Open Enrollment is the one Medicare window nearly everyone gets to use every single year, and it’s also the one most people skip through inertia—letting their current plan auto-renew without checking whether it still makes sense. Given the scope of changes rolling out for 2027 (a redesigned Part D structure, rising Part B premiums, and some Medicare Advantage plans trimming benefits), this year is a particularly important one to actually work through the checklist rather than assume last year’s plan is still your best option.
What This Article Covers
- Know the Timeline
- Step 1: Read Your Annual Notice of Change
- Step 2: Check Your Medications Against the Formulary
- Step 3: Confirm Your Doctors and Pharmacy Are Still In-Network
- Step 4: Compare Total Annual Cost, Not Just Premium
- Step 5: Decide — Stay, Switch, or Reconsider Original Medicare
- Step 6: Make Your Change Before December 7
- Frequently Asked Questions
Know the Timeline
The Annual Enrollment Period (AEP)—what most people mean by “Medicare Open Enrollment”—runs October 15 through December 7 every year. Any changes you make take effect January 1 of the following year. Miss this window, and your only other opportunity to make a broad change is the more limited Medicare Advantage Open Enrollment Period (January 1–March 31), which allows just one plan switch and only if you’re already in a Medicare Advantage plan. There’s no general Original Medicare “regret window” outside AEP, so this seven-and-a-half-week period genuinely matters.
Step 1: Read Your Annual Notice of Change (ANOC)
Every Medicare Advantage and Part D plan is required to send an Annual Notice of Change by September 30, detailing exactly what’s different about your plan for the coming year—premium, deductible, copays, covered benefits, and formulary changes. This document is the single most important piece of mail you’ll receive all year in relation to your healthcare costs, and it’s worth reading in full rather than skimming the summary. Given that some Medicare Advantage plans are trimming extra benefits for 2027 (see Why Some Medicare Advantage Plans Are Cutting Benefits in 2027), don’t assume this year’s ANOC looks like last year’s.
Step 2: Check Your Medications Against the 2027 Formulary
Part D formularies—the list of covered drugs and what tier they fall into—can change from year to year even within the same plan. With the Part D deductible rising to $700 and the out-of-pocket cap rising to $2,400 for 2027 (see Medicare Part D Changes for 2027), it’s worth running your specific medication list through Medicare’s Plan Finder tool to see your actual projected annual cost under your current plan versus alternatives, rather than assuming the premium alone tells the story.
Step 3: Confirm Your Doctors and Pharmacy Are Still In-Network
If you’re in a Medicare Advantage plan, provider networks can shift year to year, sometimes significantly if an insurer is narrowing its network in response to the tighter 2027 payment environment. Call your doctor’s office directly, or use your plan’s online provider directory (cross-checked against Medicare.gov, since directories aren’t always current), to confirm your primary care doctor, key specialists, and preferred pharmacy remain in-network for 2027 before you commit to staying in your current plan.
Step 4: Compare Total Annual Cost, Not Just Premium
| What to Compare | Why It Matters |
|---|---|
| Monthly premium | The most visible number, but not the whole picture |
| Deductible | Rising to $700 max for Part D in 2027 |
| Copays/coinsurance for your specific care patterns | Where costs actually accumulate through the year |
| Annual out-of-pocket maximum | Your real financial ceiling for the year |
| Drug formulary tier for your specific medications | Determines what you actually pay at the pharmacy |
| Extra benefits actually included for 2027 | Advertised benefits may be reduced from prior years |
A plan with a slightly higher premium but a lower out-of-pocket maximum, or better formulary placement for your specific medications, can easily cost less overall than a flashier $0-premium alternative. Running your actual numbers—not just comparing headline premiums—is the only reliable way to know.
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Step 5: Decide—Stay, Switch, or Reconsider Original Medicare
With your ANOC reviewed, your medications checked, and your network confirmed, you’re in a position to make an informed decision: stay with your current plan, switch to a different Medicare Advantage or Part D plan, or reconsider Original Medicare with a Medigap policy if you’re currently in Medicare Advantage and increasingly value provider flexibility over bundled extras. For a full side-by-side comparison of that broader decision, see Medicare Advantage vs. Original Medicare: Which Is Actually Better? Note that switching to Medigap outside your initial Medigap Open Enrollment window may involve medical underwriting, so that decision deserves its own careful research beyond this AEP checklist.
Step 6: Make Your Change Before December 7
If you decide to switch plans, submit your change through Medicare.gov, by calling 1-800-MEDICARE, or through your plan directly, well before the December 7 deadline—waiting until the final days increases the risk of processing issues. If you’re satisfied after reviewing everything above and decide to stay put, you don’t need to do anything; your current plan will continue into 2027 as described in your ANOC. Either way, you’ll have made an informed decision rather than an accidental one.
Why It’s Worth the Effort Even If You’re Happy With Your Plan
A natural question is why anyone should go through this full checklist if they’re generally satisfied with their current coverage. The honest answer is that “satisfied” is a moving target, because the plan itself can change underneath you even when nothing in your own health or preferences has shifted. A plan that felt like an excellent fit in 2026 can quietly become a mediocre fit for 2027 through a combination of small changes—a slightly higher copay here, a formulary tier shift there, a
trimmed OTC allowance—none of which individually feels dramatic, but which can add up to a meaningfully worse deal by the time you notice, often not until you’re already using the plan partway through the year.
There’s also a competitive dynamic worth understanding: insurers know that inertia is powerful and that a large share of enrollees will auto-renew regardless of whether a better option exists. This isn’t a criticism of any particular insurer—it’s simply how insurance markets with high switching friction tend to behave. The practical implication is that “best value” and “current plan” aren’t the same thing by default, and only actually running the comparison finds out which one applies to your specific situation this year.
Finally, treating this as an annual ritual rather than a one-time decision pays off precisely because Medicare itself keeps evolving — new Part D cost structures, shifting Medicare Advantage payment rates, and updated CMS rules all mean that the “right” choice for your situation isn’t static. Setting aside even an hour each October to work through this checklist is a small time investment relative to the potential cost of an unexamined auto-renewal, especially in a year like 2027 with as many moving pieces as this one has.
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Frequently Asked Questions
When is Medicare Open Enrollment for 2027?
The Annual Enrollment Period (AEP) runs October 15 through December 7, 2026. Changes made during this window take effect January 1, 2027.
What can I change during Open Enrollment?
You can switch from Original Medicare to Medicare Advantage or back, switch between Medicare Advantage plans, switch or enroll in a Part D drug plan, or drop Part D coverage entirely.
What happens if I do nothing during Open Enrollment?
Your current plan generally auto-renews, but its premiums, benefits, and formulary can still change for the new year—meaning doing nothing can mean unknowingly accepting a worse deal than you had.
Do I need to review my plan every year even if I’m happy with it?
Yes, it’s strongly recommended. Plans change premiums, formularies, provider networks, and extra benefits annually, so a plan that fit well last year may not be the best fit for 2027.
Can I switch Medigap policies during Open Enrollment?
Open Enrollment (Oct 15–Dec 7) is specifically for Medicare Advantage and Part D changes. Switching Medigap policies isn’t tied to this window and may involve medical underwriting outside your initial Medigap Open Enrollment Period.
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This checklist is for general educational purposes. Enrollment deadlines and rules are set by CMS and may be subject to change—confirm current dates and procedures at Medicare.gov.
Senior Affair is not affiliated with the federal Medicare program.
