Medicare annual enrollment period runs from October 15 to December 7 every year. This is the one window when every Medicare beneficiary can change their coverage. You can switch Medicare Advantage plans. You can return to Original Medicare. You can join, change, or drop a Part D prescription drug plan.
Any changes you make take effect January 1 of the following year. For 2026, the medicare annual enrollment period opens on October 15, 2026. All changes made during this window become active on January 1, 2027. Missing this deadline can mean paying higher premiums for years. It can also mean being stuck in a plan that no longer fits your needs. Understanding how the medicare annual enrollment period works puts you in control of your healthcare costs.
When Is the Medicare Annual Enrollment Period?
The medicare annual enrollment period for 2026 begins on October 15, 2026 and ends on December 7, 2026. That gives you 54 days to review your options. Mark your calendar now so you do not miss it. Changes made during this window take effect on January 1, 2027.
| Enrollment Period | Start Date | End Date | Changes Effective |
|---|---|---|---|
| Annual Enrollment Period (AEP) | October 15, 2026 | December 7, 2026 | January 1, 2027 |
| Medicare Advantage Open Enrollment | January 1, 2027 | March 31, 2027 | First of month after enrollment |
| General Enrollment Period | January 1, 2026 | March 31, 2026 | July 1, 2026 |
| Initial Enrollment Period | 3 months before turning 65 | 3 months after turning 65 | Varies by sign-up month |
After the AEP closes on December 7, a separate window opens. The Medicare Advantage Open Enrollment Period runs from January 1 to March 31, 2027. During that time, you can switch between Medicare Advantage plans. You can also drop Medicare Advantage and return to Original Medicare. However, you cannot use that period to join a Part D plan on its own.
Who Is Eligible During This Period?
Anyone currently enrolled in Medicare can make changes during the medicare annual enrollment period. This includes people on Original Medicare (Parts A and B). It also includes those enrolled in Medicare Advantage or Part D plans. You do not need a qualifying life event. The AEP is an open window for all beneficiaries.
Most Medicare beneficiaries are 65 or older. However, people under 65 who receive Social Security Disability Insurance for 24 months also qualify. Those diagnosed with ALS qualify immediately with no waiting period. You must be a U.S. citizen or legal permanent resident to participate.
If you are new to Medicare, your Initial Enrollment Period takes priority. That seven-month window starts three months before your 65th birthday month. The medicare annual enrollment period is mainly for people who already have coverage and want to adjust it.
What Can You Do During the Medicare Annual Enrollment Period?
The medicare annual enrollment period gives you several options. You can switch from one Medicare Advantage plan to another. You can leave Medicare Advantage and return to Original Medicare. You can move from Original Medicare to a Medicare Advantage plan. If you have Original Medicare, you can join, switch, or drop a Part D drug plan.
This is a good time to review your plan’s formulary. Drug coverage changes every year. A medication covered this year might cost more next year. For 2026, the Part B monthly premium is $202.90. The Part B annual deductible is $283. The Part A inpatient hospital deductible is $1,736. These costs may affect which plan works best for you.
There is good news for 2026. Insulin is now covered with no cost-sharing under Part D. Adult vaccines recommended by the Advisory Committee on Immunization Practices are covered at no cost. The Medicare Prescription Payment Plan lets you spread drug costs across the year. Average Medicare Advantage premiums have dropped to around $14 per month.
What Happens If You Miss This Deadline?
Missing the medicare annual enrollment period has real consequences. If you go without Part D drug coverage when you were eligible, you face a late enrollment penalty. The penalty is 1% of the national base beneficiary premium for each full month you lacked coverage. In 2026, the base premium is $38.99. Twelve months without coverage adds roughly $4.68 per month to your premium. This penalty lasts for as long as you have Part D coverage.
Part B late enrollment penalties are even steeper. Your premium increases by 10% for each full 12-month period you could have had Part B but did not sign up. Two years of delay means a 20% surcharge. This penalty is permanent. It stays on your monthly bill for the rest of your time on Medicare.
If you miss the AEP, your next chance to make changes is limited. The Medicare Advantage Open Enrollment Period (January 1 through March 31) only allows certain switches. Otherwise, you must wait for the next medicare annual enrollment period. Special Enrollment Periods exist for qualifying life events like moving or losing employer coverage. But those have strict eligibility rules.
Step-by-Step: How to Enroll
Start by reviewing your current coverage in September. Medicare plans mail an Annual Notice of Change each fall. This document lists every change to your plan for the coming year. Read it carefully. Compare your current medications against the updated formulary. Check whether your doctors remain in-network.
Next, use the Medicare Plan Finder tool at Medicare.gov to compare options. Enter your ZIP code, medications, and preferred pharmacies. The tool shows estimated annual costs for each plan. You can also call 1-800-MEDICARE (1-800-633-4227) for help. TTY users can reach them at 1-877-486-2048. Both lines are available 24 hours a day, 7 days a week.
Once you choose a plan, enroll online at Medicare.gov or call the plan directly. Have your Medicare card ready. You will need your Medicare Beneficiary Identifier number. Keep your confirmation number or letter as proof of enrollment. Your new coverage begins January 1, 2027. You do not need to cancel your old plan. Enrollment in the new plan automatically ends your previous coverage.
Common Mistakes to Avoid
The biggest mistake is doing nothing. Many people assume their plan stays the same. Plans change formularies, networks, and costs every year. A plan that worked last year may cost you hundreds more next year. Always review your options during the medicare annual enrollment period.
Another common error is focusing only on monthly premiums. A low-premium plan may have high deductibles or copays. Look at total out-of-pocket costs instead. Factor in your prescriptions, doctor visits, and any planned procedures. The cheapest premium is not always the cheapest plan.
Do not wait until the last day. Enrolling on December 7 leaves no room for problems. Website outages, long hold times, and paperwork errors happen. Start comparing plans in mid-October. Submit your enrollment by late November. Also, do not confuse the medicare annual enrollment period with other enrollment windows. The AEP is specifically October 15 through December 7. Enrolling at the wrong time may not give you the changes you need.
Frequently Asked Questions
Can I change my Medicare Supplement (Medigap) plan during the annual enrollment period?
No. The medicare annual enrollment period does not apply to Medigap policies. Medigap plans have their own enrollment rules. Your best opportunity to buy Medigap is during your six-month Medigap Open Enrollment Period, which starts when you turn 65 and enroll in Part B.
What if I have coverage through my employer?
If you have employer-sponsored coverage, you may not need to make changes during the AEP. Employer plans often coordinate with Medicare. Talk to your benefits administrator before making any switches. Dropping employer coverage to join a Medicare plan could affect your spouse or dependents.
Will my doctors accept my new plan?
That depends on the plan you choose. Medicare Advantage plans use provider networks. Before enrolling, check the plan’s provider directory. Original Medicare is accepted by any provider who takes Medicare assignment. Roughly 97% of non-pediatric physicians accept Medicare.
How do I know if my prescriptions are covered under a new plan?
Every Part D and Medicare Advantage plan with drug coverage publishes a formulary. This is the list of covered medications with their cost tiers. Use the Medicare Plan Finder to enter your drugs and see which plans cover them. Formularies change annually, so check every year during the medicare annual enrollment period.
Compare Medicare Plans
Ready to explore your Medicare options? Use the official Medicare Plan Finder or contact your local SHIP counselor for free, unbiased help.
Official Sources & Resources
For verified Medicare information and enrollment help:
- Medicare.gov: medicare.gov
- CMS.gov: cms.gov
- NAIC Medigap Guide: naic.org
- KFF Medicare Research: kff.org/medicare
- Find Your SHIP: medicare.gov/contacts
Content last reviewed April 2026. If you notice any outdated information, please contact us.