If you have a Medicare drug plan, here’s the direct answer: yes, it can change every year, even if you never touch it — the cost, the list of covered drugs, and the pharmacy network can all look different on January 1 than they did the year before. The plan that worked well last year isn’t guaranteed to work well next year. That’s exactly why Medicare requires plans to send you a notice each fall telling you what’s different, and it’s worth more than a glance.
- Medicare drug plans are required to mail an Annual Notice of Change (ANOC) by September 30, explaining what changes January 1.
- Costs, the drug list (formulary), and the pharmacy network can all shift year to year — a plan doesn't have to change its name for your coverage to change.
- The Annual Enrollment Period (AEP), October 15 – December 7, is when you can join, switch, or drop a standalone Part D plan for the coming year.
- Going 63 days or more without Part D or other creditable drug coverage can trigger a late-enrollment penalty that generally stays as long as you have Part D.
The letter that’s easy to set aside
Every fall, Medicare drug plans and Medicare Advantage plans must send members an Annual Notice of Change by September 30. It’s not junk mail. It summarizes the changes taking effect in January; keep the accompanying plan materials handy when you need the fuller coverage and cost details.
The trouble is that it doesn’t always look urgent. It’s dense, it arrives alongside a lot of other mail, and if nothing about your health changed, it’s tempting to assume nothing about your coverage did either. That assumption can leave you unprepared for changes to your drug coverage.
What can actually change, year to year
A plan can change more than its premium. Here are items to check:
| What to check | Why it matters |
|---|---|
| Monthly premium & deductible | These may change for the coming year. |
| Formulary (drug list) & tiers | A drug you take could move to a different tier, require prior authorization, or no longer appear on the list. |
| Pharmacy network | Check whether your regular pharmacy’s participation or preferred status has changed. |
| Coverage rules | Check for quantity limits, step therapy, or prior authorization requirements that apply to your medications. |
Formulary changes can catch people off guard because a drug may still be covered but at a different out-of-pocket cost or with a new coverage rule. Reviewing your own medication list against the notice, rather than assuming “covered” means “covered the same way,” can help you spot those changes before the new plan year begins.
Why this check matters every single year
Medicare requires the ANOC every fall, and formularies can change from one year to the next — that alone is reason enough to look. The useful question is not whether last year’s coverage worked, but whether next year’s formulary and rules still fit the medications you take.
When you can actually act on it
If you have a standalone Part D plan, the Annual Enrollment Period — AEP — runs October 15 through December 7 every year. Any change you make takes effect January 1. It’s worth naming that one plainly, because Medicare also has a separate Medicare Advantage Open Enrollment Period running January 1 through March 31, and the Marketplace has its own Open Enrollment on different dates again. AEP is not Part D only — it’s also when someone with Medicare Advantage can make coverage changes; the January window is an extra, narrower one for people already in an Advantage plan. AEP is the one this notice is preparing you for. That’s the window where the ANOC actually becomes useful: your notice typically arrives before the window even opens, which gives you real time to compare your options before AEP closes rather than scrambling in the final days.
If you’re enrolled in a Medicare Advantage plan rather than a standalone Part D plan, AEP still applies to you, and you may also have the January 1 – March 31 window — the rules for what each one lets you change differ, and that’s covered in more depth in our guide to changing Medicare plans. This post is specifically about the annual review habit, not a comparison of enrollment windows.
One rule worth keeping in mind regardless of timing: a late-enrollment penalty can apply if you go 63 days or more without Part D coverage or other creditable prescription drug coverage. It’s generally added to your premium and stays for as long as you have Part D — one more reason to review before a window closes rather than after.
A pattern I see every fall
I hear a version of this every year around this time: someone assumes their drug coverage is “set” because nothing about their health changed, then finds out in January that a maintenance medication moved to a higher tier or their usual pharmacy is no longer preferred. It’s rarely a dramatic mistake — usually just an envelope that got set aside during a busy September. The fix isn’t complicated, just consistent: open the notice, check it against your actual medication list, and use the full AEP window rather than waiting until the final days to make a change if you need one.
What to actually do this fall
- Watch for your Annual Notice of Change in September, and read the section on your specific drugs, not just the summary.
- Compare your current medications against next year’s formulary and tiers — not just whether a drug is “covered,” but at what cost and under what rules.
- Confirm your regular pharmacy is still in-network, and still preferred if that matters to your copay.
- Mark October 15 – December 7 on your calendar if a change turns out to be worth making.
- If you’re unsure whether your plan is standalone Part D or Medicare Advantage, that distinction decides which rules apply to you — our Medicare Advantage vs. Medicare Supplement post walks through the difference.
This is one of those Medicare habits worth making routine. I work with multiple carriers across North Carolina and the other states I’m licensed in, and if you’d like help thinking through your notice once it arrives, book a call or visit our Medicare page for the broader picture — including our turning-65 checklist if you’re newer to all of this.
(This is program-level educational information, not a comparison of specific plans, carriers, or benefit amounts.)
