Medicare Annual Enrollment — when and why to review the plan every year

Reviewed by the How To Help Your Elders Team | Updated March 2026

Medicare plans change every year. Formularies shift, networks shrink, premiums climb, and copays increase. The Annual Enrollment Period runs October 15 through December 7, and it is the one window each year when your parent can switch plans or adjust coverage before changes take effect January 1.

Everything About Your Parent's Plan Changes Every Year, Whether They Notice or Not

Your father switched to a Medicare Advantage plan three years ago because the premium was lower than Original Medicare with a supplement. The plan seemed fine. This year, he got a letter saying his plan is making changes. One of his three medications moved to a higher cost tier. His favorite orthopedist is leaving the network. His copay for physical therapy went up. The plan is "changing" and he has thirty days to decide whether to stay or switch. Or maybe he doesn't remember getting the letter. Maybe he got it, didn't understand what it meant, and threw it away.

This is how it works for millions of Medicare beneficiaries every year. According to CMS, Medicare Advantage plans and Part D plans submit new benefit designs annually, and formulary changes affect a significant portion of enrollees. What worked perfectly for your parent last year might not work this year. And every year, Medicare gives beneficiaries a narrow window to respond.

If your parent doesn't pay attention and doesn't make changes, they're stuck with whatever happened to their current plan. If they change plans without reading carefully, they might end up worse off. The sweet spot is reviewing the plan every year and being intentional about whether to stay or switch.

Why Plans Change: Networks, Formularies, and Costs

Medicare plans aren't static. If your parent is on a Medicare Advantage plan, the network changes. Doctors leave. Copays increase. Sometimes benefits shift, like how much physical therapy is covered or whether certain types of care are included. The plan your parent has now isn't the same plan they'll have next year unless you actively review and confirm that staying makes sense.

If your parent has Part D prescription drug coverage, the formulary changes every year. The formulary is the list of medications the plan covers. Medications move to higher cost tiers or get dropped entirely. Your parent's diabetes medication might be on the formulary at a low copay this year, but next year the plan might prefer a different medication and move your parent's to a higher cost tier. That means monthly out-of-pocket costs go up, or your parent has to switch medications.

Premiums also increase most years. The standard Part B premium increases. Medicare Advantage plan premiums might increase. Part D premiums increase. Even if nothing else changed, your parent would be paying more next year. According to CMS data, the standard Part B premium has increased in most years over the past decade. KFF research shows that Medicare Advantage plan benefits and cost-sharing structures vary significantly from year to year, even within the same plan.

Deductibles shift too. If your parent is in a Medicare Advantage plan with a deductible, the deductible might increase. If they have Original Medicare with a supplement, the supplement premiums might increase and copays might change.

When you add all these changes together, your parent's total out-of-pocket costs can increase significantly. A plan that was good this year might not be good next year.

The October-December Window: Mark Your Calendar Now

Medicare Annual Enrollment Period runs from October 15 through December 7 every year. This is when your parent can make changes to their Medicare coverage. Any changes made during this window take effect January 1 of the following year.

This is the main enrollment window. If your parent misses it, they have to wait until the next year to make changes. So if your parent forgets to review their plan in November, they're stuck with whatever plan they have for the whole next year.

There are other enrollment windows, like if your parent moves or has a qualifying life event. But those don't apply to most people in most years. October through December is the window that matters.

October 15 is early enough that you can review and make decisions without rushing. December 7 is early enough that changes take effect on January 1. If your parent waits until late December to decide, it's too late.

Your job is to make sure your parent knows these dates and to help them review their plan during this window. Put it on your calendar. Send your parent a reminder in early October. Make the appointment in October to review the plan together. Get decisions made by early December so there's time to complete any changes.

What You Need to Check Every Year

Start with medications. What medications is your parent currently taking? Get a complete list. Go through the medicine cabinet if you need to. Write down the exact name of each medication, the dose, and how much they take per day. This matters because the pharmacy or your parent might refer to a medication generically ("blood pressure medicine") but there are multiple blood pressure medications, and they're not all on every formulary.

When you have the list, check the current plan's formulary for next year. The formulary is available on the plan's website and through the Medicare.gov Plan Finder tool. Go through each medication and see what tier it's on. Tier one drugs have the lowest copay. Higher tiers mean higher copays. Look at the copay for each of your parent's medications and add them up. That's what your parent will pay for drugs under the current plan next year.

Then compare. If your parent's top three medications are moving to higher cost tiers, that could mean a significant increase in drug costs. That's information you need when deciding whether to switch plans.

Next, check doctors. If your parent is on a Medicare Advantage plan, the doctor network might change. Is your parent's doctor still in network next year? Call the doctor's office if you're not sure. If the primary care doctor is leaving the network, that might be reason enough to switch plans. Your parent shouldn't stay on a plan where their doctor is no longer available unless the plan is otherwise a strong fit.

Then look at total costs. Get out your parent's claims from this year. How much did they spend out of pocket? Between premiums, deductibles, copays, and coinsurance, what was the total? Estimate what next year will cost based on the new plan's numbers. If total out-of-pocket costs are going to increase significantly and there's a plan with lower costs, switching makes sense.

Don't just look at the premium. A plan with a higher premium but lower deductibles and copays might actually cost less in total. A plan with a lower premium but higher copays might cost more. The premium is the number people focus on because they see it every month, but total annual cost is what matters.

When to Switch Plans and When Staying Makes More Sense

If your parent's prescription costs are increasing by more than fifty or a hundred dollars a month because of formulary changes, switching makes sense. If their doctor is leaving the network and there's no comparable doctor remaining, switching makes sense. If they're looking at a significant overall increase in total out-of-pocket costs and a better plan is available, switching makes sense.

Switching also has a cost. You have to understand the new plan. You have to update where prescriptions get filled. You have to tell doctors about the change. You have to learn the new plan's procedures. There's real effort involved.

Small increases probably don't justify the switching effort. If copays are going up by a few dollars for each medication and the doctor is still in network, staying might make more sense. Your parent is familiar with the plan. Everything is already set up. A small cost increase is sometimes worth the stability.

Also consider whether your parent is actually likely to follow through on a switch. Some people feel overwhelmed by making changes. They'd rather know what they have than take a chance on something unknown. For people like this, switching multiple times creates stress. Once every few years to address a major problem might be appropriate, but constant switching isn't good for peace of mind.

The decision to switch or stay depends on your parent's situation. Significant cost increases with a clear alternative mean switch. Small increases with current satisfaction mean stay. You're finding the balance between the best coverage and stability.

Tools That Make Comparison Easier

Medicare.gov has a Plan Finder tool that is genuinely useful. You enter the medications your parent takes and the doctors they see, and the tool shows what different plans would charge for those specific medications and whether those doctors are in network. According to Medicare.gov, the Plan Finder compares all plans available in your parent's zip code and estimates total annual costs including premiums, deductibles, and drug copays.

This answers the exact question you care about: "If my parent switches to this plan, how much will it cost, and will their doctors still be available?"

SHIP counselors can also help with plan comparison. Every state runs a State Health Insurance Assistance Program with trained counselors who know the plans available locally, which plans have good reputations, and which have problems. SHIP counselors are free, unaffiliated with insurance companies, and funded by the federal government. Your parent can find their state's SHIP program at shiphelp.org or by calling 1-877-839-2675.

Some insurance brokers specialize in Medicare. These brokers are paid by the plans, not by you. They have time to help you think through options and can compare plans side by side.

Making Changes Before the Deadline

Once you and your parent have decided whether to stay or switch, take action. If you're staying with the current plan, you probably don't need to do anything. Most plans auto-renew. Your parent will be on the same plan January 1 unless they take action to change.

If you're switching, you can go online to Medicare.gov and make the change, call the plan and request a change, or have a SHIP counselor or insurance broker help. Whichever way you do it, make sure you understand what you're switching to and that the new plan actually covers what you need.

Some Medicare Advantage plans have lock-in considerations. If your parent switches from a Medicare Advantage plan to Original Medicare, they might not be able to switch back to Medicare Advantage the following year if their health situation has changed. The plan might deny enrollment. So once you switch away from Medicare Advantage, returning might not be straightforward. This isn't necessarily bad, since Original Medicare is solid coverage. But you should know what you're committing to before you switch.

Keep documentation of any changes. If you switched plans online, print the confirmation. If you called, keep notes about who you talked to and when. If something goes wrong, you have proof the change was requested.

Once any change takes effect, follow up. Did your parent receive the card for the new plan? Is the new plan billing correctly? Can your parent access their doctors? Are prescriptions being filled under the new plan? Follow up in the weeks after the change takes effect to make sure the transition actually happened.

Annual enrollment isn't optional in the sense that your parent's plan will change whether they review it or not. Paying attention every year helps make sure they're not overpaying and not losing access to doctors they want to see. A few hours of work in October and November saves money and prevents problems throughout the year.

Frequently Asked Questions

What happens if my parent misses the Annual Enrollment Period?
If your parent misses the October 15 through December 7 window, they're generally stuck with their current plan until the next Annual Enrollment Period. There are exceptions if they qualify for a Special Enrollment Period due to moving, losing coverage, or other qualifying life events, but for most people, missing the deadline means waiting another year.

Can my parent switch from Medicare Advantage back to Original Medicare?
Yes, during the Annual Enrollment Period (October 15 through December 7). There is also a Medicare Advantage Open Enrollment Period from January 1 through March 31 when your parent can switch from one Medicare Advantage plan to another or drop Medicare Advantage and return to Original Medicare.

Does my parent have to do anything if they want to keep their current plan?
No. Medicare plans auto-renew. If your parent is happy with their current plan and the changes for next year are acceptable, they don't need to take any action. But they should still review the Annual Notice of Change letter to understand what's different.

How do I find out what's changing in my parent's plan for next year?
The plan sends an Annual Notice of Change (ANOC) letter by September 30 each year. This letter details every change to the plan for the coming year, including premium changes, formulary changes, network changes, and benefit changes. If your parent didn't receive this letter or can't find it, call the plan directly or check Medicare.gov.

Is SHIP really free?
Yes. SHIP is federally funded and completely free. SHIP counselors are not affiliated with any insurance company and do not receive commissions. They exist specifically to help Medicare beneficiaries understand their options and make informed decisions.