Overall, while about a third of Medicare recipients have an Advantage Plan and their ranks have been growing, some people discover that their favorite doctor or pharmacy is not part of an Advantage Plan's network and decide to remain on (or return to) original Medicare because their doctor accepts it.
Others, such as frequent travelers, want to avoid the limitations that sometimes come with Advantage Plans, such as requirements to visit in-network doctors or pay more if they are out of network.
Regardless of the reasons for remaining on original Medicare, it's important to understand its limitations.
For instance, Medicare has no out-of-pocket maximum. Additionally, Parts A and B come with deductibles and limitations on what services are covered and to what degree.
Part A hospital inpatient deductible and coinsurance
For 2018, you pay:
$1,340 deductible for each benefit period
Days 1-60: $0 coinsurance for each benefit period
Days 61-90: $335 coinsurance per day of each benefit period
Days 91 and beyond: $670 coinsurance per each "lifetime reserve day" after day 90 for each benefit period (up to 60 days over your lifetime)
Beyond lifetime reserve days: all costs
Part B deductible and coinsurance
$183 per year. After your deductible is met, you typically pay 20 percent of the Medicare-approved amount for most doctor services, outpatient therapy and medical equipment.
"If you're sick a lot, or in and out of doctor's offices, you can end up with some big bills," Gavino said.
That's where Medigap policies help. Yet they aren't a cure-all: For instance, Medicare does not cover dental and vision expenses, and Medigap policies do not pick up those costs. Advantage Plans, on the other hand, might offer coverage for both.
Additionally, many Advantage Plans include prescription drug coverage (Part D). If you are on original Medicare — whether you have a Medigap policy or not — you must sign up for a prescription plan unless you meet certain requirements.
Additionally, depending on a combination of factors — the policy's features, where you live, and sometimes your age — the cost can reach a few hundred dollars a month.