About 13.6 million Medicare beneficiaries were using Medigap policies to reduce their out-of-pocket outlays in 2017. That's about 22.5 percent of the 59 million people on Medicare. These policies can only be used with original Medicare, not Advantage Plans.
While about a third of Medicare recipients (19 million) have an Advantage Plan and their ranks have been growing over time, some people discover that their favorite doctor or pharmacy is not part of the 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, or to get referrals to see specialists.
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If you were planning to drop your Advantage Plan and pair Medigap with original Medicare, you should consider keeping your current coverage unless you know for sure you'll be able to get a policy, Johnson said. Also be aware that underwriting can take a month or more.
Additionally, if you already dropped your Advantage Plan and are uncertain about qualifying for Medigap, you can still switch back before the annual open enrollment period ends Dec. 7.
The Centers for Medicare and Medicaid Services has a chart on its website that shows the differences among Medigap policies. You also can use the agency's search tool to find available plans in your ZIP code. Or, check with your state's Department of Aging (or similar entity) to find out about free counseling for sorting through your options.