If you're approaching 65, you've probably noticed the mail. Brochures, postcards, and television ads, all promising that one Medicare plan or another is the obvious choice. The decision in front of you, though, isn't really about picking a plan. It's about picking a structure, and the two structures work very differently.
Both can serve people well. The choice between Medigap and Medicare Advantage comes down to which doctors you can see, how care gets approved, what you pay and when, and how easily you can change your mind later. Here is how to compare the two before you choose.
Two Structures, Not Two Versions of the Same Plan
A Medigap policy (also called Medicare Supplement insurance) works alongside Original Medicare. Medicare remains your primary coverage, and depending on the plan letter, a Medigap policy helps pay some or most of the deductibles, copayments, and coinsurance that Original Medicare does not pay.
A Medicare Advantage plan takes a different approach: You receive your Medicare benefits through a Medicare-approved private plan, which typically bundles in drug coverage and extras such as dental or vision.
The two do not work together. You may technically keep an existing Medigap policy after joining Medicare Advantage, but it cannot pay the Advantage plan's deductibles, copays, or premiums, and insurers generally cannot sell you a new Medigap policy while you're enrolled in Medicare Advantage.
The Costs Pull in Opposite Directions
Medicare Advantage front-loads the savings. In 2026, 75% of enrollees in individual Medicare Advantage plans with drug coverage pay no premium beyond the standard Part B premium. In exchange, you pay copays and coinsurance as you use care, up to the plan's annual limit for Part A and Part B services, which averages about $5,400 for in-network services in 2026. Prescription drug spending is subject to a separate Part D limit.
Medigap front-loads the cost. Plan G, the most popular option for new enrollees, averaged about $220 per month nationally at age 65 in MoneyGeek's 2026 analysis of quoted premiums. Actual rates vary by location, insurer, personal characteristics, and the policy's rating method, and premiums may increase over time.
Because Medigap policies sold today do not include prescription drug coverage, you would also typically add a stand-alone Part D plan with its own premium. In exchange, your Part A and Part B cost sharing for covered medical care is generally limited and more predictable, which matters because Original Medicare on its own has no cap on out-of-pocket costs for hospital and physician services.
Networks: How Much Choice You Keep
With Original Medicare plus Medigap, there is generally no network. You can see any doctor or hospital in the country that accepts Medicare and is accepting new patients, without a Medicare-required referral.
Medicare Advantage plans are built around provider networks. For many people, that works fine, and staying in-network is how these plans keep costs down. HMO plans generally require in-network care for routine services, while PPO plans may cover out-of-network care at a higher cost. But the networks are narrower than many enrollees expect. A 2025 KFF analysis using 2022 provider-directory data found that Medicare Advantage enrollees had in-network access, on average, to about half of the physicians available to Original Medicare beneficiaries in their area, and networks can change from year to year.
So the network question is not just whether your doctor is in the plan today. It's also whether the doctors and hospitals you may need will still be there down the road.
Prior Authorization: A Difference Worth Understanding
Original Medicare rarely requires advance approval for care. Nearly all Medicare Advantage enrollees, by contrast, are in plans that require prior authorization for some services, most commonly the expensive ones, such as hospital stays, skilled nursing care, and home health.
Most requests are approved, but the review and appeals process can create paperwork and potentially delay care. Approval practices also vary from one insurer to another, which is one reason two Medicare Advantage plans can offer different experiences of the same benefit.
The Underwriting Window: How Switching Works Later
The rules for changing your mind are different in each direction, and the difference is easy to miss at enrollment.
When you first enroll in Part B at age 65 or later, you get a six-month Medigap Open Enrollment Period. During that period, insurers must sell you any Medigap policy they offer that you are eligible to purchase, regardless of your health history.
If you choose Medicare Advantage instead, federal law provides a limited trial right in two situations: You joined a Medicare Advantage plan when you first became eligible for Medicare at 65, or you dropped a Medigap policy to join Medicare Advantage for the first time. In either case, leaving the plan within 12 months lets you buy a Medigap policy without medical underwriting, though the specific policies available differ between the two situations and application deadlines apply.
After those windows close, the road mostly runs one way. You can move from Medigap to Medicare Advantage during an enrollment period at any point, but moving from Medicare Advantage to Medigap usually requires medical underwriting in most states. An insurer can decline you or charge more based on your health, so for someone whose health has declined, switching back may no longer be a realistic option. Limited guaranteed issue rights do exist, such as when a plan leaves your area, but they are narrow and typically time-limited.
Protections vary by state and change over time, so before enrolling or switching, it is worth confirming Louisiana's current Medigap rules with the Louisiana Senior Health Information Program (LaSHIP), the state's free Medicare counseling service, or with a licensed insurance professional.
What Happens When You Need Care Away From Home
For those of us on the Gulf Coast, this question comes up often. A Medigap policy travels with you: Your benefits are the same with any Medicare-accepting provider in any state. Medicare Advantage plans cover emergency and urgent care anywhere in the country, but routine care generally has to happen within the plan's network and service area. Enrollees who remain outside their plan's service area for more than six months can generally be disenrolled, though some plans offer visitor or traveler programs permitting absences of up to 12 months.
That matters if you split time between states, spend long stretches with children or grandchildren elsewhere, or could find yourself displaced for months after a major storm. It's a scenario Louisiana families know is not hypothetical.
For travel abroad, neither structure provides complete coverage. Dedicated travel medical insurance is worth considering regardless of which route you choose.
Questions to Work Through Before You Decide
There is no one-size-fits-all answer here. If low monthly costs matter most and you're comfortable with a network, Medicare Advantage can be a reasonable fit. If provider flexibility and predictability matter most, the Medigap route is built for that. A few questions can help you find your own answer:
Do you split time between states or travel often? Medigap's lack of networks fits that pattern. Medicare Advantage's service-area rules can complicate it.
Is a specific doctor or health system non-negotiable? With Medigap, any Medicare-accepting provider works. With Medicare Advantage, you would want to confirm they are in-network, knowing that networks can change.
Does a $200-plus monthly premium, plus a Part D plan, fit your retirement budget for decades? If it does, the Medigap route offers more predictable Part A and Part B cost sharing. If it doesn't, Medicare Advantage's lower premiums with usage-based costs may be the more workable structure. (Our blog "How to Determine Living Expenses in Retirement" may help you think through that.)
How would you feel about needing plan approval before a hospital or rehab stay? Some people accept that trade-off for the savings. Others prefer Original Medicare's approach, where prior authorization is rare.
If your health changed in 10 years, would you want the option to switch structures? Moving into Medigap later usually involves medical underwriting, while moving into Medicare Advantage does not. Your answer points to which starting position keeps that option open.
How We Can Help
As fee-only financial advisors, we don't sell insurance, including Medicare plans, so we have no stake in which structure you choose. What we do is help clients evaluate this decision as part of their broader financial plan: modeling premiums against out-of-pocket exposure, thinking through how healthcare costs fit alongside other retirement spending, and coordinating with licensed Medicare professionals when it's time to select a specific plan.
If you're approaching Medicare enrollment, or wondering whether the coverage you chose still fits, we'd be glad to talk it through. Schedule a complimentary call with a fiduciary, fee-only financial advisor.