By Mike Miligi, Certified Medicare Insurance Planner – Michael M Insurance Services
What it is, what you’re allowed to change, and what to watch for before you pick up the phone or sign anything.
Once a year, for seven weeks, Medicare hands every enrollee a rare thing: a no-questions-asked chance to change their mind. That window is the Annual Enrollment Period, or AEP, and it runs from October 15 through December 7 every year. Whatever you decide during that window takes effect January 1.
If you already have a plan you’re happy with, you technically don’t have to do anything — your coverage will simply continue. But “doing nothing” should be a decision you make on purpose, not a default you fall into. A lot can change in a year: your health, your medications, your doctors, even the plan itself. This guide walks through what AEP actually covers, what’s worth reconsidering, and how to steer clear of the scams that flood mailboxes and phone lines every fall.
AEP is the one stretch of the year when nearly anyone on Medicare can make changes to their coverage without needing to qualify for a special exception. It applies if you’re enrolled in Original Medicare, a Medicare Advantage plan, or a standalone Part D drug plan. During these seven weeks, you can:
Every change made during AEP takes effect on January 1 of the following year, regardless of whether you make the change on October 16 or December 6.
AEP does not guarantee your right to buy or switch a Medicare Supplement (Medigap) policy. Outside of your initial 6-month enrollment window or a qualifying event, insurers in most states can ask health questions and decline coverage or charge more based on your health. Rules on this vary meaningfully by state — some states offer broader guaranteed-issue protections than others — so this is one area worth checking against your specific state’s rules before assuming you can switch freely.
Medicare Advantage (Part C) plans are offered by private insurers as an alternative to Original Medicare, usually bundling in Part D drug coverage and often extra benefits like dental, vision, or hearing. AEP is your opportunity to compare this year’s plan offerings against what you’re enrolled in now. Insurers are allowed to change a plan’s costs, drug formulary, provider network, and extra benefits every single year — so a plan that fit perfectly in January can look quite different by the following fall.
Worth checking each year: your monthly premium, your annual out-of-pocket maximum, copays for the specialists you actually see, and whether your pharmacy and hospital network has changed.
Medigap policies work alongside Original Medicare to cover cost-sharing gaps — deductibles, copays, coinsurance. Unlike Medicare Advantage, Medigap plans are standardized by letter (Plan G, Plan N, and so on), so the benefits of a given plan letter are the same no matter which insurer sells it. That means shopping for a better rate on the same plan letter can genuinely save money — but as noted above, medical underwriting may apply if you’re switching outside a protected window. This is a good example of something that’s worth a direct conversation before acting.
Part D plans update their drug formularies, tiers, and pharmacy networks annually — often significantly. A medication that was a low copay tier last year can move to a higher tier, or drop off the formulary entirely, without much fanfare. This is one of the most commonly overlooked reasons people end up overpaying for the exact same prescriptions they’ve taken for years.
Rather than starting with “which plan is best,” it’s usually more useful to start with what’s changed in your own life since last year:
It’s still worth a quick review of your Annual Notice of Change letter, since the plan itself may have changed even if your health hasn’t.
Every fall, the volume of Medicare-related robocalls, direct mail, and cold calls spikes sharply — and a meaningful share of it is designed to mislead rather than inform. A few patterns worth knowing:
A simple rule of thumb: legitimate agents and plans are allowed to market to you, but they are not allowed to cold-call you without your prior consent, and Medicare itself will never call you uninvited to sell you anything. If you didn’t initiate the contact, treat it with caution — hang up, set the mailer aside, and reach out to someone you already trust to verify before acting.
AEP often gets confused with two other periods:
Your current plan automa cally con nues into the new year. That’s fine if your costs and coverage haven’t changed — but it’s worth confirming that’s actually true rather than assuming it.
Yes. AEP works in both direc ons — from Medicare Advantage into Original Medicare, or from Original Medicare into a Medicare Advantage plan.
Every change made during AEP takes effect January 1, whether you enroll on October 16 or December 6.
You can request a change any me of year, including during AEP. But outside your original enrollment window or a qualifying event, most states allow insurers to ask health ques ons and poten ally decline coverage or charge more — unlike Medicare Advantage and Part D, which don’t require underwri ng during AEP.
Yes, AEP is open enrollment for Part D too. Keep in mind that if you’ve gone 63 days or more without creditable drug coverage since you first became eligible, a late enrollment penalty may apply and stay a ached to your premium going forward.
No. Switching plans during AEP is exactly what the window is for and carries no penalty. Penal es relate to delays in ever enrolling in coverage, not to switching once you’re already enrolled.
Check the plan’s formulary for the upcoming year, not the current year’s — formularies are updated annually and typically posted before AEP begins. A pharmacist or the plan’s member services line can also run a coverage check against your medica on list.
AEP (Oct 15–Dec 7) is open to anyone on Medicare and allows the widest range of changes. The Medicare Advantage Open Enrollment Period (Jan 1–Mar 31) is only for people already in a Medicare Advantage plan, and allows just one addi onal switch.
Medicare will not call you unsolicited to sell a plan, and legi mate agents can’t cold-call you without documented prior permission. If you didn’t ini ate the contact, verify independently before sharing any personal informa on — look up a number yourself rather than using one provided in the mailer or call.
It’s not required, but a quick annual review is worth the ten minutes it takes — plan costs and coverage can change year to year even when your health hasn’t.
