Seniors who are eligible for Medicare have several options for getting coverage. They can sign up for original Medicare, which includes Part A hospital coverage, Part B doctor and diagnostic services, and a Part D drug plan. Or they can opt for Part C, otherwise known as Medicare Advantage.

Unlike original Medicare, which has several distinct parts, Medicare Advantage is a one-stop shop for all of your healthcare needs. The good thing about Medicare Advantage is that it's required to offer at least the same amount of coverage as Medicare Parts A and B. Advantage plans also commonly offer coverage for services original Medicare won't pay for, like dental, vision, and hearing. And many Advantage plans offer health coverage overseas -- something original Medicare doesn't do. Plus, with Medicare Advantage, you'll often find that there's a maximum out-of-pocket limit you'll be liable for year after year. Original Medicare doesn't offer that same peace of mind.

A doctor talks to an older man, both smiling, in an office setting.

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That said, if you're not happy with your Medicare Advantage plan, be sure to mark March 31 on your calendar. That's the last day you have this year to drop your current Advantage plan, and if you wait too long, you risk getting stuck with it until 2020.

A new enrollment period

Effective this year, there's a new Medicare Advantage open enrollment period that runs from Jan. 1 through March 31 on an annual basis. This replaces the old Medicare Advantage disenrollment period that previously ran from Jan. 1 through Feb. 14.

What this special period allows you to do is drop the Medicare Advantage plan you're not satisfied with and switch over to original Medicare. At that point, you'll be eligible to sign up for a Part D drug plan, too. Just as importantly, you can also switch from one Medicare Advantage plan to another -- something that was previously only allowed during Medicare's general enrollment period of Oct. 15 though Dec. 7.

One thing you can't do, however, is switch from original Medicare to a Medicare Advantage plan. For that, you'll need to wait until October.

Why might you switch plans? Maybe your Advantage plan's premium costs went up, and you're looking for an option that's more affordable. Or maybe your own health needs changed, and you require a plan that offers better coverage for the medications you take and the services you now use most often.

It always pays to shop around for a more affordable plan, even if you're satisfied with your current one, so use the new Medicare Advantage open enrollment period as an opportunity to do some digging and see if a better option exists for you. Keep in mind that coverage under your plan can change from one year to the next, so if you're inclined to stick with the plan you've had for several years, make sure it covers the services you think it does.

The new Medicare Advantage open enrollment period gives seniors more flexibility when it comes to health coverage. But don't delay -- March 31 will be here before you know it, so if you're inclined to make changes to your Advantage plan, it pays to get moving today.