Do I Really Need Supplemental Insurance With Medicare?
No, you aren't required to buy supplemental insurance with Original Medicare.
But Original Medicare has no yearly limit on what you can owe for covered care, so whether you need extra coverage depends on what you already have and how much risk you can absorb.
It's one of the first questions I hear from people new to Medicare, so here's how I walk clients through it.
Quick Answer
If Original Medicare is your only coverage, you're exposed to deductibles and 20% coinsurance with no annual cap.
If you already have Medicaid, TRICARE For Life, or solid retiree coverage, a separate Medigap policy may be redundant.
If you have none of those, Medigap is usually worth pricing out, and the best time to buy is your first six months on Part B.
In This Article
Is Supplemental Insurance Required With Original Medicare?
No. Medicare Parts A and B work on their own, and no law requires you to add anything.
Most people do add something, though.
KFF's analysis of 2023 federal survey data found that 87% of people in traditional Medicare had some form of additional coverage: Medigap (43%), employer or retiree coverage (29%), Medicaid (14%), or another source.
That leaves about 3.5 million people in traditional Medicare with no supplemental coverage at all.
It's also worth clearing up one common mix-up: Medicare Advantage isn't supplemental insurance. It's a different way to receive your Medicare benefits, and you can't pair it with a Medigap policy.
What Could You Pay Without Supplemental Coverage?
Original Medicare pays most of the bill for covered Part A and Part B care, but it leaves you responsible for the rest.
Here's what that could look like in a hypothetical bad year, using 2026 cost-sharing amounts and Medicare-approved charges.
This is an illustration of the risk, not an estimate of what a typical person spends in a year.
| What happens | Your share with Original Medicare only |
|---|---|
| Hospital stay in March (Part A deductible) | $1,736 |
| Second hospital stay in October, after a new benefit period begins | $1,736 |
| Part B annual deductible | $283 |
| 20% of $40,000 in Medicare-approved outpatient charges after the Part B deductible (specialists, imaging, infusions) | $8,000 |
| Total out of pocket | $11,755 |
Illustrative example. Deductible amounts are 2026 figures from Medicare.gov; CMS typically announces the following year's amounts in November. Does not include premiums, longer hospital stays, skilled nursing coinsurance, or Part B excess charges.
The number itself isn't the scariest part.
The scariest part is that there's no ceiling. If that $40,000 in outpatient care were $150,000, your 20% share would be $30,000.
For comparison, on those same Medicare-covered services, someone enrolled in standard Plan G would have owed only the $283 Part B deductible in Medicare cost-sharing.
Someone with High-Deductible Plan G would have paid Medicare's cost-sharing until reaching the plan's 2026 deductible, and the policy would have paid its covered share after that.
The High-Deductible Plan G deductible is $2,950 in 2026 and increases to $3,050 in 2027.
Either way, Medigap premiums and anything Medicare doesn't cover would be separate costs.
What Medigap Doesn't Cover Either
Medigap pays your share of Medicare-approved costs. It doesn't add new benefits. Even with a Medigap policy, you'd still need separate coverage or savings for:
- Prescription drugs (that's Part D)
- Routine dental, vision, and hearing aids
- Long-term custodial care
If you want the full rundown of how these policies work, see What Is Medicare Supplement Insurance?
When You May Not Need a Medigap Policy
Plenty of people already have coverage that does the same job, and buying Medigap on top of it can mean paying twice for the same protection.
| Your situation | What to consider |
|---|---|
| You only have Original Medicare | You have no annual out-of-pocket limit on covered Part A and B services. This is the situation supplemental coverage exists for. |
| You have full Medicaid | Medicaid generally helps with Medicare cost-sharing, and Medicare.gov notes it's illegal to sell you a Medigap policy if you have Medicaid, except in certain situations. |
| You qualify for the QMB program | This Medicare Savings Program helps pay Part A and B premiums, deductibles, and coinsurance. |
| You have retiree coverage from a former employer or union | It usually pays after Medicare. Compare what it covers and costs before adding Medigap, and ask what happens if the employer changes the plan. |
| You're still working with employer coverage | Depending on employer size, your group plan may pay first (see how Medicare works with employer coverage). Many people delay Part B, which also delays their Medigap Open Enrollment Period. |
| You have TRICARE For Life | TRICARE For Life generally acts as second payer after Medicare, so most people with it don't need Medigap. |
| You've chosen Medicare Advantage | Medicare Advantage is a different way to receive Medicare benefits. You can't use Medigap to supplement a Medicare Advantage plan. |
If you see yourself in rows two through six, your first step isn't shopping for Medigap.
It's finding out exactly how your existing coverage works with Medicare, because that answer may make Medigap unnecessary.
What I See Most Often
One mistake I've encountered is people buying Medigap without checking whether their retiree insurance already pays Medicare's remaining deductibles and coinsurance.
I've also seen the opposite: someone keeps expensive retiree coverage without comparing its benefits against Medigap.
Before making a change, I recommend reviewing both the monthly premiums and how each policy pays after Medicare.
When Medigap Is Usually Worth Considering
If Original Medicare would be your only coverage, Medigap tends to make the most sense when one or more of these apply:
- A big medical bill would hurt your savings. Medigap can substantially reduce your exposure to Medicare's deductibles and coinsurance in exchange for a monthly premium.
- You want to budget your healthcare costs. With Plan G, your main out-of-pocket cost beyond premiums is the Part B deductible.
- You want to see any doctor who accepts Medicare. There are no networks, which matters for people who travel or split time between states.
- You have ongoing health conditions. Frequent specialist visits and treatments add up quickly at 20%.
- You can comfortably afford the premium. A policy you'll drop in two years doesn't protect you much.
The trade-off is real: you pay a premium every month whether you use care or not. To see what that typically costs, start with our guide to average Medigap premiums.
If Medigap sounds like a fit, the next step is seeing what it would actually cost where you live.
The Part of This Decision That's Hard to Undo
Here's the detail that changes how I'd approach this question.
Your Medigap Open Enrollment Period lasts six months, starting the month you're 65 or older and enrolled in Part B.
During that window, companies can't turn you down or charge you more because of your health.
After it ends, most states let insurers ask health questions and decline your application (more on buying a Medigap plan later). There are exceptions, including certain guaranteed issue rights and broader rules in a handful of states such as New York and Connecticut.
So "going without for now" isn't always a choice you can reverse later. The people who regret skipping Medigap are usually the ones whose health changed before they tried to buy it.
One thing I'd watch: if you're healthy, have strong savings, and plan to self-insure, that's a legitimate choice. Just make it knowing you may not get a second chance at the same terms.
What If You Can't Afford Medigap?
You have more options than "full Medigap or nothing."
High-Deductible Plan G
High-Deductible Plan G offers the same covered benefits as standard Plan G once its annual deductible is met, but generally has lower monthly premiums.
With High-Deductible Plan G, Medicare continues paying its share of covered services.
You pay Medicare's deductibles, copayments, and coinsurance until you've met the plan's annual deductible. After that, the policy pays its covered share for the rest of the calendar year.
How much lower depends on your age, location, and insurance company.
Our High-Deductible Plan G guide walks through how to tell whether the math works for you, and our Plan G vs. Plan N vs. High-Deductible Plan G comparison shows how it stacks up.
Medicare Advantage
Many Advantage plans have low or $0 premiums.
They also have annual out-of-pocket limits for covered Part A and Part B services, although the limits and costs can differ for in-network and out-of-network care.
The trade-offs are networks, prior authorization, and copays that can add up. If you later want Medigap, you may have to pass medical underwriting unless you have a trial right or other guaranteed issue right.
I cover how I help clients weigh these trade-offs in Medicare Advantage vs. Medigap.
Help With Costs
If your income and resources are limited, check whether you qualify for a Medicare Savings Program or Medicaid before buying anything.
Questions to Ask Before You Decide
- Do I already have coverage that pays after Medicare, like retiree coverage, Medicaid, or TRICARE For Life?
- If I had a $10,000 or $30,000 medical bill this year, could I pay it without real hardship?
- Am I still inside my six-month Medigap Open Enrollment Period?
- Can I comfortably afford a Medigap premium for years, not just this year?
- Do I need to keep specific doctors, or travel often within the U.S.?
- Have I compared the total yearly cost, premiums plus likely out-of-pocket costs, for each option? (Our Medigap cost calculator can help.)
Bottom Line
You aren't required to buy supplemental insurance with Original Medicare, but going without it leaves you exposed to medical bills with no yearly limit.
Here's how I'd decide:
- If you have Medicaid, QMB, or TRICARE For Life, you likely don't need Medigap.
- If you have retiree coverage, compare it with Medigap before adding anything.
- If Original Medicare would be your only coverage, compare Medigap premiums against the financial risk of paying Medicare's deductibles and coinsurance yourself.
- If the premium is the obstacle, look at High-Deductible Plan G and assistance programs.
