Medicare Advantage vs. Medigap: How the Two Paths Compare
After Original Medicare, retirees face a fork: add a Medigap policy, or swap into a Medicare Advantage plan. The two work very differently on premiums, out-of-pocket risk, doctor choice and the ability to change your mind later. This guide lays out the trade-offs and the enrollment windows that matter.
Original Medicare pays for a lot, but not everything. Part B generally covers about 80% of approved outpatient costs, which leaves a 20% share with no built-in annual ceiling. Most people respond in one of two ways: buy a Medigap policy to fill the holes, or leave Original Medicare for a Medicare Advantage plan that replaces it. The right path depends on your health, budget, doctors and tolerance for risk, and the choice is easier to make than to reverse.
This guide compares the two on the points that matter and explains the enrollment windows. It is general information, not advice, and Medicare rules and plan details change, so confirm specifics at Medicare.gov. For the basics of how Parts A, B and D fit together, start with our overview of Medicare when you retire.
The starting point: what Original Medicare leaves uncovered
Original Medicare, run by the federal government, includes Part A (hospital care) and Part B (medical services). It has real gaps:
- Deductibles for both Part A and Part B
- Coinsurance, including the 20% share of most Part B services
- No annual limit on what you could pay out of pocket
- No drug coverage unless you add Part D
- Little or no routine dental, vision or hearing coverage
You can see a doctor or hospital anywhere in the country that accepts Medicare. Both Medigap and Medicare Advantage are ways to deal with the gaps, but they take opposite approaches.
How Medigap works
Medigap, also called Medicare Supplement Insurance, is sold by private insurers and sits on top of Original Medicare. After Medicare pays its share, a Medigap policy pays some or all of the leftover costs such as coinsurance and deductibles, depending on the plan.
Key features:
- Standardized plans. Policies are identified by letters, and a given letter offers the same core benefits no matter which company sells it. A few states, including Massachusetts, Minnesota and Wisconsin, use their own standardized structures.
- Price is the main difference. Because benefits are standardized, insurers compete mostly on premium and service. Rates for the same plan can vary widely between companies and states.
- Broad provider access. You keep Original Medicare's freedom to see any provider that accepts Medicare, without a network or referrals.
- No drug coverage. You would add a separate Part D plan.
- You pay two premiums. The Medigap premium is in addition to your Part B premium.
The trade-off is a predictable, often higher monthly premium in exchange for lower and more predictable bills when you use care.
How Medicare Advantage works
Medicare Advantage, or Part C, replaces Original Medicare. Private insurers contract with Medicare to deliver your Part A and Part B benefits, usually through a managed-care network such as an HMO or PPO. You still must pay your Part B premium, and you still have Medicare, but the plan handles your claims.
Key features:
- Annual out-of-pocket limit. Advantage plans must cap what you pay for covered in-network services each year, which Original Medicare lacks. The limit is set annually, so check the current figure.
- Often low or zero extra premium. Many plans charge no premium beyond Part B, though copays and coinsurance apply when you use care.
- Bundled extras. Many include Part D drug coverage and some dental, vision, hearing or fitness benefits. Details vary by plan and county.
- Networks and rules. Your choice of doctors and hospitals may be narrower, and some services require prior authorization or a referral. Out-of-network care can cost more or may not be covered, depending on the plan type.
- Plans change every year. Premiums, networks, formularies and benefits can be adjusted each January.
The trade-off is lower upfront cost and extra benefits in exchange for rules about where and how you get care.
Side-by-side comparison
| Feature | Original Medicare + Medigap | Medicare Advantage |
|---|---|---|
| Who runs it | Federal government plus a private supplement | A private insurer under contract with Medicare |
| Monthly cost | Part B premium plus a Medigap premium (often higher) | Part B premium plus a plan premium (often low or zero) |
| Cost when you use care | Usually small and predictable, depending on plan letter | Copays and coinsurance, up to the annual limit |
| Annual out-of-pocket cap | Depends on the Medigap plan chosen | Required for covered in-network care |
| Doctor choice | Any provider that accepts Medicare | Plan network, with out-of-network rules |
| Prior authorization | Rarely required | More common |
| Drug coverage | Separate Part D plan | Often included |
| Extras (dental, vision, hearing) | Not included | Often included in some form |
| Traveling or living in two states | Coverage works nationwide | Depends on the plan; many are local |
| Switching later | May involve health questions for Medigap | Can change plans each year |
The enrollment windows that matter
Timing is where this decision gets expensive if you get it wrong.
Medigap open enrollment
When you are 65 or older and enrolled in Part B, you get a six-month Medigap open enrollment period that starts the month your Part B begins. During that time insurers generally cannot refuse to sell you a policy or charge more because of your health. Outside it, in most states, insurers can ask health questions and may decline or charge more, with some exceptions and state protections.
That asymmetry is the heart of the decision: it is usually easiest to start with Medigap and hardest to come back to it later.
Annual Enrollment Period
Every year from October 15 to December 7, people with Medicare can join, drop or switch Advantage and Part D plans, with new coverage beginning January 1. Plans send notices in the fall that spell out next year's changes, so the notice is worth reading even if you plan to stay.
Medicare Advantage Open Enrollment
People already in an Advantage plan get a separate period early in the year, generally January 1 to March 31, to switch to a different Advantage plan or return to Original Medicare. Check Medicare.gov for the current dates and rules, since special enrollment periods can apply after a move or loss of other coverage.
Costs: look at the whole year
Comparing only the monthly premium misleads. A fuller comparison adds up:
- Premiums: Part B, plus Medigap or any Advantage plan premium
- Expected use of care: office visits, specialists, tests, procedures and drugs
- Worst-case exposure: a hospital stay or serious illness
- Drug costs: whether your medications are on each plan's formulary, and at what tier
- Extras: whether you would actually use bundled dental, vision or hearing benefits
A person who rarely sees a doctor may do fine with a low-premium Advantage plan. Someone who expects heavy use, or who values seeing specialists anywhere in the country without approval, may weigh Medigap's higher premium differently. Both are reasonable positions, not right or wrong answers. High earners should also check how IRMAA income-related premiums change the Part B and Part D costs they pay.
Questions to ask before choosing
- Are my current doctors and hospitals in the plan's network?
- Are my drugs covered, and what will they cost at each stage of coverage?
- What is the plan's out-of-pocket maximum, and does it include drug costs?
- Which services need prior authorization?
- Do I travel often or spend part of the year in another state?
- If my health changes, how easily can I switch?
- How has the plan changed its premiums, networks or drug list since last year?
Where to get unbiased help
Medicare.gov offers a plan finder that lets you compare options by ZIP code and by the drugs you take. Every state also has a State Health Insurance Assistance Program (SHIP), which provides free, unbiased counseling. You can reach 1-800-MEDICARE for general questions. Be cautious with unsolicited calls and mailers, since Medicare plan marketing is heavily regulated but also crowded with lead generators.
Choosing between Medicare Advantage and Medigap is one of the larger health-cost decisions of retirement, and it connects directly to how you plan your budget.
This article is for general information and education only and is not financial, investment, tax, legal or insurance advice. Consider your own circumstances and consult a licensed professional.
Frequently asked questions
Can I have a Medigap policy and a Medicare Advantage plan at the same time?
No. Medigap is designed to fill gaps in Original Medicare, so it does not work with a Medicare Advantage plan, and it is generally illegal for an insurer to sell you one if you are enrolled in Advantage. If you move from Advantage back to Original Medicare, you can look at Medigap again, though you may have to answer health questions.
Do Medigap plans cover prescription drugs?
No. Medigap policies sold today do not include drug coverage, so people with Original Medicare who want it typically add a separate stand-alone Part D plan. Many Medicare Advantage plans bundle drug coverage into the same plan, which is one reason some people find them simpler.
When can I switch between Medicare Advantage and Original Medicare?
The Annual Enrollment Period, which runs from October 15 to December 7 each year, lets most people join, drop or change a plan, with coverage starting January 1. People already in Medicare Advantage also have a separate window early in the year to switch plans or return to Original Medicare. Check Medicare.gov for the current dates and any special enrollment rules that apply to you.
