Once you reach 65 years of age, you're eligible to enroll in Medicare. But from there, you have choices. You could stick to original Medicare -- Parts A, B, and a Part D drug plan. Or, you could sign up for a Medicare Advantage plan.

A lot of people are going the latter route these days. The Kaiser Family Foundation reports that enrollment in Medicare Advantage plans has surpassed original Medicare for the first time. But while there are certain, well, advantages of signing up for a Medicare Advantage plan, there are also some major drawbacks you should know about.

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The problem with Medicare Advantage

Seniors are often drawn to Medicare Advantage because these plans commonly offer a wider range of benefits than original Medicare. Original Medicare won't pay for services that include dental care, eye exams, and hearing aids. But it's common for Medicare Advantage plans to include coverage for these necessities.

Another benefit of Medicare Advantage is that under one of these plans, you'll have a cap on your annual spending. With original Medicare, there's no maximum out-of-pocket for the year. However, you may have the option to buy Medigap coverage, or supplemental insurance, to help address that issue.

Despite these perks, Medicare Advantage plans have their share of pitfalls. And a big one that might impact you is that with Medicare Advantage, you're limited to a specific network of providers. This means you may have difficulty securing the care you need, especially if you have a condition that requires you to see specialists often.

Also, just because Medicare Advantage covers certain extra services doesn't mean you'll be approved for them. In fact, Medicare Advantage plans often make it difficult for enrollees to get the authorization they need for different tests and procedures. That delay in essential care could be costly from not just a financial standpoint, but a health-related one, too.

Finally, while Medicare Advantage can be a cost-effective alternative to original Medicare, that's not guaranteed. And if you have a lot of health issues, you may find that Medicare Advantage leaves you on the hook for higher bills.

Think carefully before signing up for Medicare Advantage

You may be tempted to enroll in a Medicare Advantage plan to get additional benefits beyond what original Medicare covers, and also to know that there's a limit on your annual spending. But before you do, think about the drawbacks and research your plan choices carefully.

You may decide that you're better off paying for certain care out of pocket than signing up for Medicare Advantage. And you may also find that with the right Medigap plan, your out-of-pocket costs are more than manageable.

In fact, before you sign up for Medicare Advantage, do a couple of things. First, talk to people you know who are current enrollees and ask about their experience. But also, talk to your trusted providers. Ask how many local plans they're in network with, and ask about their experience with Medicare Advantage from their perspective. You may or may not like what you hear on both accounts, but it's important to have that information either way.