The confusion comes from naming. The AEP you use to pick 2027 coverage ran October 15 through December 7, 2026. The 2027 window is for the following plan year.
Miss December 7 and your options narrow fast. This guide covers the calendar, what you can change, how to prepare, and what to do if the deadline slips by.
Key Takeaways
- AEP in 2027 runs October 15 to December 7, with coverage starting January 1, 2028.
- Compare costs, doctors, pharmacies, and drug formularies before you switch.
- Allowed changes depend on whether you have Original Medicare, Medicare Advantage, or standalone Part D.
- You don't have to change plans, but don't assume nothing else will change.
- Missing AEP doesn't guarantee another enrollment window.
Medicare AEP Dates for 2027 and Why the Deadline Matters
AEP is the yearly window when eligible beneficiaries can review or change Medicare Advantage and prescription drug coverage for the next plan year.
The 2027 AEP calendar
Federal regulations set the Medicare Advantage and Part D periods at October 15 through December 7 every year, with coverage starting the following January 1. The window follows that standing federal schedule each year; confirm the posted dates on Medicare.gov before you enroll.
| Enrollment season | AEP dates | Coverage starts |
|---|---|---|
| Fall 2026 (for plan year 2027) | Oct 15 – Dec 7, 2026 | Jan 1, 2027 |
| Fall 2027 (for plan year 2028) | Oct 15 – Dec 7, 2027 | Jan 1, 2028 |
The cutoff is firm. Medicare.gov says the plan must receive your request by December 7. It describes no general grace period afterward.
Why the deadline matters
Waiting until the last days leaves little time to read your plan's paperwork and compare options. Plans must deliver the Annual Notice of Change by September 30 and the Evidence of Coverage by October 15. Those documents show changes to premiums, deductibles, copays, networks, and formularies.
If you do nothing, your coverage generally continues automatically. But Medicare's yearly review guide notes that costs, benefits, and providers can change each year. Continuing is not the same as staying identical.
Many people skip the comparison. KFF found that 65% of beneficiaries did not compare coverage during the 2024 AEP. That is historical, not a 2027 forecast.
AEP compared with other enrollment periods
- Medicare Advantage Open Enrollment Period (MA OEP): January 1 to March 31 for people already in Medicare Advantage. One change allowed: another MA plan, or Original Medicare plus a standalone drug plan. Coverage starts the first of the next month.
- Initial Enrollment Period (IEP): For first-time enrollees. At 65, it spans seven months around your birthday month.
- Special Enrollment Periods (SEPs): Triggered by events such as moving out of your plan's service area, losing creditable drug coverage, or a plan leaving Medicare.
Best Time to Make a Medicare Plan Change During AEP
There is no single best day. Timing depends on your current coverage, health needs, and how long you need to verify details.
Medicare's own guidance suggests reviewing notices starting October 1, but names no ideal date inside AEP. Enrolling early doesn't start coverage early; AEP elections begin January 1 regardless.
If you have Original Medicare
You can join a Medicare Advantage plan, join or switch a standalone Part D plan, or change nothing.
- You still owe the Part B premium after joining Medicare Advantage, even with a $0-premium plan.
- Going 63 or more consecutive days without creditable drug coverage can trigger a Part D late-enrollment penalty.
- The penalty is 1% of the national base beneficiary premium for each full uncovered month. The base premium is $38.99 for 2026 and $41.33 for 2027.
If you have Medicare Advantage
You can switch to another MA plan, return to Original Medicare, add separate drug coverage when appropriate, or keep your plan.
Compare the exact plan, not the insurer's brand. Check:
- Network and service area
- Drug coverage and cost-sharing
- Extra benefits
If you return to Original Medicare, a Medigap insurer may use medical underwriting, so coverage isn't guaranteed. State law may add protections.
If you have standalone Part D
You can switch drug plans, move into a Medicare Advantage plan, drop Part D, or keep what you have.
Dropping creditable coverage and rejoining later can mean a penalty, so verify the rules at Medicare.gov first. People who get Extra Help generally don't pay it.
If you're newly eligible or had a life event
AEP isn't the standard route for first-time enrollment. Check your Initial Enrollment Period or a possible SEP before applying. The effective date and options vary by circumstance.
Signs You're Ready and Best Practices for AEP 2027
You're ready when you can explain what is changing, why the plan fits your needs, and how you'll submit before the deadline.
When it's time to review coverage
Read your Annual Notice of Change and Evidence of Coverage. Look for changes in:
- Premiums, deductibles, and copays
- Networks and pharmacy arrangements
- Formularies and prior authorization rules
- Supplemental benefits and plan availability
Then list your own needs:
- Doctors, specialists, and hospitals
- Pharmacies, medications, and dosages
- Expected procedures
- Travel or moves
- Dental, vision, or hearing care
A practical comparison process
Compare total expected spending, not just the monthly premium. Factor in:
- Medical cost-sharing
- Drug costs
- Out-of-network exposure
- The plan's maximum out-of-pocket limit
For reference, CMS's 2026 in-network ceiling is $9,250 for most MA plan types. Plans may set lower limits, and 2028 figures will differ.
Use Medicare's Plan Finder at Medicare.gov/plan-compare. Check each medication against the plan's current formulary. Confirm that each key provider, hospital, and pharmacy participates in that exact plan. Preferred pharmacies may lower drug costs.
Submit and document your election
- Start early, in October.
- Submit before December 7.
- Save your confirmation or reference number.
- Call the plan or Medicare if your status is unclear.
Don't cancel existing coverage based only on an application attempt. When you switch drug plans, the old coverage ends when the new one begins, so you don't cancel separately. Verify how disenrollment works for your specific change.
When professional guidance may help
Muneris Benefits, an independent agency serving Virginia and West Virginia since 1990, has licensed agents who help Medicare beneficiaries compare coverage, understand plan details, and handle transitions. Plan availability, benefits, networks, and eligibility vary by service area and circumstance, so confirm options through Medicare.gov, the plan, or a licensed agent.
When to Avoid Waiting and What Happens If AEP Is Missed
Delay hurts most if you take several prescriptions, rely on specific providers, or have application questions that need time to resolve.
Act right away if:
- You receive your Annual Notice of Change and see higher costs
- A medication or provider drops out of coverage
- Your plan is leaving your service area
- Your benefits no longer match your health needs
If you miss AEP, you may have to keep your current coverage until another period opens. Existing MA members may still use the MA OEP, and qualifying events can create an SEP.
Eligibility isn't guaranteed, so confirm with Medicare.gov, 1-800-MEDICARE, or your plan. MA OEP doesn't help people in Original Medicare with standalone Part D.
Watch for scams. Plans generally can't cold-call, text, or knock on doors to sell Medicare Advantage or Part D. Exceptions include prior consent, outreach you started, and contact from your current plan. Agents must be state-licensed.
Never share your Medicare Number with an unsolicited caller, and confirm deadlines in official plan materials or at 1-800-MEDICARE (1-800-633-4227).
Conclusion
The AEP held in 2027 runs October 15 through December 7, 2027, with coverage generally starting January 1, 2028. Enrollment for 2027 coverage took place during the 2026 AEP.
No single best enrollment date fits everyone. Your timing depends on your coverage needs, eligibility, doctors, medications, and costs. Submit an informed election before December 7.
Frequently Asked Questions
What is the AEP period?
Medicare's Annual Enrollment Period lets beneficiaries change Medicare Advantage and Part D coverage. The 2027 AEP window runs October 15 to December 7, with coverage generally starting January 1, 2028. The separate window for plan-year 2027 coverage ran in fall 2026.
What is AEP vs OEP?
AEP is the fall period open to eligible beneficiaries for broad changes. The MA OEP runs January 1 to March 31 for people already in Medicare Advantage, allowing one switch to another MA plan or to Original Medicare.
When should I enroll in a Medicare Advantage plan?
It depends on your situation: first enrollment, an AEP change, or a Special Enrollment Period. Current MA members may also have the MA OEP. Confirm which period applies before applying.
How long does it take to get approved for a Medicare Advantage plan?
AEP requests received by December 7 generally take effect January 1. CMS requires a plan notice within 10 calendar days after the plan receives CMS's transaction response, not after you apply. Apply early and confirm status with the plan.
Do I have to re-enroll in my Medicare Advantage plan every year?
Not if the plan continues; coverage renews automatically. Still, read your Annual Notice of Change and act if costs, benefits, networks, or your needs have changed.
Can you go back to Original Medicare during open enrollment?
Yes. AEP generally lets Medicare Advantage enrollees return to Original Medicare and add a standalone drug plan. Eligible current MA members may also switch during the MA OEP. Weigh Part D and Medigap implications first.
