16.3 Medicare Supplement (Medigap) Standardized Plans and Enrollment
Key Takeaways
- Medigap fills Original Medicare gaps, works only with Original Medicare, and cannot be paired with a Medicare Advantage plan.
- Medigap plans are federally standardized by letter, so the same plan letter offers identical core benefits across insurers.
- Plans C and F are closed to beneficiaries newly eligible on or after January 1, 2020; Plan G is the comprehensive default.
- The one-time 6-month Medigap Open Enrollment Period starts when the person is both 65+ and enrolled in Part B, with guaranteed issue.
- Required protections include the Outline of Coverage, a 30-day free look, and the prohibition on duplicate coverage.
What Medigap Does
Medicare Supplement (Medigap) policies are sold by private insurers to fill the gaps in Original Medicare, chiefly the Part A deductible/coinsurance and the open-ended Part B 20% coinsurance. Medigap works only with Original Medicare; a person cannot use a Medigap policy alongside a Medicare Advantage plan. Selling Medigap to someone enrolled in an MA plan, except when they are disenrolling, is an illegal duplicate sale.
Medigap pays after Medicare. It does not include prescription drug coverage; beneficiaries needing drugs buy a separate Part D plan.
Standardization
Medigap plans are standardized by federal law into lettered plans (A, B, C, D, F, G, K, L, M, N; Massachusetts, Minnesota, and Wisconsin have their own systems). A Plan G from one insurer offers the same core benefits as a Plan G from another; only price and service differ. This is a frequent exam point: the benefits are identical across carriers, so consumers should comparison-shop on premium.
Standardized Plan Comparison (selected)
| Plan | Part A deductible | Part B deductible | Part B excess charges | Notes |
|---|---|---|---|---|
| A | No | No | No | Basic core benefits only |
| F | Yes | Yes | Yes | Most comprehensive; closed to those newly eligible after 1/1/2020 |
| G | Yes | No | Yes | Like F but no Part B deductible coverage |
| N | Yes | No | No | Copays at office/ER visits |
| K / L | Partial (50% / 75%) | No | No | Cost-sharing plans with out-of-pocket limits |
The 2020 Rule (Plans C and F)
Plans that pay the Part B deductible (C and F) are closed to beneficiaries who became eligible for Medicare on or after January 1, 2020. Those eligible before that date can still buy or keep C and F. Newly eligible beneficiaries gravitate to Plan G, now the most comprehensive widely available option.
Worked Gap-Fill Example
Recall the section 16.1 example: a beneficiary owed $800 in Part B coinsurance on $4,000 of approved charges. A Plan G covers that $800 (after the beneficiary pays the Part B deductible). On the Part A side, Plan G also covers the ~$1,676 hospital deductible, turning a multi-thousand-dollar exposure into predictable premiums.
The Medigap Open Enrollment Period (Critical)
The Medigap Open Enrollment Period (OEP) is a one-time, 6-month window that begins on the first day of the month the beneficiary is both 65 or older AND enrolled in Part B. During this window, the insurer must issue any Medigap policy it sells with guaranteed issue: no medical underwriting, no denial, and no premium surcharge for health conditions.
Miss this window and the insurer may use medical underwriting, charge more, or decline the applicant outside of certain guaranteed-issue situations (such as losing other coverage). This 6-month, age-65-plus, Part-B-enrolled trigger is one of the most tested facts in the entire health portion.
Required Consumer Protections
- Outline of Coverage must be delivered at or before application.
- 30-day free-look period: the buyer may return the policy for a full refund.
- Guide to Health Insurance for People with Medicare must be provided.
- No duplication: it is illegal to sell a Medigap policy that duplicates coverage the buyer already has.
- Replacement rules: when replacing an existing Medigap policy, the producer must complete a replacement notice and not subject the client to a new pre-existing condition wait if already satisfied.
Medigap insurers may impose up to a 6-month pre-existing condition waiting period, reduced by prior creditable coverage.
A beneficiary turned 65 and enrolled in Part B on March 1. When does her one-time Medigap Open Enrollment Period end, and what protection does it provide?
Which statement about Medicare Supplement (Medigap) policies is correct?
Key Takeaways
- Medigap fills gaps in Original Medicare only and cannot pair with Advantage.
- Plans are standardized by letter; same letter = same core benefits, differing only by price.
- Plans C and F are closed to those newly eligible on/after 1/1/2020; Plan G is the comprehensive default.
- The 6-month Medigap OEP (age 65+ and Part B enrolled) gives guaranteed issue with no underwriting.
- Required protections: Outline of Coverage, 30-day free look, and the no-duplication rule.
Guaranteed-Issue Rights Beyond Open Enrollment
The 6-month Medigap Open Enrollment Period (starting when the beneficiary is 65+ and enrolled in Part B) gives a guaranteed-issue right with no medical underwriting. Outside that window, several guaranteed-issue (trial-right) situations still bar underwriting: losing employer retiree coverage, a Medicare Advantage plan leaving the service area, or the beneficiary trying Advantage at 65 and switching back to Original Medicare within 12 months. Outside these protections, insurers may medically underwrite a Medigap applicant.
What Medigap Does Not Cover
Medigap supplements Original Medicare only — it pays the deductibles, copays, and coinsurance gaps Parts A and B leave behind. It does not work with Medicare Advantage, does not include prescription drugs (that is Part D), and does not cover long-term custodial care, dental, vision, or hearing. Each lettered plan (A, B, D, G, K, L, M, N) is standardized, so the same letter offers identical benefits across all insurers; only price and service differ.
A beneficiary enrolls in Medicare Part B at 65 and applies for a Medigap policy three months later. During this period the insurer:
The 30-Day Free Look and Replacement
Medigap policies carry a 30-day free-look period during which a new policy can be returned for a full refund — useful when replacing an existing Medigap plan, because the buyer should not cancel the old policy until the new one is confirmed. To prevent duplication, federal law makes it illegal to sell a beneficiary a second Medigap policy or to sell Medigap to someone in a Medicare Advantage plan. Producers must complete a replacement notice and use the standardized outline of coverage so the buyer can compare lettered plans side by side.