Lifestyle

5 Things Medicare Advantage Plans Don’t Tell You at Enrollment

By Erica Coleman · June 15, 2026

Approximately 33 million Americans — more than half of all Medicare beneficiaries — are now enrolled in Medicare Advantage plans offered by private insurers like UnitedHealthcare, Humana, and Aetna. The plans are popular because they bundle hospital, outpatient, and often drug and dental coverage into a single plan, frequently with $0 monthly premiums. What the enrollment materials emphasize less is what the plans limit.

1. Your doctor may not be in the network — and networks change annually

Medicare Advantage plans use provider networks. Unlike Original Medicare, which allows you to see any doctor who accepts Medicare, Advantage plans restrict you to their network — and networks can change every January 1. A doctor who was in-network when you enrolled may leave the network the following year. If your doctor is out of network, you either pay significantly more or switch doctors. Always verify your providers are in-network before each open enrollment period — not just when you first sign up.

2. Prior authorization can delay or deny care

Medicare Advantage plans frequently require prior authorization before covering certain procedures, imaging, specialist visits, and medications. Original Medicare does not. A 2022 HHS Office of Inspector General report found that 13% of prior authorization denials by Medicare Advantage plans were for services that should have been covered — meaning patients were denied care they were entitled to. If a prior authorization is denied, you have the right to appeal. Many denials are reversed on appeal, but the delay can be weeks or months.

3. Out-of-pocket maximums are higher than they appear

Medicare Advantage plans are required to cap annual out-of-pocket costs — but the caps are often $5,000 to $8,500 for in-network care and can reach $10,000 or more for out-of-network services. For a serious illness or hospitalization, those costs add up quickly. By comparison, Original Medicare has no out-of-pocket cap — but Medigap supplemental policies can provide one. The choice between Advantage and Original Medicare with Medigap often comes down to which cost structure better fits your health risk.

4. The $0 premium doesn’t mean $0 cost

The most heavily marketed feature of Medicare Advantage is the $0 or low monthly premium. What that premium doesn’t cover: copays for doctor visits, coinsurance for procedures, deductibles for hospital stays, and cost-sharing for prescription drugs. A $0-premium plan with a $250 hospital copay per day, a $45 specialist visit copay, and a $500 drug deductible can cost significantly more in total annual spending than a plan with a $50 monthly premium and lower cost-sharing. Compare total projected annual cost — not just the premium.

5. Switching back to Original Medicare after the first year comes with a penalty

If you enroll in Medicare Advantage and later decide to switch back to Original Medicare, you may not be able to purchase a Medigap supplemental policy at the same rate — or at all. Most states allow insurers to charge higher premiums or deny Medigap coverage based on health status after your initial enrollment period expires. The practical effect: once you choose Advantage and stay past your first year, switching back becomes financially punishing if you have developed health conditions. This lock-in effect is the single most important thing Medicare Advantage enrollment materials don’t explain clearly.

Medicare’s official plan comparison tool at medicare.gov allows you to compare Advantage, Original Medicare, and Medigap options side by side. Open enrollment runs October 15 through December 7 each year. Use it.