Medicare’s annual open enrollment runs October 15 through December 7, 2026, and the decisions you make then take effect January 1, 2027. The six weeks before it opens are the best time to gather your documents, read the plan-change notice that arrives by September 30, and decide whether your current coverage still fits, so you are comparing plans rather than scrambling when the window opens.
🔍 When is my Medicare enrollment window?
Enter the month you turn (or turned) 65 to see your personal 7-month Initial Enrollment Period and how the Oct 15 – Dec 7 window applies to you.
Month and year of your 65th birthday:
General information, not enrollment advice; confirm at Medicare.gov or 1-800-MEDICARE.
Key Takeaways
Enrollment window: October 15 to December 7; changes start January 1, 2027
Watch the mail: your Annual Notice of Change (ANOC) must arrive by September 30 and lists every 2027 change to your plan
You can switch Medicare Advantage plans, move between Original Medicare and Advantage, or change Part D drug plans
Free, unbiased help is available through your State Health Insurance Assistance Program (SHIP)
Doing nothing keeps your current plan, including any premium, copay, or network changes it has made
What you can change during open enrollment
Change
Allowed Oct 15 – Dec 7?
Switch from one Medicare Advantage plan to another
Yes
Leave Medicare Advantage for Original Medicare (plus a Part D plan)
Yes
Join Medicare Advantage from Original Medicare
Yes
Change or drop a Part D prescription drug plan
Yes
Buy or switch a Medigap (supplement) policy
Not guaranteed; medical underwriting may apply outside protected windows
Medigap is the piece most people misunderstand. Open enrollment does not give you a guaranteed right to buy a supplement policy; that right generally exists only in the six months after you first enroll in Part B and in a handful of special situations. If your plan is to leave Medicare Advantage for Original Medicare with a Medigap policy, confirm in September that an insurer will accept you before you make the switch.
The six-week checklist
Week 1 (late August): gather your records
List every prescription with dosage and how often you fill it. This list drives the Part D comparison and is the single biggest source of savings.
List your doctors, hospitals, and pharmacies, including any specialist you expect to need next year.
Pull this year’s costs. Add up premiums, deductibles, copays, and drug costs from January through August to get a real baseline.
Create or log in to your Medicare.gov account. The Plan Finder can save your drug list and pharmacies so the comparison takes minutes instead of hours.
Week 2 (early September): understand your current plan’s 2027 changes
Watch for the ANOC. Every Medicare Advantage and Part D plan must mail it by September 30. It shows next year’s premium, deductible, copays, drug tier changes, and provider network changes side by side with this year’s.
Check the drug formulary specifically. A drug moving from tier 2 to tier 4, or being dropped entirely, can cost far more than a premium increase.
Confirm your doctors are still in network for 2027, not just 2026. Networks change every year.
Week 3 (mid-September): decide whether you need to shop
If your ANOC shows no meaningful changes, your doctors are still covered, your drugs are still on the formulary at the same tier, and your total cost this year was manageable, staying put is a legitimate choice. If any of those changed, or your health needs changed, plan to compare. People who compare Part D plans each year often find a cheaper option because drug pricing between plans shifts significantly from year to year.
Week 4 (late September): line up help
Book a SHIP appointment. State Health Insurance Assistance Programs offer free, one-on-one counseling from trained volunteers who do not sell insurance. Slots fill quickly in October, so booking in September matters.
Note the 2027 Part B premium and deductible when the government announces them, typically in the fall. They are deducted from Social Security checks and affect your net benefit.
Understand the Part D out-of-pocket cap. Since 2025 there has been an annual cap on what you pay for covered drugs, adjusted each year; the 2027 figure will appear in plan materials. Plans also offer a payment option that spreads costs across the year.
Week 5 (early October): preview plans
Plan details for the coming year are posted on Medicare.gov on October 1, two weeks before enrollment opens. Use that window to run the Plan Finder with your saved drug and pharmacy list, sort by estimated total annual cost rather than premium alone, and read the star ratings. A plan with a $0 premium and a restrictive network or high drug costs can be far more expensive than one with a modest premium.
Week 6 (mid-October): enroll
Once you have chosen, enroll online through Medicare.gov, by calling 1-800-MEDICARE, or directly with the plan. Enrolling in a new plan automatically disenrolls you from the old one, so do not cancel anything separately. Keep the confirmation number. If you change your mind, you can enroll again before December 7; the last enrollment received is the one that takes effect.
Common mistakes to avoid
Comparing on premium only. Total annual cost, including drugs and expected visits, is the number that matters.
Assuming your plan did not change. Even the same plan name can carry new copays and a smaller network in 2027.
Ignoring the mail. The ANOC is easy to mistake for marketing and discard.
Responding to sales calls. Medicare will not call you to sell a plan; unsolicited calls are a common source of enrollment errors and scams.
Missing the Medigap underwriting issue when leaving Medicare Advantage.
If you miss the window
Medicare Advantage members get a second chance from January 1 to March 31, when they can switch to another Advantage plan or return to Original Medicare with a Part D plan, but cannot move from Original Medicare into Advantage. Special enrollment periods also exist for moves, loss of other coverage, and plan terminations. Outside those, you are generally locked in until the next October.
FAQ
Does open enrollment apply if I have Original Medicare and no drug plan?
Yes. You can add a Part D plan during the window, though a late enrollment penalty may apply if you went without creditable drug coverage for more than 63 days after becoming eligible.
Is this the same as ACA marketplace open enrollment?
No. The ACA marketplace window opens November 1 and covers people under 65 without Medicare. The dates overlap, which causes confusion, but the programs are separate.
Can I keep my Medigap policy if I switch Part D plans?
Yes. Medigap and Part D are separate; changing a drug plan does not affect a supplement policy.
When will 2027 premiums be published?
Plan-level premiums appear on Medicare.gov on October 1. The standard Part B premium and deductible are announced by the federal government in the fall, usually before enrollment opens or shortly after.
A one-page summary to print
Late August: drug list, provider list, this year’s costs, Medicare.gov account. September: read the ANOC, check the formulary and network, book SHIP. October 1: preview 2027 plans and sort by total cost. October 15 to December 7: enroll and keep the confirmation. January 1: new coverage begins, so refill prescriptions and confirm appointments under the new plan in the first week.
Sources
Medicare.gov, Joining a health or drug plan and enrollment periods
Centers for Medicare & Medicaid Services, Annual Notice of Change requirements
State Health Insurance Assistance Program (shiphelp.org)
This is general information, not personalized insurance advice. Last updated August 26, 2026 · InfoBrief Staff
