That's the gap Medigap is built to fill. Medigap, also called Medicare Supplement insurance, is private coverage that helps pay certain out-of-pocket costs left behind by Original Medicare.
This guide walks through how Medigap actually works, what it covers (and doesn't), how it stacks up against Medicare Advantage, what it tends to cost, and when enrollment timing can make or break your options.
Key Takeaways
- Medigap and Medicare Supplement insurance are the same coverage under two names.
- You generally need Medicare Part A and Part B before you can buy a Medigap policy.
- Coverage helps with cost-sharing but doesn’t cover prescription drugs, routine dental, vision, or hearing aids.
- Premiums and enrollment rules vary by state, so verify details on Medicare.gov before you enroll.
What Is Medigap and How Does It Work?
Medigap policies are sold by private insurance companies, not the government. Their job is straightforward: pick up some of the costs Original Medicare leaves on the table after it processes a covered claim.
Here's the payment order:
- Medicare pays first, covering its share of an approved service.
- Your Medigap plan pays second, based on whatever benefits your specific plan letter includes.
- You're still responsible for your monthly premiums and anything neither Medicare nor Medigap covers.
Who Can Actually Buy a Medigap Policy
You generally need to be enrolled in both Part A and Part B first. Medigap policies cover only one person, so married couples need separate policies from a private insurer.
Under-65 access gets murkier. Federal law doesn't require insurers to sell Medigap to beneficiaries under 65.
That said, Medicare.gov's guide to Medigap eligibility notes that some states extend coverage to people who qualify through disability or End-Stage Renal Disease. Check your state's rules directly if this applies to you.
Standardized Plans, Different Prices
Here's what makes Medigap unusual: in most states, a Plan G from one insurer covers the exact same benefits as a Plan G from another. The letter defines the benefits. The insurer only affects the price, customer service, and discounts.
Ten standardized plans currently exist: A, B, C, D, F, G, K, L, M, and N (Massachusetts, Minnesota, and Wisconsin standardize differently). But Plans C and F come with a catch worth knowing about upfront.
If you became newly eligible for Medicare on or after January 1, 2020, you cannot buy Plan C or Plan F.
According to Medicare's official Medigap guide, these plans are closed to new enrollees because they cover the Part B deductible, something newer Medigap policies aren't allowed to do. Plan G is now the most comprehensive option available to new buyers.
What Does Medigap Cover and Not Cover?
Medigap benefits focus on cost-sharing gaps, not new categories of care. Depending on the plan you choose, coverage can include:
- Part A hospital coinsurance and up to 365 extra hospital days after Medicare benefits run out
- Part B coinsurance or copayments
- Hospice care coinsurance or copayments
- The first three pints of blood needed for a transfusion
- Skilled nursing facility coinsurance (select plans)
- The Part A deductible (select plans)
- Part B excess charges (select plans)
- Emergency medical care during foreign travel, up to plan limits
How the Popular Plans Differ
Three plans dominate the market, and each fits a different priority:
- Plan G covers nearly everything except the Part B deductible. It is the most complete option for new Medicare enrollees and the top-selling plan nationally.
- Plan N trades a lower premium for copays—up to $20 for some office visits and $50 for ER visits without admission. It also skips Part B excess charge coverage.
- High-deductible Plan G keeps premiums low in exchange for a higher deductible before benefits start. That trade-off suits people comfortable holding some risk.
What Medigap Won't Touch
Medigap plans typically exclude:
- Prescription drugs (any policy sold after 2005 excludes this entirely)
- Routine dental, vision, and eyeglasses
- Hearing aids
- Long-term custodial care
- Private-duty nursing
Picture a retiree with Plan G. The plan covers her hospital coinsurance and Part B coinsurance. She still pays out of pocket for monthly prescriptions unless she adds a standalone Part D plan, and she needs separate coverage for routine dental care.
What Is the Main Difference Between Medicare Advantage and Medigap?
This is where a lot of confusion happens, so let's be direct about it: Medicare Advantage replaces how you get Part A and B benefits. Medigap supplements Original Medicare. You don't layer them together.
| Factor | Medicare Advantage | Medigap |
|---|---|---|
| How it works | Private plan replaces Original Medicare | Supplements Original Medicare |
| Provider access | Usually network-based | Any provider accepting Medicare |
| Referrals/prior authorization | Often required | Not required |
| Prescription drugs | Frequently bundled in | Requires separate Part D plan |
| Extra benefits (dental, vision) | Sometimes included | Not included |
| Monthly premium | Often $0, but variable cost-sharing | Separate premium, more predictable costs |
You cannot use a Medigap policy to pay a Medicare Advantage plan's copayments, deductibles, or premium. If you want Medigap later, you must return to Original Medicare first and meet the enrollment or guaranteed-issue rules that apply at that time.
Who Tends to Prefer Medigap
Medigap appeals most to people who:
- Travel frequently or split time between two states and want provider access wherever they go
- Prefer seeing any doctor who accepts Medicare, without network restrictions
- Value predictable monthly costs over lower premiums with variable cost-sharing
- Are willing to pay a separate Part D premium in exchange for that flexibility
How Much Does Medigap Cost and When Can You Enroll?
Medigap costs stack on top of your existing Medicare expenses, not instead of them. You're typically paying for:
- Your Part B premium (and Part A premium, if applicable)
- Your Medigap monthly premium
- A separate Part D premium if you want drug coverage
- Any remaining cost-sharing your plan doesn't cover
There's no single national price tag. According to KFF's analysis of NAIC data, the average Medigap premium across all plan types was $217 per month in 2023, ranging from $191 in Alaska to $267 in New York. Plan G averaged $164 monthly nationally, while Plan F averaged $274.
Your actual quote depends on your plan letter, insurer, location, age, tobacco use, and available household discounts.
Three Ways Insurers Price Policies
- Community-rated: Everyone pays the same premium regardless of age. Rates rise from inflation, not birthdays.
- Issue-age-rated: Your premium locks in based on your age at purchase. Buy younger, pay less, permanently.
- Attained-age-rated: Your premium climbs as you age. Often cheapest at first, but frequently the priciest over time.
Ask any insurer which method they use before comparing quotes. Two plans with identical benefits can diverge wildly in cost ten years down the road depending on this one detail.
When You Have the Strongest Buying Power
Your six-month Medigap Open Enrollment Period begins the first month you're 65 or older and enrolled in Part B. During this window, insurers can't deny you coverage or charge more because of your health history.
That window is different from Medicare's Annual Enrollment Period (October 15 to December 7). AEP lets you switch Medicare Advantage or Part D plans, but it does not give you guaranteed Medigap access without medical underwriting.
Miss the six-month Medigap window and you may still qualify through limited guaranteed-issue rights, often triggered by situations such as:
- Losing employer group coverage
- Leaving a Medicare Advantage plan during your 12-month trial right period
- Your insurer going bankrupt or leaving the market
Guaranteed-issue rights, plan availability, and premiums vary by state and can change year to year, so confirm your situation on Medicare.gov and with your state insurance department before applying.
How to Decide Whether Medigap Fits Your Needs
Before choosing a Medigap plan, walk through your own situation honestly:
- How often do you actually use healthcare, and how unpredictable are those costs?
- Do you want freedom to see any Medicare-participating provider, or are you fine with a network?
- Do you travel often or spend part of the year in another state?
- Are you managing ongoing prescriptions that need separate Part D coverage?
- Can you comfortably absorb a higher monthly premium in exchange for fewer surprise bills?
- Do you need dental, vision, or hearing coverage that Medigap won't provide?
Once you know what you need, compare the same lettered plan across several insurers. Since benefits are standardized, the differences come down to pricing method, rate history, discounts, and how the company handles renewals and claims.
If you're in Florida, Georgia, North Carolina, Nevada, or South Carolina, Wareheim Medicare Advisors offers personalized, no-cost brokerage guidance and annual plan reviews. Jim Wareheim has worked with Medicare beneficiaries since 1998.
He compares Medigap, Medicare Advantage, and Part D options against your health needs, budget, and preferred providers—whether you're turning 65, leaving employer coverage, or rechecking a plan that no longer fits.
That said, educational guidance never replaces official plan documents. Cross-check anything you decide against Medicare.gov, a State Health Insurance Assistance Program counselor, your state insurance department, or a licensed Medicare professional.
Frequently Asked Questions
How much does Medigap cost?
Premiums vary by plan letter, insurer, location, age, and pricing method. National averages run about $164 to $217 per month, and you still pay your Part B premium plus any Part D premium.
What is the main difference between Medicare Advantage and Medigap?
Medicare Advantage is a private plan that replaces Original Medicare for Part A and B benefits. Medigap supplements Original Medicare instead, and the two cannot be combined to cover each other's costs.
What's the difference between Medicare and Medicare Supplemental?
Medicare is the federal health insurance program itself. Medicare Supplement, or Medigap, is private insurance that helps pay costs Original Medicare does not cover.
Why would I want Medigap insurance?
Medigap offers more predictable out-of-pocket costs and broad access to any Medicare-participating provider nationwide. You'll still pay a separate premium and need standalone Part D coverage for prescriptions.
Can I have Medigap and Medicare Advantage at the same time?
No. Medigap generally cannot pay Medicare Advantage costs. Insurers also cannot sell you a Medigap policy while you are enrolled in Advantage, except when you are switching back to Original Medicare.
When is the best time to enroll in Medigap?
Your strongest window is the six-month Medigap Open Enrollment Period, which starts when you turn 65 and enroll in Part B. Guaranteed-issue rights may open other windows based on your situation.
