Susan Park
October 15th. Write it down. That’s when it starts.
Medicare’s Annual Enrollment Period (AEP) runs from October 15 through December 7 every year, and 2026 is no different. Any changes you make take effect January 1, 2027. Miss December 7th and you’re locked into whatever coverage you have now for another full year, with very limited exceptions.
I’ve watched people miss this window by a week, sometimes by a single day, and spend the next twelve months paying for a plan that doesn’t fit them anymore. One woman I spoke with, Barbara from Phoenix, had switched to a lower-cost Part D plan (that’s Medicare’s prescription drug coverage) the prior year without checking whether her cholesterol medication was still on the plan’s formulary (the list of covered drugs). It wasn’t. She spent most of the year paying full retail for a drug that should have cost her $12 a month. The fix was simple. She just didn’t know she needed to make it.
That’s what open enrollment is for.
What You Can Actually Change During AEP
| Action | During AEP (Oct 15-Dec 7) | Outside AEP |
|---|---|---|
| Switch Original Medicare to Medicare Advantage | ✓ Allowed | Limited exceptions only |
| Switch Medicare Advantage to Original Medicare | ✓ Allowed | Limited exceptions only |
| Switch between Medicare Advantage plans | ✓ Allowed | Limited exceptions only |
| Join or switch Part D drug plans | ✓ Allowed | Limited exceptions only |
| Drop Part D coverage | ✓ Allowed | Limited exceptions only |
| Add, change, or drop Medigap plans | ✗ Not covered by AEP | Separate rules apply; health questions may be asked |
This is where most articles get vague. Let’s be specific.
During the October 15 to December 7 window, you can:
- Switch from Original Medicare (Parts A and B) to a Medicare Advantage plan (Part C)
- Switch from a Medicare Advantage plan back to Original Medicare
- Switch from one Medicare Advantage plan to a different one
- Join a standalone Part D drug plan if you don’t have one
- Switch from one Part D plan to another
- Drop Part D coverage entirely (though I’d almost never recommend this)
What AEP does NOT cover: Medigap (Medicare Supplement Insurance) plans. Those operate on their own rules entirely. If you want to add, change, or drop a Medigap plan, you generally need to apply separately, and insurers can ask health questions and potentially deny you outside of your initial enrollment period. That’s a common source of confusion, and honestly, the two systems sitting side by side without a clear label is one of Medicare’s less charming design choices.
Why 2026 Makes This Year’s Enrollment Especially Worth Paying Attention To
Helpful resource: Copper Compression Knee Support Sleeve is a top-rated option for this. (As an Amazon Associate this site earns from qualifying purchases.)
A few things have shifted recently that affect how much this open enrollment window matters for you.
The Inflation Reduction Act’s $2,000 out-of-pocket cap on Part D drug costs, which took effect in 2025, changed the math on prescription drug coverage significantly. If you’re managing multiple medications, the plan that made sense before the cap may not be the best option now that your exposure is capped. Some people who defaulted to more expensive Part D plans “just to be safe” can now find comparable protection at a lower monthly premium.
As of June 2026, the landscape of Medicare Advantage plans has also shifted in several markets. Plan terminations and benefit reductions happened in late 2025, and some beneficiaries were auto-enrolled into different plans without fully realizing it. If you got a notice last fall and didn’t do anything, it’s worth double-checking what you’re actually enrolled in right now before October even arrives. You can verify your current coverage at Medicare.gov or by calling 1-800-MEDICARE.
The Centers for Medicare & Medicaid Services releases the official plan data each fall, typically just before October 15, so the 2027 plan options won’t be visible until the window opens. Don’t try to do serious comparison shopping in September. The numbers won’t be there yet.
How to Use the Enrollment Window Without Wasting It
Medicare Initial Enrollment Period - Sign Up for Medicare at Age 65 · Medicare on Video - Medicare Specialist on YouTube
Here’s what I’d actually walk a family member through:
Before October 15: Gather your current information. That means your list of prescriptions (drug name, dosage, frequency), your preferred pharmacy, and the names of any doctors or specialists you want to keep seeing. Pull your current plan’s Annual Notice of Change (ANOC), which should arrive in late September. Every plan is required to send you one. Read it. I know, it’s not exactly a page-turner, but premium changes, formulary changes, and network changes all live in that document.
October 15 to mid-November: This is your serious comparison window. Use the Medicare Plan Finder tool at Medicare.gov. Enter your drugs and preferred pharmacy and let it do the math on total annual costs across plans in your area, not just monthly premiums. Monthly premiums are the least useful number in isolation. A plan charging $0 per month can cost you far more than one charging $40 if your drugs aren’t covered well.
Worked example: A reader in Ohio was paying $44/month for a Part D plan. His two brand-name medications cost him $280/month in copays. Total annual cost: $3,888. Switching to a plan with a $67/month premium but better formulary coverage on both drugs dropped his copay costs to $95/month combined. New total: $1,944. Same drugs, same pharmacy. Half the cost.
After November 15 through December 7: Make your change. You can make more than one change during AEP and only the last one counts, so if you enroll in a plan October 20th and then find a better one November 8th, switch again. The final enrollment as of December 7th is what sticks.
Don’t wait until the last week of November and assume you have time. December 7th is not a soft deadline.
Medicare Advantage vs. Original Medicare: The Enrollment Decision That Actually Matters
Every AEP is also a chance to reconsider which system you’re in. I have real opinions here.
Medicare Advantage can work beautifully if you’re relatively healthy, you don’t travel much, and you like the lower upfront costs. The extra benefits (dental, vision, hearing) are genuinely useful for many people. But the prior authorization requirements and narrow networks are not a minor inconvenience. For people managing serious or complex conditions, I’ve seen Medicare Advantage become a bureaucratic obstacle course. Prior authorizations delayed, out-of-network specialists inaccessible, claims denied and then partially reversed after appeal.
AARP’s Medicare resource center has solid side-by-side breakdowns if you want to work through the tradeoffs methodically. I’d recommend their comparison tools as a second opinion after Medicare.gov.
Original Medicare with a Medigap supplement and a standalone Part D plan gives you the widest access (any provider in the country who accepts Medicare) and the most predictable costs. It’s typically more expensive monthly. The question is whether the coverage certainty is worth the premium difference for your situation. For people over 75 with multiple conditions, it usually is. For a 66-year-old in good health, the math often goes the other way.
There’s no universally right answer, and anyone who tells you there is isn’t accounting for your actual situation.
Worked example: Margaret, 71, was paying $189/month for a Medigap Plan G and $38/month for a Part D plan. Her Medicare Advantage plan would have been $0/month but had a $3,400 annual out-of-pocket maximum. In two years where she had a minor surgery and a short hospitalization, her Medigap setup saved her roughly $2,100 compared to what she’d have owed under MA. In the two healthy years after that, MA would have saved her roughly $2,700 in premiums. The difference across four years: marginal. The peace of mind in the sick years: not marginal at all.
Sources
- Medicare.gov Plan Finder: Official CMS tool for comparing Medicare Advantage and Part D plans by drug costs, premiums, and network in your zip code.
- Centers for Medicare & Medicaid Services (CMS): Official federal agency overseeing Medicare; publishes enrollment period guidance, plan data, and beneficiary rights.
- AARP Medicare Resource Center: Consumer-facing Medicare guidance including plan comparison tools and enrollment period explainers.
- Medicare & You 2026 Handbook (CMS): The official federal handbook mailed to all Medicare beneficiaries each fall; covers enrollment periods, coverage rules, and rights.
- Kaiser Family Foundation Medicare Policy Research: Ongoing analysis of Medicare Advantage trends, Part D cost data, and enrollment patterns.
This article is for informational purposes only. Medicare rules change annually. Always verify current plan details at Medicare.gov or by calling 1-800-MEDICARE (1-800-633-4227). This site does not sell insurance or recommend specific plans.
Recommended Resources
Disclosure: As an Amazon Associate, we earn a small commission from qualifying purchases at no extra cost to you. We only recommend products that genuinely support the topics covered in this article.
- Medicare For Dummies (~$22), The definitive consumer guide to Medicare, enrollment windows, Part A/B/C/D, and supplement plans.
- Get What’s Yours for Medicare (~$17), Maximize your Medicare benefits and minimize out-of-pocket costs. Covers Part D drug coverage gaps and Medigap in depth.
