For starters, because you only get one shot at this, make sure you know what you're signing up for if you choose another plan. That includes ensuring that your medications are covered and that your favorite doctors or other providers are in-network.
Roberts said that even if you see your doctor listed on a plan's online directory, you should confirm that status directly with their office because those listings can be outdated or contain errors.
"When you call your doctor, ask specifically if they are in network for your particular plan," she said. "Don't just say the name of the insurance company."
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If you're planning to drop your Advantage Plan in favor of original Medicare — which consists of Part A hospital coverage and Part B outpatient coverage — you also likely need to get a standalone Part D prescription drug plan. This often was included in your Advantage Plan, and life-long penalties can be applied if you go more than 63 days without coverage.
Additionally, if you're planning to get a supplemental Medicare plan — called Medigap — to pair with original Medicare, be aware of additional rules for applying. These policies help cover costs such as deductibles, co-pays and co-insurance.
When you first enroll in Medicare (typically at age 65), you get six months when you're guaranteed Medigap coverage. That is, you can get a policy without the insurance company nosing through your health history and deciding whether to insure you.