In less than a week, open enrollment will kick off for Medicare participants. To be clear, this period applies to current enrollees who are already on Medicare, not new enrollees.

Those who wish to sign up for the first time can do so on the Social Security Administration's website. And to be clear, it's possible to enroll in Medicare before signing up to receive Social Security benefits.

If you're on Medicare, it's important to make the most of that seven-week open enrollment period. And that also means steering clear of these big mistakes.

Doctor talking to patient.

Image source: Getty Images.

1. Ignoring it entirely

If you're happy with your existing Medicare coverage, then you may decide to opt out of open enrollment. But that could end up costing you big time.

Medicare Advantage and Part D drug plans can change from year to year. If you don't review your options for coverage this year, it could mean missing out on a more cost-effective plan.

2. Not reviewing changes to your existing coverage

Whether you're enrolled in Medicare Advantage or have a Part D drug plan, your plan is required to notify you of any changes it will be implementing for the upcoming year. Neglecting to read through those changes could cause you to make poor decisions when selecting your coverage.

Imagine your current Part D plan is bumping one of your prescriptions into a higher tier, resulting in higher out-of-pocket costs for you. If you don't read up on that change, you might assume that you're best off keeping your existing plan, when in reality, there may be a cheaper plan that categorizes your prescription more favorably.

Furthermore, you may be paying for a Medicare Advantage plan that offers a nice set of supplemental benefits. But if some of those benefits are going away, that higher premium may not be worth it. That's why it's essential that you read up on any changes that are coming down the pike.

3. Not taking medication changes into account

Maybe your Part D plan isn't changing at all. But what if your medications have changed? It could be that you're no longer on the most suitable plan given your specific needs.

If you've changed medications, it's a good time to compare Part D plans and see what coverage they offer. It may be that you'll save money by moving to a different plan.

4. Waiting until the last minute to make changes

The process of comparing Medicare plan choices can be cumbersome. In addition to reviewing different Part D and Advantage plans, you'll also need to assess your coverage as a whole.

If you're enrolled in Medicare Advantage, for example, it may be time to switch over to original Medicare. This especially holds true if you travel a lot and don't like being tied down to a more narrow network of healthcare providers.

Furthermore, if you've made the decision to relocate during the pandemic, then it could be that there's no great Advantage plan choice in your new locale. That would make the case for switching to original Medicare.

Or it may be time to move off original Medicare and onto an Advantage plan. This could make sense if you've been spending a large chunk of your retirement income on non-covered services like dental care and hearing aids.

The point, therefore, is to not leave your research and decision-making to the last minute. Instead, start digging around in mid-October, when open enrollment kicks off.

Medicare open enrollment begins on Oct. 15 and runs until Dec. 7. Be sure to make the most of open enrollment so you can set yourself up with the best coverage going into 2022.