Open enrollment for Medicare runs from October 15 to December 7, and what you do in those eight weeks sets your costs for the whole next year.
Most people treat it as a chance to shop. It is better understood as a chance to review, because the plan you already hold is changing whether you look at it or not.
In this guide I’ll walk you through which window you are actually in, the six things to check in your own paperwork, and the one switch that can be harder than it looks.
Staying put is a legitimate answer, and by the end you will know whether it is yours.
Where Medicare Leaves Gaps Open
Medicare was never designed to stand on its own.
Part A carries a hospital deductible for each benefit period rather than each year, so more than one stay in a year can mean paying it more than once. Part B leaves 20% coinsurance behind it with no ceiling.
Routine dental, vision, and hearing sit outside Original Medicare entirely. So does most care you receive outside the United States.
Those gaps are why Medicare supplement plans and Medicare Advantage plans exist, and closing them is what your review is really about.
None of that is a sign something went wrong. It is how the program was built, and every private option on the market exists to fill some part of it.
Knowing the gaps tells you which plan is worth its premium.
Which Open Enrollment for Medicare Window Are You In?
Three different windows share similar names, and mixing them up is the most common mistake I see.
- October 15 to December 7: The fall window, which Medicare calls Open Enrollment and the industry calls the Annual Enrollment Period. Changes take effect January 1.
- January 1 to March 31: The Medicare Advantage Open Enrollment Period. If you already hold a Medicare Advantage plan, you can make one change.
- Six months from your Part B start: The Medigap Open Enrollment Period, beginning the first month you are both 65 or older and enrolled in Part B.
That third window is the one that matters most and gets the least attention. During it, insurers must sell you any Medicare supplement plan offered in your state at the best available rate, regardless of your health history.
Open enrollment for Medicare in the fall is the window most people mean, so that is the one this guide follows.
Start Your Open Enrollment Review With the Annual Notice
Your review starts with a letter, not a website.
Every Medicare Advantage and Part D plan sends an Annual Notice of Change by late September. It lists every adjustment to your premium, deductible, drug list, and benefits for the coming year.
Read it beside your current plan documents rather than on its own. The changes only mean something in comparison.
If it went in the recycling, your plan can send another copy before open enrollment for Medicare closes.
What Changes on January 1 Whether You Act or Not
Your plan is not standing still while you decide.
Medicare health and drug plans can change their costs, their benefits, their provider networks, and their pharmacy networks each year. Every one of those changes takes effect January 1 whether or not you opened the letter.
The government figures move as well. CMS publishes the following year’s Part A and Part B amounts each fall, so the numbers in your current paperwork are always a year behind for part of the season.
That is the whole case for reviewing rather than renewing. Nothing about your plan is guaranteed to look the same in January.
The only variable you control during open enrollment for Medicare is whether you noticed.
Check Your Premium and Out-of-Pocket Maximum
Premiums get all the attention, and the out-of-pocket maximum decides your worst year.
For 2026, the standard Part B premium is $202.90 per month with a $283 annual deductible, and the Part A hospital deductible is $1,736 per benefit period. Those figures come from the CMS cost fact sheet and are updated each fall.
Original Medicare has no out-of-pocket maximum at all. Medicare Advantage plans must set one, capped at $9,250 in network for 2026.
Those two numbers move in opposite directions across most plans, which is why a low premium tells you almost nothing on its own.
Compare the number you could owe in a bad year, not just the number you pay every month.
Check Every Prescription Against the Formulary
This is where the expensive surprises hide.
Drug lists change every year. A medication can move to a higher tier, require prior authorization, or leave the list entirely, and none of that changes your premium.
For 2026 the Part D deductible tops out at $615, and once your out-of-pocket drug spending reaches $2,100 you pay nothing more for covered drugs that year.
Check each prescription by name and dose, because a tier change on one drug can outweigh every premium difference on your list.
The Two Ways to Get Drug Benefits
Most people have a choice here and never realize it.
You can hold a standalone Part D plan alongside Original Medicare, or you can hold a Medicare Advantage plan that bundles drug benefits into the same policy.
The bundled route looks simpler, and it ties two decisions together. If the drug side stops working for you, you generally cannot fix it without changing your medical plan as well.
The standalone route keeps the decisions separate, so a bad drug year does not force you to rebuild everything. Joining or switching a plan follows the same October 15 to December 7 calendar either way.
Separating the two costs a little more paperwork and buys a lot more flexibility.
If Your Drug Costs Are Straining Your Budget
One program is worth checking before you change anything.
Extra Help is a federal program that lowers Part D premiums, deductibles, and copays for people under certain income and resource limits. Social Security administers it.
It does not change which plan suits you, but it changes what any plan costs you. Check eligibility before you rule out a plan on price alone.
It costs nothing to find out and it can change the arithmetic entirely.
Check That Your Doctors Are Still in Network
Networks move as quietly as drug lists do.
A Medicare Advantage plan can add or drop providers each year, and a hospital system can leave a network mid-contract. Original Medicare works differently, since any provider who accepts Medicare will see you.
Call the office of every doctor you want to keep and ask whether they will accept your specific plan next year. Directories run out of date faster than the people maintaining them would like.
Ten phone calls now beats one surprise bill in March.
Want to see what a supplement plan would cost you next year?
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What Star Ratings Tell You Before Open Enrollment
Star ratings are useful, and they are not the whole story.
Medicare scores plans from one to five stars on measures such as customer service, complaints, and how well the plan manages chronic conditions. A low rating is a genuine warning sign.
What the rating cannot tell you is whether your doctors are in the network or your drugs are on the list. Use it as a tiebreaker between two plans that already pass your own checks.
Treat the rating as one input among several during open enrollment for Medicare.
The Medicare Underwriting Trap When You Switch to a Supplement Plan
Not every switch works in both directions, and this is the part that catches people.
Moving between Medicare Advantage plans during the fall window is straightforward, and no health questions are involved. Moving from a Medicare Advantage plan to a Medicare supplement plan is different.
Outside your Medigap Open Enrollment Period, and outside a guaranteed issue right, an insurer can ask about your health history and decline you or charge more. Our guide on how Medigap underwriting works covers what the questions look like.
Guaranteed issue rights exist in specific situations, such as losing employer benefits or leaving a Medicare Advantage plan within your first year on it.
Check which rights apply to you before you drop anything you might not get back.
Standardized Plans Mean You Are Shopping on Price and Service
Here is the piece that makes the supplement side simpler than it looks.
What many people do not realize is that Medigap plans are standardized by federal law. A Plan G from one company is identical in benefits to a Plan G from another company.
The differences come down to pricing, service, and extras. Our job is to find you the best price for the same benefits, which is why comparing several carriers matters more than picking a familiar name. You can see how the plan letters compare side by side.
Once you know your letter, the rest is arithmetic.
Medicare Advantage and Original Medicare Side by Side
The real choice sits one level above plan letters and star ratings.
Original Medicare paired with a supplement plan gives you any provider who accepts Medicare, no referrals, and predictable costs, in exchange for a monthly supplement premium.
A Medicare Advantage plan often carries a low or zero premium and bundles extras, in exchange for a network, referral rules, prior authorization, and cost sharing up to the plan’s out-of-pocket maximum.
Original Medicare on its own is the option to avoid, since it caps nothing. Our comparison of the two routes lays out where each one fits.
Neither is better in the abstract, and one is usually better for you.
A Two-Week Open Enrollment Review Plan Before December 7
Break the review into small pieces and it stops feeling like a project.
- Days 1 and 2: Read the Annual Notice of Change and mark every line that moved.
- Days 3 to 5: Check each prescription by name and dose against next year’s drug list.
- Days 6 to 8: Call every doctor and hospital you want to keep and ask about next year specifically.
- Days 9 and 10: Compare your current plan against two alternatives on total annual cost.
- Days 11 to 14: Make the change, or decide deliberately to stay, and write down why.
Two weeks of small steps beats one afternoon of guessing.
Questions to Ask Before You Switch Anything
A good switch survives these five questions.
- Will every one of my prescriptions be on the list next year, at what tier, and with what restrictions?
- Are my doctors and my hospital in the network for the coming year, confirmed by their own office?
- What is the most I could pay in a bad year under this plan?
- If I leave a Medicare Advantage plan, can I get a supplement plan back when I want one?
- Am I switching because the plan changed, or because the premium looks lower?
If any answer is a shrug, keep asking before December 7 arrives.
Late Enrollment Penalties Are Permanent
One cost follows you for life, and it is entirely avoidable.
If you go 63 days or more without creditable drug benefits after becoming eligible, Medicare adds a Part D late enrollment penalty to your premium. It is calculated as a percentage and it does not expire.
Part B carries its own late enrollment penalty, and that one also lasts as long as you hold the plan.
Neither penalty is triggered by open enrollment for Medicare itself, but the fall window is when most people discover they have one.
If you think a penalty applies to you, ask before you shop rather than after.
How to Prepare for Open Enrollment for Medicare in September
The work that makes this easy happens before October 15.
Gather your current plan documents, your Annual Notice of Change, a full list of prescriptions with doses, and the names of every doctor and hospital you use.
Then write down what you actually spent this year on premiums, copays, and drugs. That total is the benchmark every alternative has to beat.
Preparation in September turns a two-month decision into a two-week one.
When Staying Put Is the Right Answer During Open Enrollment
Sometimes the review ends with no change at all, and that is a win.
If your premium held steady, your drugs stayed on their tiers, and your doctors are still in network, your plan is doing its job. Switching for its own sake carries real risk, especially on the supplement side.
The point of open enrollment for Medicare is not to change something. It is to make sure you know what you are holding.
Every year I talk to people who used open enrollment for Medicare to confirm their plan rather than replace it, and they finish the season better informed than the ones who switched on price alone.
A deliberate decision to stay is nothing like an accidental one.
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Open Enrollment for Medicare FAQs
Q: When is open enrollment for Medicare?
A: Open enrollment for Medicare runs October 15 to December 7 every year.
Your plan must receive your request by December 7, and any change takes effect January 1. A separate Medicare Advantage window runs January 1 to March 31 for people already in one of those plans.
Q: Can I switch from Medicare Advantage to a supplement plan?
A: You can apply at any time, though approval is not guaranteed.
Outside your Medigap Open Enrollment Period or a guaranteed issue right, insurers can review your health history and decline you. Check which rights apply before you leave a plan you may not be able to rejoin.
Q: What happens if I do nothing during open enrollment for Medicare?
A: Your current plan renews automatically with whatever changes the Annual Notice of Change described.
Premiums, drug tiers, networks, and benefits can all shift. Auto-renewal is how most unpleasant surprises reach people in February rather than in October.
Q: Does open enrollment for Medicare apply to Medigap plans?
A: Not directly.
The fall window governs Medicare Advantage and Part D. Medicare supplement plans have no annual window at all, so you can apply any month, subject to underwriting unless a guaranteed issue right or your own six-month Medigap window applies.
Q: How long do I have to review my Annual Notice of Change?
A: It arrives by late September, which gives you roughly two weeks before the window opens on October 15.
Use them. Reviewing early leaves time to call your doctors and check your prescriptions before the December 7 deadline arrives.
For Further Reading:
Leslie Alford is a Personal Benefits Manager at MediGap Advisors. Leslie has a passion for bringing clarity to those confused about Medicare. She is an authority on Medicare, Medicare supplement plans, Medicare Advantage plans, and Part D prescription drug plans. Read more about Leslie on her Bio page.