When your parents sign up for Medicare, they’re choosing between two paths: a Medicare Advantage plan, or Original Medicare with a Medigap supplement and a Part D drug plan. Neither is right for everyone. They differ on how much flexibility you get with doctors, how costs are structured and how hard it is to change course later. Here’s how they compare, so you can help your parents ask the right questions.
- Medicare Advantage is an all-in-one private plan, usually with a provider network, prior authorization rules and a yearly out-of-pocket maximum.
- Original Medicare + Medigap + Part D lets you see any provider that accepts Medicare nationwide, with higher monthly premiums but more predictable costs.
- The biggest trap: switching from Medicare Advantage back to Original Medicare later doesn’t guarantee you can buy Medigap. In most states, insurers can use medical underwriting outside protected windows.
- The decision depends on health, budget, doctors, travel and the rules in your parent’s state. Use free SHIP counseling.
The two paths, in one paragraph each
Original Medicare + Medigap + Part D. Original Medicare (Part A for hospital, Part B for medical) is run by the federal government. It covers a lot, but it leaves gaps like deductibles and 20% coinsurance on most Part B services, with no yearly out-of-pocket cap. Medigap is a private supplement policy that fills some or all of those gaps. Since Original Medicare doesn’t include most outpatient prescription drugs, people on this path usually add a separate Part D drug plan. That’s three pieces: Original Medicare, Medigap and Part D.
Medicare Advantage (Part C). Medicare Advantage plans are offered by private insurers approved by Medicare. They replace Original Medicare as the way your parent gets Part A and Part B benefits, and most include drug coverage. Many also offer extras such as some dental, vision or hearing coverage. In exchange, they usually use provider networks and have their own rules for getting care approved.
Side-by-side comparison
| Medicare Advantage | Original Medicare + Medigap + Part D | |
|---|---|---|
| Who runs it | A private insurer approved by Medicare | Federal government (Original Medicare), plus private Medigap and Part D insurers |
| Doctors and hospitals | Usually a network (HMO or PPO). Out-of-network care may cost more or not be covered, except emergencies. | Any provider nationwide that accepts Medicare |
| Referrals and prior authorization | Often required for specialists, procedures and some services | Original Medicare generally doesn’t require referrals or prior authorization for most services |
| Monthly premiums | Often low, sometimes $0 beyond the Part B premium | Part B premium plus Medigap premium plus Part D premium. Usually higher in total. |
| Costs when you get care | Copays and coinsurance that vary by plan and service | Depends on the Medigap plan. Some cover most cost-sharing, so bills are predictable. |
| Yearly out-of-pocket maximum | Yes, for covered Part A and B services. The amount varies by plan. | Original Medicare has none. Medigap fills gaps instead. A few Medigap plans have their own out-of-pocket limits. |
| Prescription drugs | Usually included | Separate Part D plan |
| Extras (dental, vision, hearing) | Often included in some form. Coverage varies widely. | Generally not included. Buy separately if needed. |
| Travel within the U.S. | Coverage outside the plan’s area can be limited, except emergencies | Works with Medicare-accepting providers anywhere in the U.S. |
| Changing your mind later | You can switch during enrollment periods, but getting Medigap later may require medical underwriting | You can switch to Medicare Advantage during enrollment periods |
Exact costs and benefits vary by plan, insurer and ZIP code. Compare real plans in your parent’s area on the Medicare.gov Plan Finder.
Networks and prior authorization: the day-to-day difference
For many families, the most noticeable difference is how getting care works.
With Medicare Advantage, your parent typically picks from doctors and hospitals in the plan’s network. HMO-style plans may require a referral from a primary care doctor to see a specialist. Many services, such as certain imaging, procedures, skilled nursing stays and some drugs, may need prior authorization, meaning the plan has to approve it before it’s covered. Networks can also change from year to year.
With Original Medicare, your parent can generally see any doctor or hospital in the country that accepts Medicare, without referrals. That flexibility matters most for people who travel, split time between states or want access to a specific specialist or academic medical center.
Tip: Before choosing a Medicare Advantage plan, check that your parent’s current doctors, preferred hospital and any specialists they’re likely to need are in network, and ask the plan how prior authorization works for the care they actually use.
How costs are structured
The two paths spread costs differently.
Medicare Advantage tends to have lower monthly premiums, with costs showing up when you use care: copays for visits, coinsurance for some services and costs for hospital stays. The important protection is the plan’s yearly out-of-pocket maximum for covered Part A and Part B services. Once your parent reaches it, the plan pays 100% of covered in-network care for the rest of the year. The amount varies by plan, so check it.
Original Medicare with Medigap usually costs more each month, because your parent pays the Part B premium, a Medigap premium and a Part D premium. In return, depending on the Medigap plan, many medical bills are covered with little or nothing owed at the time of care. That predictability is the main appeal.
A useful way to compare: estimate a normal year and a bad year for each option. A normal year is premiums plus routine costs. A bad year is premiums plus a hospital stay, surgery or a new diagnosis. The one-bad-year stress test is built for exactly this kind of thinking.
The Medigap underwriting trap
This is the part many families learn too late.
When your parent is 65 or older and first enrolls in Part B, they get a 6-month Medigap open enrollment period. During that time, Medigap insurers generally can’t deny them or charge more because of their health.
After that window, in most states, Medigap insurers can use medical underwriting. They can ask health questions and charge more, or decline to sell a policy, based on pre-existing conditions. So if your parent picks Medicare Advantage at 65, then develops a serious condition at 72 and wants to switch to Original Medicare for more flexibility, they can make the switch, but they may not be able to buy a Medigap policy at a reasonable price, or at all.
There are some protections:
- Trial rights. If your parent joined a Medicare Advantage plan when first eligible at 65, or dropped a Medigap policy to try Medicare Advantage for the first time, they generally have about a year to switch back with guaranteed access to Medigap.
- Other guaranteed issue situations, such as a plan leaving the area, may also apply.
- State rules. Some states have extra protections that make it easier to buy Medigap later.
Watch out: The Medicare Advantage Open Enrollment Period (January 1 to March 31) lets your parent drop Medicare Advantage and return to Original Medicare. It doesn’t by itself guarantee access to Medigap. Check with your state’s SHIP or insurance department before your parent leaves a plan.
Questions to help your parents think it through
You’re not choosing for them. These questions help them figure out what matters most:
- Are their current doctors and hospital in the Medicare Advantage networks available to them?
- Do they travel or spend part of the year in another state?
- Do they have chronic conditions or expect significant care in the next few years?
- Would they rather pay more each month for predictable bills, or pay less each month and more when they use care?
- How do they feel about getting referrals and prior authorizations?
- Are their prescriptions well covered by the drug plans available to them?
- If they choose Medicare Advantage now, are they comfortable that buying Medigap later might not be possible in their state?
For more on supporting a parent through this, see our guides to insurance for aging parents and insurance in the sandwich generation.
This primer is general education. For a decision about your parent’s coverage, use free SHIP counseling (find your state at shiphelp.org), 1-800-MEDICARE or a licensed professional.
Frequently asked questions
Can you have Medicare Advantage and Medigap at the same time?
No. Medigap only works with Original Medicare. It can’t pay for costs under a Medicare Advantage plan, so it isn’t something to combine with one. If your parent is switching back to Original Medicare, the timing of buying Medigap matters. A SHIP counselor can walk through it.
Is Medicare Advantage cheaper than Medigap?
Usually on monthly premiums, yes. Total cost depends on how much care your parent uses. In a year with a lot of care, Medicare Advantage copays and coinsurance can add up to the plan’s out-of-pocket maximum.
Can my parent switch from Medicare Advantage to Medigap later?
They can return to Original Medicare during certain enrollment periods. Buying a Medigap policy afterward may require medical underwriting in most states, unless they have a trial right or other guaranteed issue right, or their state offers extra protections.
When is the best time to buy Medigap?
During the 6-month Medigap open enrollment period, which starts when someone is 65 or older and enrolled in Part B. During that window, insurers generally can’t use health status to deny coverage or charge more.
Does Medicare Advantage require prior authorization?
Many plans require it for certain services, procedures and drugs. Rules vary by plan, so ask the plan or check its evidence of coverage document.
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