base beneficiary premium for each full month you went without creditable prescription drug coverage. This penalty is also permanent. For example, going without Part B for 2 years adds 20% to your premium permanently, and going without Part D for 24 months adds about $8.40/month permanently.
Common qualifying events for a Medicare Special Enrollment Period include: losing employer or union group health coverage, moving out of your plan's service area, losing Medicaid eligibility, entering or leaving a nursing home or skilled nursing facility, your plan leaving Medicare or stopping coverage in your area, qualifying for Extra Help (Low-Income Subsidy), and experiencing a plan contract violation. Each SEP has specific time limits, usually ranging from 2 to 8 months depending on the qualifying event.
Your Initial Enrollment Period (IEP) is a 7-month window centered around the month you turn 65. It begins 3 months before your 65th birthday month, includes your birthday month, and extends 3 months after your birthday month. For example, if your birthday is in June 2026, your IEP runs from March 2026 through September 2026. For the earliest coverage start date, you should enroll during the first 3 months of your IEP.

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