13.2 Medicare Supplement (Medigap) Policies
Key Takeaways
- Medigap fills Original Medicare gaps; the applicant must have both Part A and Part B.
- Medigap covers one person and does not combine with Medicare Advantage.
- Benefits are standardized into letter plans, so same-letter plans are identical across carriers.
- Open Enrollment is a one-time six-month window with no underwriting allowed.
- Plans C and F are closed to those first eligible on or after January 1, 2020.
Medicare Supplement insurance, universally called Medigap, is private coverage that fills the deductibles, copayments, and coinsurance gaps left by Original Medicare. Because Original Medicare has no out-of-pocket maximum, Medigap is how beneficiaries cap their exposure while keeping free provider choice.
Core Rules
- The applicant must already be enrolled in BOTH Part A and Part B.
- Medigap pays AFTER Medicare pays its share; it is true supplemental coverage.
- A Medigap policy covers only one person, so a married couple needs two separate policies.
- Medigap does NOT work with a Medicare Advantage plan; it pairs only with Original Medicare.
Standardized Plans
Medigap benefits are standardized by federal law into letter plans (A, B, C, D, F, G, K, L, M, N). Plan G with the same letter is identical across every carrier, so consumers compare on price and service, not benefit lists.
| Plan | Notable Feature |
|---|---|
| A | Basic core benefits only |
| F | Covers Part B deductible (closed to those newly eligible on/after 1/1/2020) |
| G | Like F but no Part B deductible; top seller for new enrollees |
| K / L | Cost-sharing plans with annual out-of-pocket limits |
| N | Lower premium with small copays at office and ER visits |
Trap: Plans C and F cover the Part B deductible and are closed to anyone first eligible for Medicare on or after January 1, 2020. Those newly eligible typically buy Plan G instead.
Open Enrollment and Guaranteed Issue
The Medigap Open Enrollment Period is a one-time, six-month window that begins the first month a person is age 65 or older AND enrolled in Part B. During this window the carrier must issue any plan it sells regardless of health (no underwriting) and cannot charge more for health conditions.
Guaranteed-issue rights also arise in limited situations, such as losing employer coverage or an MA plan leaving the service area. Outside these windows, carriers may medically underwrite and decline applicants.
Worked Timeline
A woman turns 65 on March 10 and enrolls in Part B effective March 1.
- Her Medigap Open Enrollment runs March 1 through August 31 (6 months).
- If she applies September 1 with a heart condition and no guaranteed-issue right, the carrier may underwrite, surcharge, or decline her.
Core Benefits and Pricing Methods
Every lettered plan (except the bare minimum) must include the same set of core benefits: Part A coinsurance plus 365 extra hospital days, Part B coinsurance/copayment, the first three pints of blood, and Part A hospice cost-sharing. Higher letters layer on extras such as the skilled nursing coinsurance, the Part A deductible, foreign-travel emergency care, and (in F/G) Part B excess charges.
Carriers may price the same plan three ways, and exam items test the difference:
| Rating Method | How Premiums Behave |
|---|---|
| Issue-age | Based on age at purchase; does not rise with age |
| Attained-age | Rises as the insured grows older |
| Community-rated (no-age) | Same premium for all insureds regardless of age |
Renewability and Free Look
Medigap policies are guaranteed renewable: the insurer cannot cancel for health changes and must renew as long as premiums are paid and no material misrepresentation occurred. Federal rules require a 30-day free-look period, during which the buyer may return the policy for a full refund. Replacement of one Medigap policy with another triggers a replacement notice and a new free-look, and the carrier must waive any new pre-existing-condition waiting period to the extent already satisfied.
Suitability and Marketing Traps
It is an unlawful practice to sell a beneficiary a second Medigap policy that duplicates coverage they already own, or to sell Medigap to someone enrolled in Medicaid or a Medicare Advantage plan, except in narrow circumstances. Producers must complete a suitability review and may not use high-pressure tactics.
Trap: Medigap pre-existing-condition exclusions may apply for up to 6 months if the applicant did NOT enroll during Open Enrollment or a guaranteed-issue window. Prior creditable coverage shortens or eliminates this look-back.
What Medigap Excludes
Medigap does not cover long-term custodial care, routine dental, vision, hearing aids, private-duty nursing, or (for policies sold after 2006) prescription drugs. Drug coverage must come from a separate Part D plan.
A man becomes eligible for Medicare and enrolls in Part B effective June 1 at age 65. When does his six-month Medigap Open Enrollment Period end?
Which Medigap feature is closed to beneficiaries first eligible for Medicare on or after January 1, 2020?
The Standardized-Plan Grid, the OEP, and a Coverage-Gap Worked Example
Medigap is standardized by federal law into lettered plans (A through N), so a plan of a given letter offers identical core benefits no matter which insurer sells it — only price and service differ. This standardization is the most-tested Medigap fact.
| Feature | Rule |
|---|---|
| Standardization | Lettered plans A–N; benefits identical by letter |
| Open Enrollment Period | 6 months starting at 65 AND enrolled in Part B |
| Guaranteed issue in OEP | No medical underwriting during the window |
| Relationship to Medicare | Pays Medicare's gaps; not stand-alone coverage |
| Plans C and F | Cover the Part B deductible; closed to newly eligible after 2020 |
The 6-month Medigap Open Enrollment Period is the candidate's key date: it begins the month a person is 65 or older and enrolled in Part B, and during it the insurer must issue any offered plan with no underwriting regardless of health. Apply outside that window and the insurer may medically underwrite or decline (except in specific guaranteed-issue situations such as losing employer coverage). Note that free-look rules give 30 days to return a Medigap policy, and replacement of one Medigap with another requires the new plan to count toward the same standardized benefits.
Worked coverage-gap example showing what Medigap fills: a beneficiary incurs a $3,000 approved Part B charge. Original Medicare pays 80% = $2,400, leaving a 20% = $600 coinsurance with no cap. A Medigap plan covering Part B coinsurance pays that $600, so the beneficiary's out-of-pocket for the service is $0. Medigap never duplicates Medicare and never pays for custodial long-term care — a recurring trap. A beneficiary cannot hold both a Medigap policy and a Medicare Advantage (Part C) plan at the same time, because Advantage replaces Original Medicare rather than supplementing it.