Medigap Policy Rules
Medigap — also called Medicare Supplement insurance — fills the coverage gaps that Original Medicare leaves open: deductibles, coinsurance, and copays that can add up to thousands of dollars in an unexpected illness or hospital stay. Federal law standardizes Medigap into eight plan types (A, B, D, G, G+, K, L, N), sold by private insurers at regulated benefit structures but variable premiums. Plan G has become the most popular choice for new enrollees since Plan F closed to newcomers in 2020 — typically running $150–$250/month, it covers your Part A hospital deductible, Part B coinsurance, Part B excess charges, and 80% of foreign travel emergency costs, leaving you responsible only for the annual Part B deductible (~$257 in 2026). The most important timing rule in Medigap: your open enrollment window is just 6 months, starting when you first enroll in Part B at age 65. During those 6 months, insurers must sell you any plan at standard rates regardless of health. Miss that window, and insurers in most states can underwrite you — denying coverage or charging more based on pre-existing conditions. Choosing the wrong plan or enrolling late can cost thousands of dollars annually for the rest of your life.
Current Law (2026)
Medigap (Medicare Supplement) plans fill gaps in Original Medicare coverage — deductibles, coinsurance, and copays. Sold by private insurers in 8 standardized plan types (A, B, D, G, G+, K, L, N).
| Plan | Part A Deductible | Part B Coinsurance | Part B Excess | Foreign Travel | Monthly Premium (est.) |
|---|---|---|---|---|---|
| G | 100% | 100% | 100% | 80% | $150-$250 |
| N | 100% | 100% (with copays) | No | 80% | $100-$180 |
Plan F (most comprehensive) is closed to new enrollees after 2020.
Legal Authority
- 42 U.S.C. § 1395ss — Certification of Medicare supplemental health insurance policies (Medigap standardization, guaranteed issue rights, open enrollment period, loss ratio requirements, state regulatory authority)
How It Works
The most consequential rule in Medigap — codified under 42 U.S.C. § 1395ss — is the guaranteed issue period: a 6-month window that starts when you are both age 65+ and enrolled in Medicare Part B. During those 6 months, insurers must sell you any Medigap plan at standard rates regardless of health history or pre-existing conditions. Once this window closes, most states allow medical underwriting — insurers can deny coverage or charge significantly higher premiums based on health. New York, Connecticut, and Massachusetts guarantee issue year-round; in all other states, your 6-month window is the one opportunity to lock in comprehensive coverage at standard rates. Missing it without special circumstances is one of the more expensive Medicare enrollment mistakes.
Federal law standardizes Medigap benefits: every plan with the same letter (e.g., Plan G) provides identical coverage regardless of which insurer sells it — only premium and service quality differ. This standardization applies to Original Medicare enrollees; Medigap cannot be used alongside Medicare Advantage, because MA replaces Original Medicare rather than supplementing it. Since Plan F closed to new enrollees in 2020, Plan G has become the dominant choice for new Medigap enrollees. It covers the Part A hospital deductible, Part B coinsurance (20% of all covered services — no annual cap), Part B excess charges, skilled nursing coinsurance, and 80% of foreign travel emergency costs, leaving you responsible only for the annual Part B deductible (~$257 in 2026). Plan G typically runs $150–$250/month depending on age, location, and insurer — converting Original Medicare's unlimited cost exposure to a predictable monthly premium.
How It Affects You
If you're turning 65 and enrolling in Medicare: Your Medigap open enrollment window — 6 months from the date you're both 65+ AND enrolled in Part B — is the single most important insurance timing decision of your Medicare life. During this window, insurers must sell you any plan regardless of health history, and they cannot charge you a higher premium for pre-existing conditions. Once this window closes, underwriting applies in most states. A 65-year-old with diabetes or heart disease who misses this window could be denied coverage or quoted premiums 2-3x higher than a healthy peer — or both. Don't miss it.
If you're choosing a Medigap plan — Plan G is the right starting point for most people: Since Plan F closed to new enrollees after 2020, Plan G covers everything Medicare doesn't — except the Part B annual deductible (~$257 in 2026). A Plan G premium of $150-$250/month may sound high, but compare it to Original Medicare's unlimited exposure: no cap on Part A coinsurance (potentially thousands per day for extended hospital stays), 20% of all Part B-covered services with no annual maximum. One major hospitalization without supplemental coverage can easily exceed $10,000-$30,000 in out-of-pocket costs. Plan G converts that unlimited exposure to a predictable monthly cost.
If you're healthy and rarely see specialists — Plan N is worth considering: Plan N costs roughly $40-$70/month less than Plan G for similar beneficiaries, but requires $20 copays for office visits and $50 for ER visits (waived if admitted), and doesn't cover Part B excess charges (what doctors above Medicare's approved amount can bill you). If you stick with Medicare-participating physicians — who accept Medicare's approved amount as payment in full — excess charges don't arise. Plan N can save $500-$800/year for beneficiaries who rarely use outpatient care.
If you're deciding between Medicare Advantage and Medigap — it's a major fork in the road: If you choose Medicare Advantage instead of Original Medicare, you can't use a Medigap plan. MA plans often have $0 premiums and include drug coverage, but have networks, prior authorization requirements, and cost-sharing that can be unpredictable if you get seriously ill. Medigap + Original Medicare provides more predictable cost exposure and near-universal provider access — relevant if you travel frequently, split time between states, or have ongoing specialist relationships. The choice is hard to reverse: if you switch to MA and later want Medigap, you'll face medical underwriting in most states.
If you're in New York, Connecticut, or Massachusetts: Your state guarantees Medigap issue year-round, not just during the initial enrollment window. This is a significant protection — it means you can switch between Medigap plans or enroll after the initial window without medical underwriting. Most states don't offer this protection.
State Variations
- CT, MA, MN, WI: Use non-standardized Medigap plans with their own benefit structures.
- NY, CT, MA: Guarantee issue year-round (not just the 6-month window). Most states only guarantee issue during the initial enrollment period.
Implementing Regulations
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42 CFR Part 403, Subpart B — Medicare Supplemental Policies: the federal Medigap regulatory framework that state regulators and insurers must follow. Key provisions:
- § 403.205 — State regulatory authority: states are the primary regulators of Medigap insurance; federal standards establish minimum floors that states must meet or exceed; states may impose stricter requirements (Massachusetts, Minnesota, and Wisconsin have their own standardized plan structures that differ from the federal plan letters)
- § 403.206 — Standardized plan requirements: the 10 standard Medigap plan designs (Plans A through N) are defined by CMS; each plan letter corresponds to a specific set of benefits; insurers may not alter the standardized benefit package — Plan G sold by Aetna must cover the same benefits as Plan G sold by UnitedHealth; premium pricing is the only variable across insurers for the same plan letter in the same state
- § 403.210 — Guaranteed issue rights: insurers must issue any standardized Medigap plan to an eligible individual during specified guaranteed issue periods without medical underwriting; key guaranteed issue triggers include: (1) enrollment in Medicare Part B for the first time (6-month open enrollment window, the most important); (2) involuntary loss of employer retiree coverage; (3) loss of Medicare Advantage plan coverage due to plan withdrawal or move out of service area; (4) plan insolvency; outside guaranteed issue periods, insurers in most states can deny or rate-up based on health status
- § 403.215 — Community rating option: states may require community rating (all individuals pay the same premium regardless of age) as an alternative to the attained-age rating that most states allow; New York requires community rating for all Medigap plans
- § 403.230 — Prohibited practices: insurers may not cancel or non-renew a Medigap policy as long as premiums are paid; no policy may impose pre-existing condition exclusions longer than 6 months (and this exclusion is waived if the beneficiary had prior continuous coverage under a defined period); no sale of duplicate coverage to someone already enrolled in a Medigap plan
- § 403.260 — Disclosure requirements: policy must include a standardized Outline of Coverage showing benefit-by-benefit what is covered and the premium; insurers must mail annual rate increase notices and policy anniversary reminders
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NAIC Model Regulation — Model Regulation to Implement the NAIC Medicare Supplement Insurance Minimum Standards Model Act (adopted by reference in federal standards)
Pending Legislation
- HR 610 (Rep. Doggett, D-TX) — Close the Medigap Act of 2025: would expand Medigap guaranteed issue rights, restore first-dollar coverage, limit discriminatory pricing, improve Plan Finder data, and require annual broker payment transparency. Status: Introduced.
- HR 6951 — Stop Unfair Medicaid Recoveries Act: would bar states from recovering correctly paid Medicaid and require notice to beneficiaries and estates (related: affects dual-eligible beneficiaries choosing between Medigap and Medicaid). Status: Introduced.
Recent Developments
- IRA $2,000 Part D cap reduces Medigap's drug-coverage value proposition (2026): The Inflation Reduction Act's $2,000 cap on Part D out-of-pocket drug costs (effective 2026) reduces a key reason seniors historically supplemented Medicare with Medigap — protecting against catastrophic prescription costs. Medigap policies do not cover Part D drug costs (those require separate Part D enrollment), but the IRA cap reduces overall Medicare out-of-pocket exposure. The residual Medigap value proposition remains strong for Part A and B gaps: the $1,676 Part A deductible (2026), the Part B 20% coinsurance on physician and outpatient services, and skilled nursing coinsurance days 21-100 ($209.50/day in 2026) are all covered by standard Medigap plans.
- Medicare Advantage enrollment pressure on Medigap: Medicare Advantage (MA) enrollment now covers approximately 54% of Medicare beneficiaries as of 2026, compared to 42% in 2020. MA's bundled premiums (often $0 premium for basic plans) and additional benefits (dental, vision, hearing, fitness) have drawn beneficiaries away from traditional Medicare + Medigap + Part D combinations. Medigap enrollment has declined as MA has grown. However, beneficiaries who switch from traditional Medicare to MA may find it difficult to return to Medigap — insurers in most states can deny or rate-up Medigap applications based on health status outside open enrollment periods, creating a "lock-in" effect.
- Medigap Plan G dominance and Plan F phase-out: Since 2020, newly eligible Medicare beneficiaries cannot purchase Medigap Plan F (which covered the Part B deductible). Plan G — which covers everything Plan F covered except the Part B deductible ($240 in 2026) — has become the most popular comprehensive Medigap plan. Plan G average premiums range from approximately $120-$200/month depending on age, sex, and state; at a $240 annual Part B deductible, Plan G provides nearly the same coverage as Plan F for less premium cost. High-deductible Plan G ($2,800 deductible in 2026) has gained popularity among healthier beneficiaries seeking lower premiums with catastrophic protection.