Medicare Enrollment Periods 2025: Complete Guide to When & How to Enroll
Understanding Medicare enrollment periods is critical for avoiding penalties, getting the coverage you need, and maximizing your benefits. Whether you're turning 65, changing plans, or experiencing a life change, knowing which enrollment period applies to you can save you thousands of dollars and ensure continuous coverage.
Critical Medicare Enrollment Dates for 2025
Jump to Section
📅 Enrollment Timeline
No enrollment periods currently available for your situation.
Annual Enrollment Period (AEP): October 15 - December 7
The Annual Enrollment Period, also called Medicare Open Enrollment, is the main period when anyone with Medicare can make changes to their Medicare Advantage or Part D prescription drug coverage. This is your annual opportunity to review and switch plans.
What You Can Do During AEP:
- ✓Join a Medicare Advantage plan for the first time if you have Original Medicare
- ✓Switch Medicare Advantage plans from one MA plan to another
- ✓Drop Medicare Advantage and return to Original Medicare
- ✓Enroll in a Part D plan, switch Part D plans, or drop Part D coverage
- ✓Switch from Medicare Advantage with Part D to separate Medicare Advantage and Part D plans
AEP Quick Facts
Important AEP Limitations:
- Cannot change Medicare Supplement (Medigap) plans without medical underwriting during AEP
- Cannot enroll in Medicare Parts A or B during AEP (use General Enrollment Period)
- Changes submitted late in the period may be delayed - enroll early to avoid issues
- If you make multiple changes, only your last submitted enrollment counts
Medicare Advantage Open Enrollment Period: January 1 - March 31
The Medicare Advantage Open Enrollment Period (MA-OEP) is specifically for people already enrolled in a Medicare Advantage plan. During this period, you can make one change to your coverage.
What You Can Do During MA-OEP:
- •Switch from your current Medicare Advantage plan to a different Medicare Advantage plan
- •Drop your Medicare Advantage plan and return to Original Medicare
- •If you drop MA and return to Original Medicare, you can also join a Part D plan
What You CANNOT Do:
- Cannot join Medicare Advantage for the first time (must use AEP or IEP)
- Cannot make multiple changes - only one change allowed
- Cannot switch Part D plans unless dropping MA and enrolling in standalone Part D
MA-OEP Timeline
Who Should Use MA-OEP?
- →You're unhappy with your current Medicare Advantage plan
- →Your doctors left your plan's network
- →You want to switch back to Original Medicare
- →You found a better Medicare Advantage plan after AEP ended
Initial Enrollment Period (IEP): Your First Medicare Enrollment Window
Your Initial Enrollment Period is a 7-month window when you first become eligible for Medicare. For most people, this is around your 65th birthday. This is the most important enrollment period because it offers guaranteed issue rights for Medicare Supplement and avoids late enrollment penalties.
IEP 7-Month Timeline
What You Can Enroll In During IEP:
- Medicare Part A (hospital insurance) - usually automatic if receiving Social Security
- Medicare Part B (medical insurance) - must actively enroll
- Medicare Advantage plan (replaces Original Medicare)
- Medicare Supplement (Medigap) with guaranteed issue rights
- Part D prescription drug plan
IEP Example Timeline
Critical IEP Warnings:
- ⚠️Missing IEP can cost you - late enrollment penalties for Part B and Part D last your entire lifetime
- ⚠️Employer coverage matters - if you have creditable employer coverage, you can delay enrollment without penalty
- ⚠️Medicare Supplement guaranteed issue - your 6-month Medigap Open Enrollment starts when Part B begins
IEP Strategy Tips:
- Enroll in the 3 months BEFORE your birthday for coverage to start on your birthday
- Start researching plans 4-5 months before turning 65
- If choosing Medigap, enroll during IEP for guaranteed issue rights
- Compare Medicare Advantage vs. Original Medicare + Medigap
- Work with a licensed agent (no cost to you) for personalized guidance
Special Enrollment Periods (SEP): Enrollment Rights for Qualifying Life Events
Special Enrollment Periods allow you to enroll in or change Medicare coverage outside of regular enrollment periods when you experience certain qualifying life events. SEPs provide critical protections and enrollment rights when circumstances change.
Moving to New Area
Trigger: Permanently move outside your plan's service area
Window: 2 months before move through 2 months after
Changes Allowed: Join, switch, or drop Medicare Advantage or Part D
Losing Employer Coverage
Trigger: Lose employer/union health coverage (including COBRA)
Window: 2 months before through 2 months after coverage ends
Changes Allowed: Enroll in any Medicare plan, including Medigap with guaranteed issue
Qualify for Extra Help
Trigger: Qualify for Medicare Savings Program or Extra Help with prescription costs
Window: Once per quarter when eligible
Changes Allowed: Switch Medicare Advantage or Part D plans
Plan Leaves Your Area
Trigger: Your Medicare Advantage plan stops offering coverage in your county
Window: From notice through 2 months after coverage ends
Changes Allowed: Join another MA plan, return to Original Medicare, or enroll in Medigap (guaranteed issue)
Nursing Home/Institution
Trigger: Enter, live in, or leave a skilled nursing facility or long-term care hospital
Window: Once per calendar quarter
Changes Allowed: Switch Medicare Advantage or Part D plans
Medicare Involuntary Disenrollment
Trigger: Medicare terminates plan contract or plan goes bankrupt
Window: 2 months before through 2 months after disenrollment
Changes Allowed: Enroll in any Medicare plan
Disaster Emergency
Trigger: Federal or state disaster declaration (hurricane, wildfire, etc.)
Window: During emergency period and 2 months after
Changes Allowed: Switch Medicare Advantage or Part D plans in affected areas
Medicaid Status Change
Trigger: Gain or lose Medicaid eligibility (dual-eligible status change)
Window: Month you gain/lose Medicaid plus following 2 months
Changes Allowed: Switch to different Medicare Advantage or Part D plan
Plan Material Misrepresentation
Trigger: Insurance company misrepresented plan or violated contract terms
Window: Varies by situation - determined case-by-case
Changes Allowed: Switch plans or return to Original Medicare
How to Use a Special Enrollment Period
- Verify Qualifying Event: Ensure your situation qualifies for an SEP
- Gather Documentation: Collect proof of qualifying event (termination letter, move confirmation, etc.)
- Act Within Time Limit: Most SEPs have 63-day windows - don't delay
- Submit Enrollment: Apply for new coverage through plan, agent, or Medicare.gov
- Provide Proof: Submit documentation proving qualifying event when requested
SEP Important Notes:
- Most SEPs allow changes only to plans in your current geographic area
- You typically cannot use SEPs to change Medicare Supplement plans (except specific guaranteed issue situations)
- Some SEPs are limited to certain types of plans (e.g., 5-star plans have their own SEP from Dec 8-Nov 30)
- Documentation requirements vary by qualifying event - work with an agent to ensure proper paperwork
Medicare Supplement (Medigap) Open Enrollment Period
Unlike Medicare Advantage, Medicare Supplement (Medigap) has a one-time, 6-month Open Enrollment Period that starts when you turn 65 AND enroll in Medicare Part B. This is the most important enrollment period for Medigap because you have guaranteed issue rights - insurance companies cannot deny you coverage or charge you more due to health conditions.
Medigap Open Enrollment Benefits
- ✓Guaranteed Issue: Cannot be denied coverage regardless of health
- ✓No Medical Underwriting: No health questions or exams required
- ✓Standard Pricing: Cannot charge more due to pre-existing conditions
- ✓No Waiting Periods: Pre-existing conditions covered immediately
- ✓Full Plan Choice: Access to all Medigap plans available in your state
After Open Enrollment Ends:
Once your 6-month Medigap Open Enrollment Period ends, you can still apply for Medicare Supplement coverage, but insurance companies can use medical underwriting to evaluate your health. This may result in:
- Higher premiums (10-50% above standard rates)
- Coverage denials for serious health conditions
- Exclusions for pre-existing conditions
- Waiting periods for certain benefits
Medigap Open Enrollment Timeline
Delayed Part B Enrollment
If you delay Part B enrollment past 65 due to employer coverage, your Medigap Open Enrollment Period starts when you actually enroll in Part B, not when you turn 65. For example, if you enroll in Part B at age 68, your 6-month Medigap OEP begins at age 68.
Medicare Enrollment Periods Comparison Chart
| Enrollment Period | Dates | Who Can Use It | What You Can Change |
|---|---|---|---|
| Annual Enrollment Period (AEP) | Oct 15 - Dec 7 (annual) | Anyone with Medicare Parts A & B | Join/switch/drop Medicare Advantage or Part D |
| Medicare Advantage Open Enrollment | Jan 1 - Mar 31 (annual) | People already in Medicare Advantage | Switch MA plans or drop MA (one change only) |
| Initial Enrollment Period (IEP) | 7 months around 65th birthday | New Medicare beneficiaries turning 65 | Enroll in all Medicare coverage (A, B, MA, Part D, Medigap) |
| Special Enrollment Periods (SEP) | Varies by qualifying event | Those with qualifying life events | Depends on event - typically MA or Part D changes |
| Medigap Open Enrollment | 6 months starting when Part B begins | New Medicare Part B enrollees | Enroll in any Medigap plan with guaranteed issue |
| General Enrollment Period | Jan 1 - Mar 31 (annual) | Those who missed IEP | Enroll in Part A or Part B (penalties may apply) |
Frequently Asked Questions About Medicare Enrollment Periods
What is Medicare Annual Enrollment Period (AEP)?
Medicare Annual Enrollment Period (AEP) runs from October 15 through December 7 every year. During AEP, anyone with Medicare can enroll in, switch, or drop a Medicare Advantage plan or Part D prescription drug plan. Changes made during AEP take effect January 1st of the following year. This is the most important enrollment period for Medicare Advantage and Part D plans.
When is Medicare Open Enrollment?
There are multiple Medicare Open Enrollment periods: 1) Annual Enrollment Period (AEP) for Medicare Advantage and Part D runs October 15 - December 7 annually. 2) Medicare Advantage Open Enrollment Period (OEP) runs January 1 - March 31 for those already in Medicare Advantage plans to make one change. 3) Medicare Supplement Open Enrollment is a one-time 6-month period starting when you turn 65 and enroll in Part B.
What is the Initial Enrollment Period for Medicare?
The Initial Enrollment Period (IEP) is a 7-month window when you first become eligible for Medicare, typically around your 65th birthday. It includes the 3 months before your birthday month, your birthday month, and 3 months after. During IEP, you can enroll in Medicare Part A, Part B, Medicare Advantage, Part D, and Medicare Supplement without penalties. This is a one-time enrollment period with guaranteed issue rights for Medigap.
What are Special Enrollment Periods for Medicare?
Special Enrollment Periods (SEP) allow you to enroll in or change Medicare coverage outside regular enrollment periods due to qualifying life events. Common SEPs include: moving to a new service area, losing employer coverage, qualifying for Extra Help, Medicare Advantage plan leaving your area, entering or leaving a nursing home, or gaining/losing Medicaid. Most SEPs provide a 63-day window to make changes after the qualifying event.
Can I enroll in Medicare outside of enrollment periods?
You can enroll in Medicare Part A and Part B during General Enrollment Period (January 1 - March 31) if you missed your Initial Enrollment Period, but coverage may not start until July 1 and you may face late enrollment penalties. For Medicare Advantage and Part D, you need to wait for Annual Enrollment Period (Oct 15-Dec 7) or qualify for a Special Enrollment Period. Medicare Supplement can be purchased year-round but may require medical underwriting outside Open Enrollment.
What happens if I miss Medicare enrollment deadlines?
Missing Medicare enrollment deadlines can result in: 1) Late enrollment penalties for Part B (10% per year) and Part D (1% per month without creditable coverage) that last your lifetime, 2) Gaps in coverage leaving you responsible for all medical costs, 3) Delayed coverage start dates (may have to wait months), 4) Loss of guaranteed issue rights for Medicare Supplement requiring medical underwriting. If you have employer coverage or a qualifying event, you may qualify for a Special Enrollment Period to avoid penalties.
How do I know which Medicare enrollment period applies to me?
Your applicable enrollment period depends on your situation: Initial Enrollment Period if you are turning 65 or newly eligible for Medicare due to disability; Annual Enrollment Period (Oct 15-Dec 7) to change Medicare Advantage or Part D plans; Medicare Advantage Open Enrollment (Jan 1-Mar 31) if already in MA; Special Enrollment Period if you have a qualifying life event like moving or losing coverage; Medicare Supplement Open Enrollment if you are newly enrolled in Part B. Contact a licensed Medicare agent for personalized guidance.
Can I change my Medicare coverage during Annual Enrollment?
Yes, during Annual Enrollment Period (October 15 - December 7), you can: switch from Original Medicare to Medicare Advantage or vice versa, join, switch, or drop a Medicare Advantage plan, join, switch, or drop a Part D prescription drug plan, or switch from one Medicare Advantage plan with drug coverage to another. You cannot change Medicare Supplement plans without underwriting (except in certain states), as AEP does not apply to Medigap. All changes take effect January 1.
Get Expert Help with Medicare Enrollment
Navigating Medicare enrollment periods can be confusing. Our licensed Medicare specialists will help you understand which enrollment period applies to you, when to enroll, and which coverage options best meet your needs. Expert guidance at no cost to you.
Licensed in all 50 states • No-cost consultations • Independent advice from experienced Medicare specialists
Medicare Enrollment by Location
Medicare enrollment periods are the same nationwide, but plan availability and benefits vary by location. Explore Medicare options specific to your area:
Popular Medicare Advantage Locations
Related Medicare Resources
Medicare Supplement Enrollment
Complete guide to Medigap enrollment periods, guaranteed issue rights, and enrollment process.
Read enrollment guide →Medicare Advantage Plans
Compare Medicare Advantage plans with Part D, extra benefits, and low premiums.
Explore MA plans →Medicare Supplement Plan G
Most popular Medigap plan with comprehensive coverage and predictable costs.
Learn about Plan G →