Medicare enrollment periods are specific windows during which you can enroll, change, or cancel your coverage. Acting outside these dates can mean going without adequate coverage for months or paying more than necessary.
Here is a complete guide to all Medicare enrollment periods for 2026, what you can do during each one, and how to prepare.
The most important date
The AEP (Oct 15 – Dec 7) is your best opportunity to change your Medicare plan each year. Changes made during this period take effect on January 1 of the following year. Don't miss it.
All Medicare Enrollment Periods
Annual Enrollment Period
The main period for Medicare changes. You can: enroll in Medicare Advantage, switch from one MA plan to another, return to Original Medicare, or change your drug plan (Part D). Changes take effect January 1.
Open Enrollment Period (Medicare Advantage)
If you already have a Medicare Advantage plan, you can switch to another MA plan or return to Original Medicare (with or without Part D). You cannot enroll in MA if you are on Original Medicare during this period. Only one change is allowed.
Initial Enrollment Period
Your first opportunity to enroll. Begins 3 months before your 65th birthday month and ends 3 months after. Not enrolling during this period can result in permanent late penalties on Part B and Part D premiums.
Special Enrollment Period
Triggered by qualifying life events: moving to a new area, losing employer coverage, becoming eligible for Medicaid, returning from international travel. You generally have 60 days from the event to make changes.
What Can You Do During AEP 2025 (for 2026)?
During the AEP from October 15 to December 7, 2025, you can:
- Enroll in a Medicare Advantage plan if you are on Original Medicare
- Switch from one Medicare Advantage plan to another
- Return to Original Medicare (with or without Part D)
- Enroll in, change, or cancel your Part D prescription drug plan
AEP Checklist: Get Ready in October
Review your Annual Notice of Change (ANOC). Each September, your current insurer sends a notice with all changes for the next year: premium, copays, doctor network, and drug formulary.
Verify your doctors are still in network. Networks change every year. Confirm your primary care doctor and favorite specialists will still accept your plan.
Review the drug formulary. Check that all your medications are still on the same tier and that copays have not increased significantly.
Compare with new available plans. New plans enter the market every year. What was the best option last year may not be today.
Consult a certified advisor. A certified agent can compare all plans available in your area and help you evaluate the total cost — not just the premium.
Late Enrollment Penalties
Part B Penalty
If you don't enroll in Part B when first eligible (and don't have other qualifying coverage such as employer insurance), you pay a penalty of 10% for every 12 months you didn't enroll. This penalty is permanent — you pay it for the rest of your life.
Part D (Prescription Drug) Penalty
If you go more than 63 days without qualifying prescription drug coverage, you pay a penalty of approximately 1% of the national base beneficiary premium for each month without coverage. This is also permanent.
What Happens If I Miss the AEP?
If you didn't make changes during the AEP, your current plan automatically renews for the next year. However, your plan's coverage, premium, and network may change, so it's important to review it even if you decide to stay with the same plan.
The only way to make changes outside the AEP is through the OEP (January–March, only for MA enrollees) or through a SEP if you have a qualifying life event.
Important reminder
At Lopcha we help you review your current plan vs. available alternatives for 2026. The service is completely free — our compensation is paid by the insurer, not you.
