Medicare Supplements Explained
Medicare Supplement Insurance, also called Medigap, works alongside Original Medicare to help pay certain deductibles, copayments and coinsurance. It offers broad provider access and more predictable medical expenses, but it also requires a separate monthly premium.
What Is a Medicare Supplement?
A Medicare Supplement is private insurance designed to help cover certain costs left behind by Original Medicare Parts A and B. These policies are commonly called Medigap because they help fill some of Medicare’s financial “gaps.”
When you receive a Medicare-covered service, Original Medicare generally processes the claim first. Your Medicare Supplement then pays its share according to the benefits included in your plan letter.
What Medicare Supplements Can Cover
The exact benefits depend on the plan letter you select. Depending on the plan, Medigap may help cover:
Common Medigap Benefits
- Medicare Part A hospital coinsurance
- Additional hospital days after Medicare benefits are used
- Medicare Part B coinsurance or copayments
- The first three pints of blood
- Part A hospice cost sharing
- Skilled nursing facility coinsurance on certain plans
- The Medicare Part A deductible on certain plans
- Limited foreign-travel emergency coverage on certain plans
What Medigap Generally Does Not Cover
- Routine outpatient prescription drugs
- Routine dental care
- Routine vision examinations or eyeglasses
- Hearing aids
- Long-term custodial care
- Private-duty nursing
- Services Original Medicare does not approve, unless specifically covered
A Medigap policy generally does not turn a service that Original Medicare excludes into a covered service. Read more about dental, vision and hearing coverage under Medicare .
Does Medigap Have a Doctor Network?
Standard Medicare Supplement policies generally do not use traditional provider networks. You can usually receive Medicare-covered care from any doctor or hospital nationwide that accepts Medicare.
Nationwide Access
Your coverage is not limited to a regional HMO or PPO network. This can be helpful for people who travel, split time between states or receive care in several communities.
No Plan Referrals
Original Medicare generally does not require a referral before you see a specialist. The provider must still accept Medicare and be willing to accept you as a patient.
Travel Flexibility
Medigap can travel with you throughout the United States. Certain plan letters also provide limited emergency coverage outside the country, subject to plan limits.
See the specific domestic and foreign-travel rules in the guide to Medicare coverage while traveling .
Plan Letters Versus Insurance Companies
In most states, Medicare Supplements are standardized into plan letters. Plans with the same letter provide the same standardized medical benefits regardless of which insurance company sells them.
For example, one insurance company’s standard Plan G covers the same standardized Medicare gaps as another company’s standard Plan G. The companies can still differ in several important ways:
- Monthly premium
- Rate-increase history
- Pricing method
- Household or payment-method discounts
- Customer service and administration
- Financial stability
- Eligibility and medical-underwriting requirements
Plan G, Plan N and Plan F
| Plan | General Structure | Important Considerations |
|---|---|---|
| Plan G | Covers most standardized Medicare cost-sharing gaps after you pay the annual Medicare Part B deductible. | Usually has fewer routine out-of-pocket medical expenses than Plan N, but the premium may be higher. |
| Plan N | Covers many of the same major gaps as Plan G but may require certain office and emergency-room copayments. | Does not cover the Part B deductible or Part B excess charges. Premiums may be lower than Plan G, depending on the applicant and carrier. |
| High-Deductible Plan G | Requires you to pay Medicare-covered costs up to an annual deductible before the supplement begins paying. | May offer a lower monthly premium in exchange for greater initial out-of-pocket exposure. |
| Plan F | Covers the standardized gaps that include the Medicare Part B deductible. | Available only to people who were eligible for Medicare before January 1, 2020. People first eligible after that date cannot purchase it. |
Other standardized plan letters are also available. No one plan letter is automatically suitable for everyone. The decision should consider premium, expected healthcare use, rate history and the amount of cost sharing you are comfortable accepting.
Your Medigap Open Enrollment Period
Your One-Time Federal Enrollment Period
Your federal Medigap Open Enrollment Period begins the first month you are both age 65 or older and enrolled in Medicare Part B. It lasts for six months.
This is separate from Medicare’s October 15–December 7 Annual Enrollment Period.
Protection During This Period
During your Medigap Open Enrollment Period, an insurance company cannot deny you one of the Medigap policies it sells or charge you more because of your current or previous health conditions.
Medical Underwriting and Guaranteed-Issue Rights
Outside of a protected enrollment period, an insurance company may be allowed to review your health history before approving a new Medicare Supplement application. Depending on the company and situation, it may:
- Ask medical questions
- Review prescriptions or recent medical treatment
- Decline the application
- Apply a different available rate class where permitted
Certain events can provide a guaranteed-issue right. Examples may include losing qualifying coverage through no fault of your own, certain Medicare Advantage trial rights or a Medicare Supplement company leaving the market.
The exact policy choices, deadlines and documents required depend on the guaranteed-issue situation. Keep termination notices, plan letters and proof of previous coverage.
Missouri and Illinois Medigap Switching Rules
Missouri Anniversary Rule
Missouri provides qualifying current Medigap policyholders an annual opportunity around their policy anniversary to move to the same plan letter with another insurer without medical underwriting.
The protected period generally runs from 30 days before through 30 days after the policy’s anniversary date. It is based on the policy anniversary, not the beneficiary’s birthday.
For example, a qualifying Plan G policyholder may compare another company’s Plan G. Changing from Plan G to a different plan letter is not protected by this same-letter anniversary rule.
Illinois Birthday Protection
Illinois provides an annual 45-day enrollment period beginning on the birthday of certain Medigap policyholders who are at least 65 but no older than 75.
A qualifying person may purchase another Medigap policy from the same insurance company with benefits equal to or less than the existing coverage without medical underwriting.
Because the Illinois rule includes age, carrier, timing and benefit-level requirements, eligibility should be checked before changing coverage.
How Medicare Supplement Premiums Are Priced
Insurance companies may use different rating methods when setting Medigap premiums. The pricing method is important, but it does not guarantee how much a policy will cost in future years.
Community-Rated
The same base premium is generally charged to everyone in the applicable rating group, regardless of age. Premiums can still increase because of inflation, claims experience and other approved factors.
Issue-Age-Rated
The premium is based partly on your age when the policy is issued. It does not increase merely because you get older, but it can still rise for inflation, claims experience and other approved reasons.
Attained-Age-Rated
The premium is based partly on your current age and may increase as you grow older. It can also increase because of inflation, claims experience and other approved factors.
Your actual premium may also be affected by location, tobacco status, household discounts, payment method, sex where permitted, eligibility and the insurance company’s approved rates.
Medicare Supplement Versus Medicare Advantage
| Consideration | Original Medicare With Medigap | Medicare Advantage |
|---|---|---|
| How coverage works | Original Medicare pays first, and the supplement helps cover specified remaining costs. | A private plan administers your Medicare Part A and Part B benefits. |
| Providers | Generally any nationwide provider who accepts Medicare. | Provider networks and service areas commonly apply. |
| Monthly premiums | Part B premium, Medigap premium and usually a separate Part D premium. | Part B premium plus any applicable Medicare Advantage plan premium. |
| Medical expenses | Often more predictable, depending on the selected plan letter. | Plan-specific copayments and coinsurance generally apply as services are used. |
| Prescription coverage | A separate Part D plan is generally needed. | Many plans include Part D coverage. |
| Additional benefits | Routine dental, vision and hearing benefits are generally not included. | Plans may include additional dental, vision, hearing or other benefits. |
| Prior authorization | Original Medicare generally does not use plan-network prior authorization in the same way as Medicare Advantage. | Prior authorization may apply to certain services under the plan’s rules. |
Neither approach is automatically better for everyone. The appropriate choice depends on provider access, premiums, expected healthcare use, prescriptions, travel, budget and tolerance for future out-of-pocket expenses.
Learn more about Medicare Advantage →
Explore local comparisons: See how provider access, costs and travel considerations affect the choice between Medicare Advantage and Medicare Supplement coverage in Springfield or Medicare Advantage and Medigap in rural Missouri.
What Should You Review Before Enrolling?
- Your Medicare Part A and Part B effective dates
- Your Medigap Open Enrollment or guaranteed-issue status
- The standardized plan letter and benefits
- The current monthly premium
- The company’s recent rate-increase history
- Whether the policy is community, issue-age or attained-age rated
- Available household and payment-method discounts
- Whether medical underwriting applies
- The insurer’s financial stability and customer service
- The cost and coverage of a separate Part D plan
- Your dental, vision and hearing coverage needs
A useful comparison looks beyond the first-year premium. It should also consider how the policy fits your healthcare preferences and what options may be available if the premium changes later.
Medicare Supplement Questions
Is Medigap the same as Medicare Advantage?
No. Medicare Advantage is another way to receive your Medicare benefits through a private plan. Medigap works alongside Original Medicare and helps pay certain costs Original Medicare leaves behind.
Do Medicare Supplements cover prescriptions?
Medicare Supplements sold today generally do not include routine outpatient prescription coverage. People with Original Medicare and Medigap commonly enroll in a separate Part D plan.
Do Medicare Supplements include dental and vision?
Standardized Medigap medical benefits generally do not include routine dental, vision or hearing coverage. Separate coverage may be available.
Can I see any doctor with a Medicare Supplement?
You can generally see any doctor or hospital nationwide that accepts Medicare. The provider must still be willing to accept you as a patient. Medicare SELECT policies can have additional provider requirements.
Can I buy Plan F?
Plan F is available only to people who were eligible for Medicare before January 1, 2020. People first eligible for Medicare on or after that date cannot purchase Plan F or Plan C.
Can I switch Medicare Supplements at any time?
You may apply to switch at any time, but medical underwriting may apply outside a protected enrollment period. Guaranteed-issue rights and additional state protections may provide an opportunity to change coverage without underwriting in certain circumstances.
Does the fall Annual Enrollment Period apply to Medigap?
Not in the same way. The October 15–December 7 Annual Enrollment Period primarily concerns Medicare Advantage and Part D. It does not create a universal annual guaranteed-issue period for Medicare Supplements.
Can my Medicare Supplement be canceled if I become sick?
Standard Medigap policies issued since 1992 are generally guaranteed renewable. The insurer generally cannot cancel the policy because your health changes, provided premiums are paid and the application did not contain a material misrepresentation.
Why do two companies charge different prices for Plan G?
The standardized Plan G medical benefits are the same, but insurance companies set their own approved premiums and may use different pricing methods, discounts, eligibility rules and rate structures.
Compare Medicare Supplement Options
Benjamin Thompson can help you compare Medicare Supplement plan letters, insurance companies, premiums, discounts and enrollment rights. I will also help you understand how Medigap compares with Medicare Advantage and how separate Part D coverage fits into the decision.
Thompson Medicare Brokerage provides no-cost, no-obligation consultations throughout Missouri and Illinois, with telephone, virtual and appointment-based local assistance available.
This page provides general educational information and is not a substitute for individualized guidance from Medicare, a state insurance department or another appropriate agency. Policy availability, premiums, underwriting, discounts, enrollment rights and state protections vary by applicant, insurance company, location and effective date.