16.3 Medicare Supplement (Medigap) Standardized Plans and Enrollment
Key Takeaways
- Medigap fills Original Medicare's deductibles and coinsurance and works only with Original Medicare, not Medicare Advantage.
- Medigap plans are federally standardized (A-N); identical letters offer identical benefits, so insurers compete on price and service.
- Plan F is closed to those newly eligible on or after January 1, 2020; Plan G is the comprehensive alternative.
- The 6-month Medigap Open Enrollment Period (age 65 + Part B) gives guaranteed-issue rights with no health-based denial or surcharge.
- Medigap covers only the policyholder, carries a 30-day free look, and may impose up to a 6-month pre-existing-condition wait reduced by prior creditable coverage.
What Medigap Does
Medicare Supplement insurance, commonly called Medigap, is a private policy that fills the gaps in Original Medicare — the deductibles, coinsurance, and copayments that Parts A and B leave to the beneficiary. Because Original Medicare has no out-of-pocket maximum, Medigap is the tool consumers use to make their costs predictable.
Medigap works only with Original Medicare. It does not work with Medicare Advantage, does not include prescription drug coverage (those sold after 2006 cannot), and covers only the policyholder — spouses need their own policies.
Standardization: Plans A through N
Medigap policies are federally standardized into lettered plans (A, B, C, D, F, G, K, L, M, N) in most states. Standardization means Plan G from one insurer must offer the identical benefits as Plan G from any other insurer — only the price and the company's service differ. This is a core exam point: agents compete on price and service, not benefit design.
- Plan A is the basic benefit package every insurer that sells Medigap must offer.
- Plans F and G are the most comprehensive; Plan F (which covered the Part B deductible) is closed to people newly eligible on or after January 1, 2020 — they can buy Plan G instead.
- Plans K and L are cost-sharing plans with their own annual out-of-pocket limits.
Benefit Comparison (selected high-value plans)
| Benefit | Plan G | Plan N | Plan K |
|---|---|---|---|
| Part A coinsurance + 365 extra hospital days | 100% | 100% | 100% |
| Part B coinsurance | 100% | 100% (small copays apply) | 50% |
| First 3 pints of blood | 100% | 100% | 50% |
| Part A hospice coinsurance | 100% | 100% | 50% |
| SNF coinsurance | 100% | 100% | 50% |
| Part A deductible | 100% | 100% | 50% |
| Part B deductible | Not covered | Not covered | Not covered |
| Part B excess charges | 100% | Not covered | Not covered |
Note: the 365 additional hospital days benefit pays for inpatient days after Original Medicare's lifetime reserve days are exhausted — a benefit every plan from A up must include.
The Medigap Open Enrollment Period (Guaranteed Issue)
The most heavily tested Medigap rule is the Medigap Open Enrollment Period: a one-time, 6-month window that begins on the first day of the month in which the applicant is both age 65 or older and enrolled in Part B.
During this window the applicant has guaranteed-issue rights: the insurer cannot deny coverage, charge a higher premium, or impose a waiting period based on health. Outside this window (and outside other guaranteed-issue situations such as losing employer coverage or an MA plan leaving the area), the insurer may use medical underwriting and decline or surcharge the applicant.
Pre-existing conditions: during open enrollment an insurer may impose up to a 6-month pre-existing-condition waiting period, reduced by any months of prior creditable coverage.
Worked Scenario: Underwriting vs. Guaranteed Issue
A client turns 65 on March 15 and enrolls in Part B effective March 1.
- His Medigap Open Enrollment Period runs March 1 through August 31 (6 months).
- If he applies in June, the insurer must issue him any Medigap plan it sells at the standard rate regardless of his diabetes — guaranteed issue.
- If he waits and applies the following January, the insurer may underwrite, charge more, or decline him.
Trap: the open-enrollment window is tied to age 65 + Part B enrollment, not to the calendar or to turning 65 alone. Disabled beneficiaries under 65 may not get the same federal guarantee, though many states extend it.
Replacement, Free Look, and Suitability
When replacing one Medigap policy with another, agents must follow replacement rules: provide a Notice Regarding Replacement, avoid duplicate coverage, and never sell a policy that duplicates existing benefits.
- Medigap policies carry a 30-day free-look period — the buyer may return the policy for a full premium refund.
- The Outline of Coverage must be delivered at the time of application.
- It is an illegal sales practice to sell a Medigap policy to someone on Medicaid or to knowingly sell a duplicate or to a Medicare Advantage enrollee.
These consumer-protection rules are tested as the agent's duties of suitability and disclosure.
A man enrolls in Part B effective the month he turns 65. He applies for a Medigap policy four months later but has a serious heart condition. What is true during his Medigap Open Enrollment Period?
Because Medigap plans are federally standardized, how do two insurers' Plan G policies differ?
What Medigap Does and Does Not Cover
A Medicare Supplement (Medigap) policy pays the gaps in Original Medicare deductibles, coinsurance, and copays. It is standardized into lettered plans (A, B, C, D, F, G, K, L, M, N) that are identical across insurers, so only price and service differ.
Medigap does not include drug coverage (that is Part D), and you cannot use Medigap with a Medicare Advantage plan they are alternatives, not companions.
| Fact | Rule |
|---|---|
| Works with | Original Medicare (Parts A & B) |
| Drug coverage | No use Part D |
| Use with Medicare Advantage | Not allowed |
| Plans available to new enrollees | Plans that do not pay the Part B deductible (e.g., G, N) |
A consumer can use a Medicare Supplement (Medigap) policy together with which of the following?
The Medigap Open Enrollment Period
The Medigap Open Enrollment Period is a one-time, 6-month window that starts when the person is age 65 and enrolled in Part B. During it, the applicant has a guaranteed-issue right insurers must sell any offered plan, cannot apply medical underwriting, and cannot charge more for health conditions.
Apply after this window and the insurer may medically underwrite and decline or surcharge an applicant (outside of separate guaranteed-issue events). This is why timing the enrollment is heavily tested.
Exam Tip: The 6-month Medigap OEP (age 65 + Part B) is the consumer's golden window for guaranteed issue with no health questions. Missing it can mean underwriting later.