Do doctors prefer Medicare Supplement or Medicare Advantage?

Many doctors' offices find Original Medicare with a Medigap plan easier to work with, and the reason is paperwork. With Original Medicare, the office bills Medicare directly. There's no plan network, and a Medigap plan pays its share without a referral. Medicare Advantage plans are run by private insurers. Most use networks, and many require prior authorization before tests, surgery or specialist visits. Hospital systems that leave Advantage networks most often cite those denials and slow payment. Original Medicare isn't entirely free of prior authorization, though. Since January 2026, a CMS pilot called WISeR requires prior authorization or a pre-payment review for a short list of services in Arizona, New Jersey, Ohio, Oklahoma, Texas and Washington. Both options cover the same Medicare-approved services. What differs is who approves your care and which doctors you can see.

If you're on an Advantage plan and want any doctor back, timing decides whether you can switch.

• Your plan is leaving your area or ending. Federal law gives you a guaranteed-issue right. A carrier must sell you a Medigap plan with no health questions: Plan G if you became eligible for Medicare in 2020 or later, Plan F if earlier (Plan N isn't covered). You can apply up to 60 days before the old coverage ends and up to 63 days after.
• You joined Advantage when you first got Medicare at 65. You have a 12-month trial right to switch to Original Medicare and Medigap with the same guarantee.
• Neither applies. In most states, the Medigap carrier can ask health questions and decline you. Get approved for the Medigap plan before you drop the Advantage plan, not after.

Several Advantage insurers are leaving markets for 2027. Here's what's changing and what to do if your plan is one of them.