A common assumption is that if you don't touch your Medicare plan, it stays the same. For Medicare Advantage and Part D drug plans, that isn't how it works. Your enrollment carries over. The terms don't necessarily.
Plans are set one year at a time
Medicare Advantage plans and Part D drug plans are offered by private companies that contract with Medicare. Each year, every plan sets its costs and coverage for the coming calendar year. Those terms take effect on January 1 and run through December 31.
So when your plan "renews," you're moved into next year's version of it. Next year's version can look different from this year's.
What can change on January 1
| What can change | What it means for you |
|---|---|
| Monthly premium | What you pay each month just to have the plan |
| Deductibles | How much you pay before the plan starts sharing costs |
| Copays and coinsurance | What you pay per visit, per service or per prescription |
| Drug list (formulary) | Which drugs are covered, and at which tier |
| Provider network | Which doctors and hospitals count as in network |
| Pharmacy network | Which pharmacies are in network or "preferred" |
| Extra benefits | Services beyond Original Medicare that a plan may add, reduce or drop |
Not every plan changes every one of these every year. But any of them can, and the Annual Notice of Change is where the plan has to tell you.
What "doing nothing" actually does
- If your plan continues next year, you stay enrolled automatically, under next year's terms.
- If your plan is not continuing in your area, it has to send you a separate notice explaining your options. Read that one carefully, and don't assume you'll simply be carried over.
Doing nothing is a perfectly reasonable choice when next year's terms still fit you. The point is to make it a choice rather than a default.
What doesn't change this way
Original Medicare — Part A and Part B — isn't a private plan with its own annual contract. Its coverage rules and costs are set nationally and can be adjusted each year too, but you won't get an Annual Notice of Change for it. Supplement (Medigap) policies work differently again: they don't use the fall review period the same way. Our guide to the four parts of Medicare explains how these pieces fit together.
The practical takeaway: once a year, between October 15 and December 7, it's worth spending a few minutes confirming that next year's version of your plan still covers your drugs, your doctors and your pharmacy.
Free printable
The annual review checklist
Seven things to check before December 7, in the order they appear in your plan's letter. The email version is coming soon.