What Is the Difference Between Medicare Supplement and Medicare Advantage?

When you become eligible for Medicare, you quickly realize that Original Medicare Part A and Part B do not cover everything. You are still on the hook for deductibles, copays, and coinsurance that can add up fast. That is where Medicare Supplement plans (also called Medigap) and Medicare Advantage (Part C) come in. They both help cover those gaps, but they work in completely different ways.

A Medicare Supplement plan works alongside Original Medicare. You keep Medicare as your primary insurance, and the Supplement plan pays some or all of the costs that Medicare leaves behind, depending on the plan letter you choose. A Medicare Advantage plan, on the other hand, replaces Original Medicare entirely. The private insurance company steps in and delivers all of your Part A and Part B benefits, usually bundled with extra benefits like dental, vision, and prescription drug coverage.

That one distinction, working alongside Medicare versus replacing it, drives almost every other difference between the two options.

How the Costs Compare

Cost is usually the first thing people ask about, and the honest answer is that it depends on your situation.

Medicare Advantage plans often have low or even zero monthly premiums. That sounds appealing, especially if you are on a fixed income. However, you will typically pay copays each time you use services, and those costs can vary significantly depending on the plan and the service. Some Advantage plans also have out-of-pocket maximums that can be $5,000, $7,000, or higher before the plan pays 100 percent.

Medicare Supplement plans carry a monthly premium that can range from roughly $80 to $250 or more, depending on your age, gender, location, and the plan letter you choose. In exchange for that premium, your out-of-pocket costs when you actually use healthcare services are much more predictable. Plan G, one of the most popular Supplement plans for new Medicare enrollees, covers nearly everything after the Part B deductible, which is $240 in 2024.

Think of it this way: Advantage plans trade lower monthly costs for higher potential costs when you need care. Supplement plans trade higher monthly costs for lower and more predictable costs when you need care. Neither approach is wrong. It just depends on how you want to budget.

Provider Access and Networks

This is where the two options feel most different in day-to-day life.

With a Medicare Supplement plan, you can see any doctor or specialist in the country who accepts Medicare. There are no networks, no referrals required, and no prior authorization for most services. If your doctor takes Medicare, your Supplement plan works. This matters a great deal if you travel frequently, split time between states, or have a specialist you are not willing to give up.

Medicare Advantage plans almost always use networks. Most are either HMOs, which require you to stay in-network and get referrals to see specialists, or PPOs, which allow out-of-network care at a higher cost. If your preferred doctor is not in the plan's network, you either pay more or find a new doctor. Prior authorization requirements are also common with Advantage plans, meaning the insurance company sometimes has to approve procedures or medications before you receive them.

For people who are generally healthy and do not have complex medical needs, a network may not be a big issue. For people managing chronic conditions or who value the freedom to choose any provider, a Supplement plan often makes more sense.

Prescription Drug Coverage

Medicare Supplement plans do not include prescription drug coverage. If you choose a Supplement plan, you need to purchase a separate Part D plan to cover your medications. Part D plans have their own premiums, deductibles, and formularies, so you will want to check that your specific drugs are covered at a reasonable cost.

Most Medicare Advantage plans include prescription drug coverage built in, often called MAPD plans. This bundling simplifies things for many people. However, drug formularies vary widely between plans, and the tier your medication falls into affects what you pay. It is worth running a drug cost comparison before assuming an Advantage plan's built-in coverage is the best deal for your prescriptions.

Extra Benefits and What They Are Worth

Medicare Advantage plans frequently advertise extra benefits like dental, vision, hearing, gym memberships, and over-the-counter allowances. These benefits are real, but it is worth reading the fine print.

  • Dental coverage through Advantage plans is often limited to preventive care like cleanings and x-rays. Major dental work such as crowns or implants may have very limited coverage or none at all.
  • Vision benefits typically cover one routine exam per year and a basic allowance toward frames or contacts.
  • Hearing benefits vary widely by plan.
  • OTC allowances are often restricted to specific approved items on a plan-approved list.

These extras can be genuinely useful, especially if you do not have other dental or vision coverage. Just do not choose a plan solely for the extras without also evaluating the medical coverage and network.

When You Can Enroll or Change Plans

Timing matters with both options, and the rules are different for each.

With Medicare Supplement plans, the best time to enroll is during your six-month Medigap Open Enrollment Period, which starts the month you turn 65 and are enrolled in Part B. During this window, insurance companies cannot deny you coverage or charge you more because of health conditions. After that window closes, you may be subject to medical underwriting, meaning a health condition could cause a carrier to decline your application or charge a higher rate.

Medicare Advantage has more flexibility. You can switch Advantage plans during the Annual Enrollment Period from October 15 to December 7 each year, and there is also a Medicare Advantage Open Enrollment Period from January 1 to March 31 if you want to switch plans or return to Original Medicare. Switching from an Advantage plan back to a Supplement plan after your initial enrollment window may require medical underwriting in most states, which is something to keep in mind before you try an Advantage plan and then decide you want to switch.

The Bottom Line

There is no universally right answer between Medicare Supplement and Medicare Advantage. If you want provider freedom, predictable costs, and no networks, a Supplement plan is likely the better fit. If you want lower monthly premiums, do not mind a network, and are generally healthy, an Advantage plan could work well and save you money each month.

As an independent agent, I work with multiple carriers on both sides of this decision. I am not pushing you toward any single company or plan. My job is to look at your health situation, your budget, your doctors, and your medications, and help you figure out which option actually makes sense for you. If you are approaching Medicare eligibility or thinking about making a change, reach out to book a free call and we will work through it together.