Once you turn 65, you’re entitled to health coverage through Medicare. But it’s up to you as to whether you want to stick with original Medicare (Parts A and B plus a Part D drug plan) or sign up for a Medicare Advantage plan.

Medicare Advantage plans are offered by private insurers and work similarly to workplace health plans. And for some retirees, they’re a good option. But here are a few problems with Medicare Advantage you should know about before you make the decision to sign up.

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1. Location-based restrictions

With original Medicare, you can generally see any doctor in the U.S. who accepts Medicare as insurance. With Medicare Advantage, you’re limited to a specific network of providers. If you find yourself in another part of the country, you may not have access to providers who are in-network.

The cost of going out of network will depend on your plan. But suffice it to say that going out-of-network could end up being an enormous expense.

2. Prior authorizations

It’s common for Medicare Advantage plans to require prior authorizations for tests or procedures that are out of the ordinary. The reason is that these tests tend to cost insurers more to cover, so you may have to jump through some hoops to get them approved.

The problem, though, is that some Medicare Advantage plans are notoriously difficult about approving care of this nature. This means that certain elements of your care may be delayed — or denied.

The Kaiser Family Foundation found that 99% of Medicare Advantage enrollees are required to obtain prior authorization for one service or another. By contrast, with original Medicare, only a limited number of services require prior authorization.

3. Issues going back to original Medicare

There can be savings associated with Medicare Advantage since these plans commonly offer supplemental benefits beyond what original Medicare covers. And since many Medicare Advantage plans come with a $0 premium (beyond the required premium for Part B), they can be cost-effective for some enrollees.

If you sign up for a Medicare Advantage plan and it doesn’t work out, you’re not necessarily stuck with it forever. Medicare enrollees can make changes to their coverage every year during fall open enrollment, and that includes moving from one Medicare Advantage plan to another or dumping Medicare Advantage altogether.

But moving onto original Medicare isn’t so easy for one big reason — you might struggle to get affordable supplemental insurance known as Medigap. This is often an essential add-on for enrollees in original Medicare since there’s no annual out-of-pocket limit on spending. But once your initial Medigap enrollment window passes, it becomes much harder to get Medigap coverage, which could leave you in a serious lurch.

Some seniors have a perfectly fine experience as Medicare Advantage plan enrollees. And it’s also important to know that, because each plan comes with its own rules, benefits, and costs, your experience on one plan may differ drastically from your experience on another. Either way, it’s important to understand the general pitfalls of Medicare Advantage before you enroll so you don’t wind up regretting your decision.

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