The short answer
Medicare's open enrollment period runs from October 15 to December 7 each year, and changes you make take effect on January 1. During it you can switch from Original Medicare to a Medicare Advantage plan or back, move from one Medicare Advantage plan to another, and join, switch or drop a Medicare drug plan. Your plan must receive the request by December 7. Plans change their premiums, drug lists and networks every January and describe the changes in an Annual Notice of Change sent by September 30, so read it before deciding. If you are in a Medicare Advantage plan on January 1, a second window from January 1 to March 31 allows one change: to another Medicare Advantage plan or back to Original Medicare. Leaving a Medicare Advantage plan does not usually give you a right to buy a Medigap policy, so check that before you switch.
The dates that matter
Swipe sideways to see the whole table.
| Window | Dates | What it allows |
|---|---|---|
| Annual Notice of Change arrives | By September 30 | Your plan's list of changes for the coming year |
| Open enrollment | October 15 to December 7 | Switch between Original Medicare and Medicare Advantage, change plans, or join, switch or drop drug coverage |
| New coverage starts | January 1 | Any change made during open enrollment |
| Medicare Advantage open enrollment | January 1 to March 31 | One change, for people already in a Medicare Advantage plan |
The December 7 date is firm: the plan must receive your enrollment request by then. A request that arrives later generally waits for another enrollment period, unless you qualify for a special one.
What you can change
Open enrollment covers the two big choices in Medicare: how you get your health coverage and how you get your drug coverage. During it you can:
- Move from Original Medicare to a Medicare Advantage plan.
- Move from a Medicare Advantage plan back to Original Medicare.
- Switch from one Medicare Advantage plan to another.
- Join a Medicare drug plan, switch to a different one or drop drug coverage.
If you make no change, you generally stay in the plan you have, with its new costs and rules for the coming year. Our guide to Original Medicare and Medicare Advantage compares the two routes in detail.
Start with the Annual Notice of Change
Medicare Advantage and drug plans send each member an Annual Notice of Change in September, with a printed copy by September 30. It lists what changes in January: the premium, the deductible, copayments, the list of covered drugs, the pharmacies and doctors in the network and the area the plan serves. If you did not receive it, contact your plan.
Read it with three questions in mind. Will your premium or deductible rise? Are all of your drugs still covered, and at what cost? Are your doctors, hospitals and pharmacy still in the network? A yes to the first or a no to either of the others is a reason to compare plans.
What is different for the coming year
Drug coverage has a yearly cap on out-of-pocket costs, and it rises from $2,100 in 2026 to $2,400 in 2027. Once your spending on covered Part D drugs reaches the cap, you pay nothing more for covered drugs that year. CMS projects the average monthly premium for a stand-alone drug plan to rise by less than a dollar, to about $36, but plans vary widely around that figure.
The Part B premium for the coming year is set separately by Medicare and applies whichever way you choose to get coverage. Our guide to Medicare costs explains the premiums and deductibles, and our guide to Part D and the drug cap covers drug costs in depth.
How to compare plans
- List your prescriptions, with the dose and how often you take them, and the pharmacy you use.
- List your doctors and hospitals, especially any specialist you see regularly.
- Use the Medicare Plan Finder at Medicare.gov to compare the plans in your area by total yearly cost, not premium alone.
- Check each plan's network and drug list against your lists, including any prior authorization or step therapy rules.
- Enroll before December 7 through the Plan Finder, by calling the plan or by calling 1-800-MEDICARE.
Example (hypothetical): a notice worth reading
Frank's drug plan notice says his premium rises by $12 a month next year and one of his three medications moves to a more expensive tier. He enters his three drugs and his pharmacy in the Plan Finder and finds two plans in his area with a lower total yearly cost, one of them with a higher premium but much lower costs for his drugs.
He joins that plan on November 20. His new coverage starts January 1, and joining it ends his old drug plan automatically, so there is nothing else to cancel.
Free, unbiased help is available from your State Health Insurance Assistance Program, or SHIP, which is funded by the federal government and not connected to any insurance company. Your state's SHIP can be found through shiphelp.org.
Calls and ads that are not Medicare
Open enrollment is also the busiest season for Medicare marketing. Medicare itself does not call people to sell plans, and plans are not allowed to make unsolicited sales calls. A caller who asks for your Medicare number to update your coverage or to send a new card is a warning sign; hang up and call the number on your plan card or 1-800-MEDICARE instead. Our guide to benefit scams lists the other common approaches.
The Medigap catch
Switching from Medicare Advantage back to Original Medicare is easy during open enrollment. Buying a Medigap policy to go with it may not be. Federal law gives you a guaranteed right to buy a Medigap policy only in certain situations, such as your six-month Medigap open enrollment period when you first take Part B at 65 or older, or when a Medicare Advantage plan leaves Medicare.
Outside those situations, Medigap insurers in most states can review your health before selling you a policy, and can charge more or say no. One protection helps people who are new to Medicare Advantage: if you joined a Medicare Advantage plan for the first time and are still within your trial period, you may have a right to return to Original Medicare and buy a Medigap policy. When you do have a guaranteed right after leaving Medicare Advantage, you must apply for Medigap no more than 63 days after your Medicare Advantage coverage ends.
If you miss December 7
If you are in a Medicare Advantage plan on January 1, you get a second chance from January 1 to March 31. During it you can make one change: to a different Medicare Advantage plan, or back to Original Medicare, where you can also join a drug plan. The change takes effect on the first day of the month after the plan receives your request.
People in Original Medicare do not get that second window. Outside open enrollment, they can change only if they qualify for a special enrollment period, such as after moving out of a plan's service area or when a plan stops serving their area. If you might also qualify for help with costs, our guide to Medicare Savings Programs explains programs with their own rules.
Common questions
What happens if I do nothing during open enrollment?
You generally stay in your current plan for the coming year, with whatever changes it made to premiums, drug coverage and networks. Read your Annual Notice of Change to see what those are.
Can I change Medigap policies during open enrollment?
Open enrollment does not give you a right to buy or switch a Medigap policy. Outside your Medigap open enrollment period or a guaranteed issue situation, insurers in most states can review your health before selling you a policy.
Can I join Medicare Advantage in January instead?
Not from Original Medicare. The January 1 to March 31 window is only for people already in a Medicare Advantage plan. People in Original Medicare join a Medicare Advantage plan during open enrollment, or when a special enrollment period applies.
When does a change made in November take effect?
Any change made during open enrollment, whether in October, November or by December 7, takes effect on January 1.
Official sources
Put an hour on the calendar before December
The comparison takes an hour or two with your lists in hand, and it is easier with weeks to spare than on the last day. Read your plan's notice, run the Plan Finder, and if the best plan is the one you have, you need do nothing. For a sense of what the year ahead will cost, the Medicare calculator estimates premiums and out-of-pocket costs, and our guide to Medicare and Medicaid explains how the two programs fit together if your income is limited.
