This article provides general, evergreen education. Medicare rules, plan contracts, costs, and agency guidance can change. Confirm current information through the official sources listed below and the documents that apply to your own coverage.
Medicare Supplement Insurance, commonly called Medigap, is private insurance designed to help pay certain out-of-pocket costs left by Original Medicare. It is not the same as Medicare Advantage and generally does not replace Part A and Part B.
Relationship to Original Medicare
A person generally needs Part A and Part B to buy a Medigap policy. Original Medicare processes the covered claim first, and the Medigap policy may pay according to its standardized benefits.
Medigap is secondary coverage, not a separate way to receive Part A and Part B services.
Verify: Confirm that the policy is active and that Medicare has the correct crossover information.
Cost-sharing assistance
Depending on the standardized plan letter, Medigap can help with specified deductibles, copayments, coinsurance, or other gaps in Original Medicare.
No Medigap plan covers every possible health or support cost, and benefits differ by plan letter.
Verify: Use the official comparison chart and policy outline for the exact letter.
Standardization
In most states, policies with the same letter provide the same standardized core benefits regardless of insurer, although premiums, customer service, underwriting, and available discounts can differ. Massachusetts, Minnesota, and Wisconsin use different standardization systems.
Standardization makes benefit comparison easier, but it does not make every carrier relationship or price identical.
Verify: Verify state rules and compare insurers offering the desired standardized option.
Monthly premium
The enrollee pays a separate Medigap premium in addition to the Part B premium and any Part D premium. Insurers can use different pricing methods and may change premiums over time.
A lower introductory premium may not predict future increases or total household cost.
Verify: Ask how the policy is priced, how rates have changed, and what discounts or fees apply.
Provider access
Because Medigap works with Original Medicare, the central provider question is usually whether the provider accepts Medicare, not whether the provider is in a Medigap network. Certain Medicare SELECT policies may use networks.
A provider does not have to contract separately with every standard Medigap insurer for normal claim crossover.
Verify: Confirm Medicare participation and ask the insurer about any policy-specific restrictions.
Prescription drugs and other limits
Medigap policies sold today generally do not include outpatient prescription drug coverage. They also generally do not cover long-term custodial care, routine dental or vision care, hearing aids, or private-duty nursing.
The word “supplement” should not be interpreted as coverage for every service Medicare excludes.
Verify: Plan separately for Part D and for services outside both Original Medicare and the policy.
Common misunderstandings
- “Medigap and Medicare Advantage can be layered together.” Medigap is designed to work with Original Medicare, not to pay Medicare Advantage cost sharing.
- “The same letter means the same premium.” Standardized benefits can be the same while prices differ.
- “Medigap includes drug coverage.” Modern policies generally do not.
Questions to consider
- Which standardized benefits are important to me?
- What pricing method does the insurer use?
- What premium changes and discounts should I understand?
- Do I have separate Part D coverage?
- Does my state use special Medigap rules?