Once you're enrolled in Medicare, it's easy to assume that's the end of the decisions. You picked a plan, it's working, and renewal happens automatically each year. But "automatic renewal" doesn't mean "unchanged." Every fall, your plan can quietly reset its costs, its drug list, and its network — and your own health and prescriptions change too. A short annual review makes sure the plan you have still fits the person you are now, before the changes lock in for another year.

Your plan can change every year — even if you don't

This is the heart of it: each year, Medicare Advantage and Part D drug plans are allowed to change their premiums, deductibles, copays, the list of drugs they cover (the formulary), and which doctors and pharmacies are in-network. Those changes take effect January 1, whether or not you do anything. The plan that was the perfect fit when you enrolled can drift into a poor fit — not because anyone did anything wrong, but because both sides of the equation moved.

The letter in your mailbox: your Annual Notice of Change

By the end of September, your plan mails you an Annual Notice of Change (ANOC). It's the document that tells you exactly what's changing in January — your premium, your deductible, your copays, any drugs moving to a higher tier or off the list, and any network changes. It often arrives in a thick envelope and goes straight to the recycling. Don't toss it. You don't have to read every page; just look for the handful of lines that affect your doctors, your drugs, and your costs.

The two windows you can use

There are two times of year you can make changes, and they're not the same:

• October 15 – December 7 (Medicare Open Enrollment): the main window. Anyone with Medicare can switch Medicare Advantage plans, change or add a drug plan, or move between Original Medicare and Medicare Advantage. Changes take effect January 1.
• January 1 – March 31 (Medicare Advantage Open Enrollment): a narrower backup, only for people already in a Medicare Advantage plan. You get one change — switch to a different Advantage plan, or drop back to Original Medicare (and add a drug plan). You can't use it to jump from Original Medicare into Advantage, or to change a standalone drug plan.

A 6-point annual review

Whether you do this yourself or with help, these are the things worth checking each fall:

• Your doctors and hospitals — are they still in your plan's network for next year?
• Your prescriptions — is each drug still covered, and at what tier? Watch for new restrictions like prior authorization.
• Your pharmacy — is it still preferred or in-network?
• Your total expected cost — premium plus the out-of-pocket you'd actually pay for the care and drugs you use.
• The plan's quality (star) rating — a quick signal of service and performance.
• Extra benefits — dental, vision, hearing, or other perks that may have been added or dropped.

Review them differently: Original Medicare + Medigap vs. Medicare Advantage

How you review depends on how your coverage is built. If you're on a Medicare Advantage plan, the annual review is mostly about that plan's changing costs, drugs, and network. If you have Original Medicare with a Medigap (supplement) and a standalone drug plan, your Medigap coverage is generally stable, so the review focuses on your Part D drug plan, which can change every year.

One important, durable caveat if you're ever tempted to switch from Medicare Advantage to a Medigap policy later: outside of your initial protected window at 65, Medigap insurers in most states can use medical underwriting — meaning they can charge more or decline you based on your health. A few states have added limited windows that work differently, and those rules change from time to time. Before assuming you can switch back, it's worth confirming the current rules in your state rather than counting on it.

Free, unbiased help — wherever you live

You don't have to sort this out alone or under pressure. Your state's State Health Insurance Assistance Program (SHIP) offers free, unbiased Medicare counseling and can run your drugs and doctors through the official Medicare Plan Finder with you — find yours at shiphelp.org or 1-877-839-2675. You can also compare plans yourself at Medicare.gov. And if you'd like someone to sit down and review it together each fall, that's a standing part of what we do for our clients — no cost, no pressure.

This article is educational and reflects general rules drawn from Medicare.gov and CMS.gov. Enrollment dates and rules can change, and individual situations vary — please confirm details for your circumstances. It is not a recommendation of a specific plan. Last reviewed: June 2026.