Medicare Annual Enrollment Period: Oct 15 to Dec 7, and What to Check
The one window each year when anyone on Medicare can change coverage without a special reason.
By naveen · Updated · How we research our guides
What to know
- The Medicare Annual Enrollment Period runs October 15 to December 7 every year, and changes made in it take effect January 1.
- In it, your parent can switch between Original Medicare and Medicare Advantage, change plans, and join or drop drug coverage.
- Plans can change their costs, coverage and networks each year, so a review is worth doing even when nothing seems wrong.
- A separate window from January 1 to March 31 is narrower and only for people already in Medicare Advantage.
- Retirement Checklist puts the annual Medicare review in order with the rest of your parent's plan.
The Medicare Annual Enrollment Period runs October 15 to December 7 every year; for 2027 coverage, that's October 15 to December 7, 2026. Changes made in it take effect on January 1.
CMS describes it as the time when "all people with Medicare can change their Medicare health plans and prescription drug coverage for the following year to better meet their needs." Medicare.gov calls it the Open Enrollment Period.
What can you change during Open Enrollment?
Your parent's health plan, drug plan, or both. According to Medicare.gov, during Open Enrollment you can:
- Join, drop, or switch to another Medicare Advantage plan, with or without drug coverage
- Switch from Original Medicare to Medicare Advantage, or from Medicare Advantage to Original Medicare
- Join, drop, or switch to another Medicare drug plan if you're in Original Medicare
Coverage from those changes starts on "January 1 of the next year (the plan must get your request to join by December 7)."
What are the different Medicare enrollment periods?
There are four main periods, plus Special Enrollment Periods. All dates are from Medicare.gov:
| Period | When | Who it's for |
|---|---|---|
| Initial Enrollment | 7 months: from 3 months before the month someone turns 65 to 3 months after | Signing up for Medicare for the first time |
| General Enrollment | January 1 to March 31, each year | Signing up for Part B (and premium Part A) after missing the Initial Enrollment Period |
| Open Enrollment | October 15 to December 7, each year | Anyone on Medicare changing their health or drug plan |
| Medicare Advantage Open Enrollment | January 1 to March 31, each year | Only people already in a Medicare Advantage plan |
Special Enrollment Periods apply "Only for certain situations that happen in your life, like moving to a new address, losing or changing your current coverage," in Medicare.gov's words. Which ones apply depends on the event, so it can help to look them up when something changes.
Is the January window a second chance?
Only for people already in Medicare Advantage. The Medicare Advantage Open Enrollment Period (January 1 to March 31) lets them switch to another Medicare Advantage plan, or "Drop your Medicare Advantage Plan and return to Original Medicare. You'll also be able to join a separate Medicare drug plan." Someone on Original Medicare who misses the autumn window can't use it.
How do Medicare Advantage and Original Medicare differ?
In networks, referrals, Medigap and out-of-pocket limits. We won't tell you which is right (that depends on your parent's doctors, health and budget), but here is how Medicare.gov describes the differences:
| Original Medicare | Medicare Advantage | |
|---|---|---|
| Doctors & hospitals | Any doctor or hospital that takes Medicare, anywhere in the U.S. | May need to use the plan's network and service area for non-emergency care |
| Specialists | "In most cases you don't need a referral" | May need a referral |
| Medigap | Can be bought to help with out-of-pocket costs | "You can't buy Medigap to cover your out-of-pocket costs" |
| Yearly out-of-pocket limit | None, unless there's supplemental coverage | Yes; after it, "you'll pay nothing for covered services for the rest of the year" |
One consequence worth knowing before switching: moving from Medicare Advantage back to Original Medicare doesn't guarantee a Medigap policy. Medicare.gov says that after the Medigap Open Enrollment Period ends, "insurance companies don't have to sell you a Medigap policy, unless you have Medigap protections, called" guaranteed issue rights. If that matters to your parent, check before the change, not after.
Why review coverage if nothing has changed?
Because the plan can change even when your parent doesn't. CMS says Medicare health and drug plans can make changes each year to cost, coverage, and which providers and pharmacies are in their networks.
Each fall, plans send a Plan Annual Notice of Change (ANOC). Medicare.gov says it "includes any changes in coverage, costs, and more that will be effective in January," and advises: "If you don't get this important document, contact your plan." Finding it before it's recycled is half the job.
What does an annual review involve?
Gathering a few facts and comparing plans. We don't recommend specific plans, insurers or products. Medicare.gov's checklist for choosing a plan includes checking whether it "covers your prescriptions" and asking "your doctors and pharmacies if they're in network with the plan." That means collecting:
- The current medication list, with doses: Medicare.gov says to add "all the prescription drugs you take regularly to get the most accurate monthly and yearly cost estimate"
- The doctors and hospitals your parent wants to keep seeing
- The Annual Notice of Change, read for what's moving rather than filed
- What was spent out of pocket this year, to compare with what was expected
- Anything new in their life: a move, a diagnosis, a new prescription
Medicare runs its own plan comparison tool at Medicare.gov/plan-compare. Every state has a State Health Insurance Assistance Program (SHIP); Medicare.gov says SHIPs offer "free personalized health insurance counseling" and "aren't connected to any insurance company or health plan." Both are categories of help, not a company we're pointing you at.
Can you make changes on a parent's behalf?
Not automatically. Medicare.gov says: "We can't share any information about your Medicare account, like claims or billing, unless you give us written permission first." The form is the Authorization to Disclose Personal Health Information (CMS-10106), or your parent can give permission through their Medicare account. It's separate from a HIPAA authorization for doctors and from a power of attorney. Setting it up well before December 7 avoids a scramble near the deadline.
What questions are worth asking?
- Has the Annual Notice of Change arrived, and has anyone read it?
- Is every current medication still covered, at the same tier?
- Are your parent's doctors still in network for next year?
- What did they spend out of pocket this year, against what the plan's headline numbers suggested?
- Is the authorization in place so you can help without being turned away?
Frequently asked questions
When is the Medicare Annual Enrollment Period?
October 15 to December 7 each year, according to Medicare.gov and CMS; for 2027 coverage, October 15 to December 7, 2026. Changes take effect on January 1 of the following year. Outside it, changes are limited to other windows, such as Special Enrollment Periods for events like a move, so a calendar reminder each autumn can help.
What are the different enrollment periods for Medicare?
The main ones are the Initial Enrollment Period (seven months around a person's 65th birthday), the General Enrollment Period (January 1 to March 31, for signing up after missing the initial window), Open Enrollment (October 15 to December 7, to change plans), and the Medicare Advantage Open Enrollment Period (January 1 to March 31, only for people already in Medicare Advantage).
What can be changed during Open Enrollment?
Per Medicare.gov: you can join, drop or switch a Medicare Advantage plan (with or without drug coverage), switch between Original Medicare and Medicare Advantage in either direction, and join, drop or switch a Medicare drug plan if you're in Original Medicare. The plan must get the request by December 7.
Can you switch back and forth between Medicare Advantage and Original Medicare?
Yes, but only in set windows. Either direction can be changed during Open Enrollment, October 15 to December 7. People already in a Medicare Advantage plan can also return to Original Medicare from January 1 to March 31. After the Medigap Open Enrollment Period, insurers don't have to sell a Medigap policy without guaranteed issue rights, so check first.
What is the difference between Medicare Advantage and Original Medicare?
Per Medicare.gov, Original Medicare works with any doctor or hospital that takes Medicare and can be paired with Medigap, but has no yearly out-of-pocket limit on its own; "In most cases you don't need a referral to see a specialist." Medicare Advantage plans may require using the plan's network and getting referrals, can't be paired with Medigap, and do have a yearly limit.
If my parent's plan is working, can we ignore it?
You can. CMS says that if people are "satisfied that their current plans will meet their needs for next year and it's still being offered, they don't need to do anything." The reason to look anyway is that plans can change costs, coverage and networks each year, and the Annual Notice of Change lists what's moving.
Can I do this on my parent's behalf?
Not automatically. Medicare can't share information about your parent's Medicare account without their written permission, given on the Authorization to Disclose Personal Health Information form (CMS-10106) or through their Medicare account. It's separate from a HIPAA form or a power of attorney, so set it up before December.
Getting started
Every family's order is different. The plan this site builds asks four questions, including which state your parents live in, and puts the handful of steps that matter most for your family in order. It's free and takes about 90 seconds.
Related guides
Sources
- Medicare.gov, Joining a plan: Open Enrollment dates and changes, the Medicare Advantage Open Enrollment Period, and how to compare plans.
- CMS, Medicare Open Enrollment: The October 15 to December 7 window and reviewing plan materials.
- Medicare.gov, When does Medicare coverage start?: The Initial and General Enrollment Periods.
- Medicare.gov, Special Enrollment Periods: Changes allowed after life events such as a move.
- Medicare.gov, Compare Original Medicare and Medicare Advantage: How the two kinds of coverage differ.
- Medicare.gov, Buying a Medigap policy: The Medigap Open Enrollment Period and guaranteed issue rights.
- Medicare.gov, Plan Annual Notice of Change: What the ANOC contains and when it arrives.
- Medicare.gov, 5 tips for using Medicare: Giving Medicare written permission to talk to someone you trust.
- Medicare.gov, Other forms: The Authorization to Disclose Personal Health Information form (CMS-10106).
- National Institute on Aging, Paying for Long-Term Care: SHIP offices in each state.
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