Medicare Advantage gets a lot of attention. It can be a great fit for some seniors. But the wrong Medicare Advantage plan can also cost you thousands of dollars and lock you into a network of doctors that does not work for you. Here are 10 mistakes that come up over and over.
1. Picking a plan based on TV ads
You have seen them. Celebrities talking about $0 premium plans with dental, vision, hearing, and a grocery card. Those plans exist. But the plan that fits one zip code is rarely the best plan in the next county. The plans on TV are picked by the insurance company's marketing team, not by what fits your situation. The right Medicare Advantage plan for you is decided by your doctors, your prescriptions, your hospital, and your zip code.
2. Not checking if your doctors are in network
Medicare Advantage plans use networks. Your favorite doctor or hospital might not be in the one you pick. Worse, networks change every year. A doctor who is in network this year may be out next year.
Always look up every doctor you see in the plan's online directory before you enroll. Better yet, call the doctor's office and ask whether they take the specific plan you are considering. The doctor and the plan have to agree on a contract; the directory is sometimes out of date. Read more in our guide to keeping your doctor on Medicare.
3. Not checking your prescriptions against the formulary
Each Medicare Advantage plan with drug coverage has a formulary, which is a list of covered drugs. Your medication may be on the list at a high copay tier. It may not be on the list at all. It may require prior authorization or step therapy.
Run your full list of medications through the plan's formulary before you enroll. Total annual drug cost should be a top-3 factor in your decision. For more, see our Part D plan guide.
4. Ignoring the maximum out-of-pocket limit
Every Medicare Advantage plan has a Maximum Out-of-Pocket (MOOP) limit. For 2026, plans can charge up to $9,250 for in-network care, plus more for out-of-network care if the plan is a PPO. That is your downside in a bad year.
People focus on the $0 premium and miss the MOOP. A plan with a $4,500 MOOP can be a much better deal than a plan with a $9,250 MOOP, even if both have the same premium.
5. Switching plans every year without checking networks
Annual Enrollment is the time to review your plan. But people sometimes switch just because a new plan has a small extra benefit, without checking that their doctors are still in the new network. They end up paying out of network rates or losing access to their doctor.
Before you switch, check three things on the new plan: are my doctors in network, are my drugs on the formulary, and is the MOOP comparable.
6. Not understanding prior authorization
Medicare Advantage plans often require prior authorization for things like MRIs, certain surgeries, skilled nursing facility stays, and durable medical equipment. Original Medicare does not require this for most services.
If you have a chronic condition or expect a procedure, ask whether the plan requires prior authorization and how often the plan approves or denies it. A plan with a 90% approval rate is very different from one with a 50% approval rate.
7. Not knowing about the Medicare Advantage trial right
If you joined Medicare Advantage when you first became eligible for Medicare, federal law gives you 12 months to leave. During that trial year, you have a guaranteed right to buy certain Medigap plans without medical underwriting.
This is a one-time protection. Once it is over, switching from Medicare Advantage to a Medigap plan in most states means medical underwriting and possible denial. See our guide on switching back for the full story.
8. Not reading the Annual Notice of Change letter
Every September, your plan sends a letter called the Annual Notice of Change. It explains every change to the plan for the next year. Premiums, copays, networks, the formulary, the MOOP. Most people throw it in the recycling.
That letter is the most important Medicare document you get all year. Read it. Compare the new numbers to the old ones. If the changes do not fit your situation, AEP is your window to switch.
9. Choosing a plan based on extras instead of core benefits
It is easy to be drawn to a plan with a $150 grocery card, free dental cleanings, and a gym membership. Those extras are real. But they should be a tiebreaker between two solid plans, not the main reason you pick a plan.
If a plan has great extras but does not cover your cancer specialist, the extras do not matter. Pick a plan that covers your doctors, your drugs, and protects you from a big-out-of-pocket year. Then look at the extras.
10. Not even considering Medigap as a comparison
Medicare Advantage and Medigap are two very different paths. Medigap pairs with Original Medicare and gives you broader doctor choice, no networks, no prior authorization for most services, and predictable monthly costs. Medicare Advantage usually has lower monthly premiums but more rules and higher max out-of-pocket.
The right answer depends on your situation. People who travel a lot or split time between states usually do better on Medigap. People who want low premiums and live in one place may do better on Medicare Advantage. The mistake is not looking at both before you decide. See our Medicare Advantage vs Medigap comparison for a full side-by-side.
The bottom line
Medicare Advantage is not a bad choice. For many people, it is the right choice. The problem is when people pick a plan without looking at networks, drugs, prior authorization rules, the max out-of-pocket, or the alternative paths. Spending 30 minutes with an independent agent before you sign up can save you thousands and prevent a year of frustration.