When you turn 65 and become eligible for Medicare, you’ll quickly discover that Original Medicare (Parts A and B) leaves some gaps in coverage. Between the 20% coinsurance, deductibles, and no out-of-pocket spending limit, those medical bills can really add up. That’s where your two main options come in: Medicare Supplement Insurance (also called Medigap) or Medicare Advantage plans.

Choosing between these two paths isn’t just about monthly premiums — it’s about your lifestyle, health needs, and what gives you peace of mind. Let’s break down how each option works and what factors should guide your decision.

Understanding Medicare Supplement Insurance

Medicare Supplement Insurance works alongside your Original Medicare coverage to fill in those expensive gaps. Think of it as wraparound coverage that helps pay for things like your Part B coinsurance (that 20% you’d normally owe) and your Part A hospital deductible, which is $1,676 in 2025.

There are currently 10 standardized plans available, labeled A through N (though Plans C and F aren’t available if you became eligible for Medicare after January 1, 2020). The most popular choice is Plan G, which handles nearly everything except the Part B deductible of $257 per year.

What You’ll Pay

Medigap premiums vary significantly based on where you live, your age, and which insurance company you choose. On average, you can expect to pay around $148 per month in 2025, with Plan G averaging about $159 monthly. These premiums can range anywhere from $30 to several hundred dollars per month, so shopping around is essential.

The appeal of Medigap is predictable costs. Once you pay your premium and meet any applicable deductibles, you’ll have minimal additional expenses when you receive care. You can see any doctor who accepts Medicare anywhere in the United States, and there are no network restrictions.

How Medicare Advantage Works

Medicare Advantage plans take a completely different approach. Instead of supplementing Original Medicare, these private insurance plans replace it entirely while still providing all the benefits of Parts A and B. Most also include prescription drug coverage (Part D) bundled into one plan.

The trade-off is that you’re agreeing to use the plan’s network of doctors and hospitals, similar to employer health insurance. If you go outside the network, you’ll typically pay much more — or the services might not be covered at all except in emergencies.

Costs and Benefits

Here’s where Medicare Advantage can be really appealing: 67% of plans charge no premium beyond your required Part B premium of $185 per month. The average premium for all Medicare Advantage enrollees is just $17 per month in 2025.

However, you’ll pay copays and coinsurance each time you use services. What helps is there’s a cap on your out-of-pocket spending — no more than $9,350 for in-network services in 2025. Many plans also include extras like dental, vision, hearing aids, and even gym memberships.

The Doctor Question

One of the biggest differences between these options is provider choice. With Medigap, you keep your Original Medicare and can see any healthcare provider who accepts Medicare. While about 98% of doctors participate in Medicare, around 89% of primary care doctors are currently accepting new Medicare patients. You can travel freely and receive care anywhere without worrying about networks.

Medicare Advantage plans restrict you to their network of providers. While these networks are often quite large, you’ll need to check that your current doctors participate. If you have established relationships with specialists or prefer a particular hospital system, make sure they’re in-network before choosing a Medicare Advantage plan.

Making Your Decision

Consider Medicare Supplement Insurance if you:

Value unlimited provider choice: You want the freedom to see any Medicare-accepting doctor without referrals or network restrictions.

Prefer predictable costs: You’d rather pay higher monthly premiums but have minimal surprise bills when you need care.

Travel frequently: Medigap works the same way whether you’re at home or visiting family across the country.

Have ongoing health conditions: The ability to see specialists without referrals and maintain existing doctor relationships can be invaluable.

Consider Medicare Advantage if you:

Want comprehensive coverage: You like having medical, prescription drug, and often dental/vision coverage all in one plan.

Prefer lower monthly costs: You’re comfortable paying as you go for services rather than higher monthly premiums.

Don’t mind network restrictions: Your preferred doctors are in-network, or you’re willing to switch providers.

Value extra benefits: The included perks like wellness programs, transportation, or over-the-counter allowances appeal to you.

Timing Matters

If you’re new to Medicare, you have a guaranteed right to buy any Medigap policy during your six-month open enrollment period (starting when you first enroll in Part B at age 65). During this window, insurance companies can’t deny you coverage or charge more based on health conditions.

After this period ends, you might face medical underwriting if you want to switch to Medigap later. Medicare Advantage, on the other hand, has open enrollment every fall from October 15 to December 7, making it easier to switch plans or return to Original Medicare.

The Prescription Drug Factor

Remember that Medigap policies don’t include prescription drug benefits. If you choose this route, you’ll need to enroll in a separate Medicare Part D plan to avoid late enrollment penalties. Most Medicare Advantage plans include this protection automatically.

An encouraging development for 2025 is that all Medicare prescription drug coverage now has a $2,000 annual out-of-pocket spending cap, making expensive medications much more affordable regardless of which path you choose.

Your Next Steps

Neither option is inherently better — it depends on what matters most to you. If provider flexibility and predictable costs are priorities, Medigap might be worth the higher premiums. If you want comprehensive benefits at a lower monthly cost and don’t mind network restrictions, Medicare Advantage could be the right fit.

Take time to research plans in your area, check provider networks, and consider your health needs and budget. You can compare options at Medicare.gov or contact your State Health Insurance Assistance Program (SHIP) for free, personalized help.

Key Takeaways

• Medigap supplements Original Medicare while Medicare Advantage replaces it entirely

• Medigap offers unlimited provider choice; Medicare Advantage restricts you to plan networks
• Medicare Advantage typically has lower monthly premiums but higher out-of-pocket costs when you need care

• Both options now include a $2,000 annual cap on prescription drug spending in 2025

• Your initial enrollment period offers the best protections for getting Medigap coverage without medical underwriting