Millions of older Americans get health benefits through Medicare. But coverage under Medicare isn't a one-size-fits-all sort of deal.

As an enrollee in original Medicare, you have the option to choose your own drug coverage. Or, you could sign up for a Medicare Advantage plan for added benefits on top of what original Medicare entails.

You're also not stuck with the Medicare plan you choose for life. Each year during the fall, Medicare participants are able to make changes to their coverage during open enrollment, which runs from Oct. 15 through Dec. 7.

During open enrollment, you can switch Part D plans, move from one Medicare Advantage plan to another or drop Advantage altogether and move over to original Medicare. But to make an informed decision, you need to know what's staying the same with your current Medicare plan and what's changing.

That's why it's so important to review your plan's notice of change carefully. Generally, these notices go out by Sept. 30 so that Medicare enrollees have an opportunity to get updates on their plans in time for open enrollment. If you're new to getting one of these letters, here are some key points to look out for.

1. How your medications are categorized

If you're a Medicare Part D participant, you may be aware that these plans use formularies to group medications into different tiers. These tiers determine your out-of-pocket costs.

One thing you'll want to pay attention to on your notice of change is whether your current prescriptions are moving into a different tier. If one of your medications is bumped into a higher tier, you may be looking at higher costs in 2025. However, it's possible that one of your medications is moving to a lower tier, resulting in less expensive copays for you.

2. How your Medicare Advantage plan benefits are changing

Medicare Advantage plans commonly offer supplemental benefits beyond the scope of what original Medicare covers. It's important to see which of those benefits your plan is keeping in the new year versus taking away.

It may also be that your Medicare Advantage plan is adding benefits for 2025. That's important information to have. But before you get too excited, realize that just because a given Advantage plan offers a certain benefit doesn't mean that it's accessible for all enrollees. If you see new benefits added, inquire to make sure they're options you can take advantage of. You may need a certain diagnosis to use some of your plan's benefits.

3. How your Medicare Advantage plan network is changing

One limitation of Medicare Advantage is that you're generally restricted to a specific network of providers. With original Medicare, you may have more doctors you can see.

Pay attention to changes in your provider network. If your main reason for sticking with your Medicare Advantage plan is to retain access to a certain doctor who will be out of network in 2025, that may be a good reason to switch your coverage.

Whether you're happy with your current Medicare plan or not, it's important to read your notice of change carefully. Doing so could set you up for a successful open enrollment this fall.

The Motley Fool has a disclosure policy.

The Motley Fool is a USA TODAY content partner offering financial news, analysis and commentary designed to help people take control of their financial lives. Its content is produced independently of USA TODAY.

The $22,924 Social Security bonus most retirees completely overlook

Offer from the Motley Fool: If you're like most Americans, you're a few years (or more) behind on your retirement savings. But a handful of little-known "Social Security secrets" could help ensure a boost in your retirement income. For example: one easy trick could pay you as much as $22,924 more... each year! Once you learn how to maximize your Social Security benefits, we think you could retire confidently with the peace of mind we're all after. Simply click here to discover how to learn more about these strategies.

View the "Social Security secrets" »