You’ve signed up for Medicare Parts A and B—but is Original Medicare enough to protect you from surprise bills? Usually not. That’s why many people add a Medigap plan to cover what Medicare doesn’t and a Part D plan for prescription drugs. Here’s why relying on Original Medicare alone can leave you with bigger bills than expected—and how Medigap can close those gaps.

Is Original Medicare Enough? The 20% Coinsurance Problem Explained

When you turn 65, getting your Medicare card feels like a huge relief — until you start hearing about gaps, deductibles, and the unlimited 20% Medicare doesn’t pay. It’s natural to wonder: Is Original Medicare enough? The short answer is no — but the reason why matters even more.

Original Medicare (Parts A and B) was never meant to cover 100% of your healthcare costs. It’s designed to handle most of the bill, leaving you responsible for the rest — the copays, deductibles, and that 20% coinsurance with no annual cap. And that open-ended 20% can turn into a serious financial hit if you ever face surgery, hospitalizations, or ongoing treatment. (Source: Medicare.gov)

Let’s say you need outpatient surgery costing $10,000: Medicare pays $8,000 and you pay $2,000 out of pocket. Repeat that a few times a year, and you’ll see why very few people rely on Original Medicare alone. Unpaid medical bills are the number one reason for bankruptcy filing for American’s over 65…and nearly all those people who went bankrupt were on Medicare.

👉New to Medicare and not sure where to begin? Beginner’s Guide (plain English, quick read).

Who Can Afford to Only Have Original Medicare? (The Exceptions)

If you stick with Original Medicare alone, you’re essentially self-insuring against major medical bills. Given today’s healthcare costs, that’s a risky move unless you fall into one of a few exceptions:

1. You Have Robust Employer or Union Coverage

This group is the most common exception. If you’re still working or retired with a robust employer or union plan, it likely acts as your supplement and covers that 20% gap.

2. You Qualify for Medicaid

If you have Dual Eligibility (Medicare + Medicaid), the program pays nearly all your remaining premiums, deductibles, and coinsurance. That extra government layer makes Medigap unnecessary.

3. You Have Significant Financial Reserves

Some skip supplemental coverage because they can afford to — usually those with millions saved who can easily absorb a $20,000 to $100,000 bill in a year. For everyone else, that’s an unacceptable gamble.

4. You are a Veteran with VA coverage

If you rely almost entirely on VA facilities and understand how VA and Medicare coordinate, you might go without Medigap — just remember check with the VA if this would work for your situation.

If you don’t fit snugly into one of these four categories, protecting yourself from the unlimited 20% should be your top priority. So, who actually sticks with Original Medicare alone? The truth is, very few do—and most who try end up adding Medigap once they see the real costs.

Why Many People Add Medigap to Original Medicare

When people realize the massive financial risk associated with Original Medicare Only, most decide to add coverage. For those who want the simplest, safest protection, Medigap (Medicare Supplement Insurance) is the top choice. It’s designed to fill the gaps Original Medicare leaves behind — especially the 20% coinsurance.

Think of the “why” in terms of control and peace of mind:

  • Financial Certainty: Medigap plans (especially Plan G) cover almost every deductible and copay that Original Medicare leaves behind. That means predictable monthly bills and no surprise medical debt. See real Medigap prices in your ZIP— Get an Instant Medigap Quote.
  • Zero Networks, Total Freedom of Choice: Medigap works everywhere in the country that accepts Medicare. No networks, no referrals, no headaches. If a doctor takes Medicare, they take your Medigap plan too.
  • Peace of Mind: For the cost of a fixed monthly premium, you virtually eliminate the risk of facing bills that could wipe out your retirement savings.
  • Easy billing. Medicare pays first; your Medigap typically pays its share automatically. No claim forms, no waiting.
  • Travel Benefits. Many top plans (like G and N) include Foreign Travel Emergency coverage — perfect for cruises or trips abroad.

Simply put, most people add Medigap because they want to use their Medicare benefits with confidence, knowing their financial exposure is essentially eliminated.

👉 New to Medigap? Don’t guess—read our Beginner’s Guide.

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What Happens if I Get Sick with Only Original Medicare?

Picture Eleanor, 68. After a few specialist visits, an MRI, and weeks of physical therapy, the bills start stacking up. Medicare pays its share, but there’s no annual cap on what she owes for many Part B services.

Here’s what happens when you rely only on Original Medicare:

  • You owe the Part A hospital deductible ($1,676 ) each benefit period.
  • You may face excess charges if your doctor bills above Medicare’s approved amount.
  • You pay 20% of every outpatient service, with no maximum limit.
  • You get no help with foreign emergency care.
  • You have no drug coverage unless you added Part D.

Now imagine that same year with Medigap in place: Medicare pays first, then Medigap quietly covers the rest. Eleanor can focus on recovery instead of bills.

💡 In short: getting sick with only Original Medicare can drain your savings fast. One tough year can turn into a lifetime of medical debt.

👉 Want protection from surprise bills? Compare Medigap plans or get a free quote—we’ll help you find peace of mind.

Can You Just Add Part D to Original Medicare and Be Covered?

Some people think that adding a Part D drug plan to Original Medicare is enough coverage. But let’s be clear: Part D only covers prescription drugs. Part D helps with medications only — it doesn’t touch your medical bills.

That means “Original Medicare + Part D” still leaves you fully responsible for:

  • The 20% coinsurance for outpatient care
  • Hospital deductibles
  • Skilled nursing copays
  • Excess charges from doctors

💡 Part D is essential for prescriptions, but it won’t protect you from medical costs. That’s why most people add Medigap to cover what Medicare leaves behind.

Medigap vs Medicare Advantage: Pros, Cons, and Who Should Choose Which

Once you realize that Original Medicare alone isn’t enough, your decision comes down to two paths for complete coverage: Medigap or Medicare Advantage (MA). Both fill the gaps — but in very different ways. Here’s a side-by-side look:

Feature Medigap (Medicare Supplement) Medicare Advantage (Part C)
How it Works Secondary insurance you buy from a private insurer that helps pay the share Original Medicare doesn’t—typically the remaining ~20% Part B coinsurance (plus other cost-sharing depending on plan letter) after Medicare pays its portion. Alternative way to receive Medicare: your Part A & B benefits are delivered through a private HMO/PPO plan instead of Original Medicare.
Out-of-Pocket Risk Very low. After the Part B annual deductible, most Medicare-approved costs are covered with plans like G; exposure varies by plan letter. Moderate. You pay copays/coinsurance as you use care, but there’s a plan-set annual out-of-pocket maximum.
Doctor Network No network. See any doctor in the U.S. who accepts Medicare; if they take Medicare, they take your Medigap. Not cover additional benefits like dental or vision care. Restricted. Must use the plan’s HMO/PPO network (out-of-network rules vary by plan). Also include dental, vision and hearing care.
Monthly Cost Requires a separate Medigap premium (in addition to your Part B premium). Often $0 or low premium, but costs apply when you use services (until you hit the plan’s OOP max).
Ideal For People who value freedom, predictability, and minimal out-of-pocket surprises. Also, many plans include limited foreign travel emergency. People who prefer lower monthly premiums and don’t mind copays or staying in a network.

Who typically chooses which?

  • Want any-doctor access and steady bills? → Go with Medigap.
  • Prefer lower or $0 premium and don’t mind networks/authorizations? → MA can fit—just review your doctors and meds every AEP.

📌 Want to see which fits your lifestyle? Use our Medigap Plan Finder Wizard or get a free quote in minutes.

Real Costs by Plan Letter: Plan G vs Plan N vs High-Deductible G

If you’ve decided that Original Medicare alone is too risky (which it is!) and Medigap is your path forward, the next step is simple — choose your plan letter. The most popular options—Plan G, Plan N, and High-Deductible Plan G—balance protection and price in slightly different ways:

Plan Coverage Feature How You Pay the Difference
Plan G (The Top Tier) Covers nearly all Medicare-approved costs that Original Medicare leaves you to pay. You pay the annual Part B deductible; after that, most Medicare-approved costs are typically $0.
Plan N (The Balance) Covers most costs similar to Plan G. You pay the Part B deductible plus small copays (up to $20 for office visits; up to $50 for ER if not admitted). Note: does not cover Part B excess charges, but they are rare.
High-Deductible G (HD-G) Same benefits as Plan G after you meet a high annual deductible. You pay Medicare cost-sharing until you meet the plan’s high annual deductible ($2,870), then it works like Plan G.

💡Still have questions? Check out our full article for more details: “Medigap Plan G vs. Plan N: How to Choose the Right Plan for Your Needs“.

👉 Want to compare real prices in your area? Use our Medigap Quote Tool or call us today—we’ll help you find the right fit.

Enrollment Windows: When to Add Medigap If You Keep Original Medicare

Timing is your best friend here—it’s the difference between the easy button and medical underwriting:

  • Your golden window: Your Medigap Open Enrollment Period (OEP) starts the month you turn 65 and enroll in Medicare Part B. It lasts six months, and during that time you can’t be denied coverage or charged more for health reasons. If you can, grab your Medigap here.
  • After the window: Once it closes, most insurers can ask medical questions (underwriting). Many people are still approved, but some may pay more — or get declined. Don’t guess — check your odds instantly with our Medigap Underwriting Checker.
  • Guaranteed-Issue (GI) events: Certain life events create a no-underwriting path (e.g., losing employer coverage, moving out of your MA service area, plan termination). Details vary—ask us to translate your situation into plain English.
  • State rules that help:
    • Birthday Rule (CA, OR, IL, and now many other states.): around your birthday, switch to equal or lesser benefits without underwriting.
    • Anniversary Rule (MO): switch carriers for the same plan once a year without underwriting.
    • Year-round GI (CT, NY): enroll/switch anytime with no health questions.

👉 Too much info to track? Call 800-930-7956 and we’ll help you decide. Our help is 100% free for you.

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Common Mistakes with Original Medicare Only (and How to Avoid Them)

Let’s skip the “wish-I’d-known” moments. Many people assume Medicare covers everything—but that’s rarely true. Here are the most common mistakes people make when they rely on Original Medicare alone (and how to avoid them):

  • Stopping at Original + Part D: Part D covers drugs only. It doesn’t pay your hospital or doctor bills. Add Medigap for predictable medical costs.
  • Assuming “I’m healthy; I’ll buy Medigap later“: Health can change—and later may mean underwriting. If you have a pre-existing condition later you may be turned down for Medigap. If you’re eligible now, use your Open Enrollment. Get your Medigap Quote here.
  • Assuming Medicare covers dental, vision, or hearing: it doesn’t. You’ll need stand-alone coverage.
  • Forgetting foreign travel limits: Original Medicare has very limited coverage abroad; many Medigap letters include limited Foreign Travel Emergency (FT&E)—handy for cruises/trips. Need more cushion for international care? Consider IMG for higher limits.
  • Letting a missing Medicare card delay care: Providers can usually verify eligibility electronically; don’t skip needed care.

FAQs: Is Original Medicare Enough Without Medigap or MA?

Q: Does Medigap change which doctors I can see?
A: Not at all. If a provider accepts Medicare, they automatically accept your Medigap plan—no matter which company you choose.

Q: Can I just add Part D and skip Medigap or Medicare Advantage?
A: Yes but Part D only covers prescriptions. It doesn’t help with hospital bills or your 20% coinsurance for outpatient care. That’s why many people combine Original Medicare + Medigap + Part D for full protection.

Q: Can I drop Medigap later?
A: Yes, you can—but be careful. If you try to re-enroll after your Open Enrollment Period, you might face medical underwriting or higher premiums. Always check your state’s guaranteed-issue rules before dropping coverage.

💡 Still unsure what’s right for you? Real experiences matter: read “Is Medigap Worth It? 93% Say Yes” to see how other seniors made their choice.

How to Choose the Right Coverage Beyond Original Medicare

By now, the answer to Is Original Medicare enough? should be crystal clear: it’s a solid foundation, but it’s not a complete financial shield. So, let’s make this simple. Use this 3-step playbook and be done with it.

First Step: Pick your path (freedom vs framework)

Second Step: If you choose Medigap, pick the letter

  • Plan G = “sleep-well” option. Pay the small Part B deductible, then nearly everything is covered.
  • Plan N = lower monthly premium with small copays; no Part B excess-charge coverage (but those are rare).
  • High-Deductible G = lowest premium with a bigger annual deductible; good if you’re healthy and want a safety net.

Tip: Same letter = same benefits across companies. Shop price, pricing method, discounts, and rate history. Compare Medigap Plans Here.

Last Step: Add the right extras.

Reality checks that save money:

  • Timing matters. If you’re 65+ and starting Part B, use your 6-month Open Enrollment to skip underwriting. Missed it? Ask about GI events and state rules (Birthday/Anniversary/Year-round GI) before applying.
  • Don’t overthink carriers. Focus on price for the same letter, plus discounts (household, autopay, annual, new-to-Medicare).
  • Re-shop occasionally. Rates change; your doctors and meds might, too.

💡 In short: Medicare is your foundation; Medigap makes it complete.
Call 800-930-7956 or get an Instant Quote to protect yourself from the 20% gap—with zero pressure and clear answers.