Retiring at 65 or being laid off after years of employer-sponsored coverage puts you at a crossroads. Medicare Parts A and B cover the basics, but Original Medicare leaves significant gaps: the 20% Part B coinsurance has no cap, the Part A hospital deductible of $1,736 in 2026 resets every benefit period (not once a year), and there is no out-of-pocket maximum. Medigap policies fill those gaps for a predictable monthly premium. The problem: Medigap in most states relies on medical underwriting after your initial enrollment window. Insurers can refuse to sell you a policy, or quote you thousands more per year, if you have diabetes, heart disease, cancer history, or most chronic conditions. The guaranteed-issue right that comes with losing group coverage at 65 is the federal exception that forces insurers to sell you a policy regardless of your health history. Understanding this 63-day window is the single most financially consequential decision you will make during the Medicare transition, and missing it has no remedy except hoping your state has an annual birthday rule.
Federal law under 42 U.S.C. Section 1395ss(s) creates the guaranteed-issue right. The triggering event is losing employer or union group health plan coverage involuntarily (or at retirement) while enrolled in Original Medicare Parts A and B. The 63-day clock starts the day after coverage ends, whichever is earlier: the day coverage actually ends, or the day you receive written notice that coverage will end. Seven plan letters qualify under the federal guaranteed-issue right: Plans A, B, C, D, F, G, K, and L. Note: Plans C and F are closed to anyone first eligible for Medicare on or after January 1, 2020 (they covered the Part B deductible, which Congress banned for new enrollees via MACRA 2015). For 2026 new-to-Medicare enrollees, Plan G is the gold-standard choice, covering everything except the $283 2026 Part B annual deductible. Plan N, while widely marketed, is NOT a federally guaranteed-issue plan in most situations. Apply through a licensed insurance agent or directly through an insurer, not through healthcare.gov (which handles ACA Marketplace, not Medicare Supplement). Use the medicare.gov Plan Finder to compare premiums by ZIP code.
7 Steps to Get Coverage
Common Mistakes That Cost People Thousands
The costliest mistakes people make when losing group coverage at 65 during the Medigap guaranteed-issue window:
- Waiting too long to apply. The 63-day clock is firm. Day 64 and beyond, Medigap insurers in most states can and will ask health questions. Many applicants with common chronic conditions get rated up 25 to 50% or denied entirely.
- Enrolling in Medicare Advantage instead of Medigap without understanding the difference. Medicare Advantage uses provider networks and prior authorization; Medigap works with any Medicare-accepting doctor nationwide. Once you leave Original Medicare for Medicare Advantage, re-entering Medigap requires passing medical underwriting in most states.
- Assuming Plan N carries guaranteed-issue rights. Under federal law, guaranteed-issue applies to Plans A, B, C, D, F, G, K, and L only. Plan N is not on the list. Some states extend guaranteed-issue to Plan N, but most do not. Verify with your state insurance department before banking on Plan N availability.
- Skipping Part D because current prescriptions are affordable. The Part D late enrollment penalty is 1% per month for every month without creditable coverage, permanently added to your premium. Even if you pay $0 out of pocket today, going 12 months without Part D adds roughly 12% to whatever plan you eventually buy, for life.
- Using healthcare.gov to find Medigap. Healthcare.gov handles ACA Marketplace plans, not Medicare Supplement policies. Go to medicare.gov for Medigap plan comparison and the Medicare Plan Finder. Applying through the wrong portal can result in purchasing an ACA plan you cannot use (Medicare beneficiaries cannot receive ACA subsidies).
- Choosing the cheapest Medigap Plan G quote without comparing rating methods. Attained-age rated plans are cheapest at 65 but increase annually; at age 75 the same plan may cost $100 to $200 more per month than a community-rated plan purchased at the same age. Ask the insurer explicitly how their premiums are calculated before signing.
Which Medigap Plans Are Available Under Guaranteed Issue in 2026?
Federal law at 42 U.S.C. Section 1395ss(s) specifies exactly eight Medigap plan letters available under guaranteed-issue rights when you lose group coverage: Plans A, B, C, D, F, G, K, and L. Plans C and F, though on the federal list, are only available to people who were first eligible for Medicare before January 1, 2020 (i.e., turned 65 or qualified by disability before that date). Under the Medicare Access and CHIP Reauthorization Act of 2015 (MACRA), Congress closed Plans C and F to new Medicare enrollees because those plans covered the Part B deductible, which the law determined created incentives for overutilization. For anyone first eligible for Medicare from January 1, 2020 onward, Plan G is the most comprehensive available plan under guaranteed issue. Plan G covers: the Part A hospital deductible ($1,736 per benefit period in 2026), Part A coinsurance and hospital costs up to an additional 365 days after Medicare benefits are exhausted, skilled nursing facility coinsurance, Part B coinsurance (the 20% gap), Part B excess charges (when a provider charges above Medicare's approved amount), and 80% of foreign travel emergency costs. The only uncovered expense: the 2026 Part B annual deductible of $283.
Medigap Plan G vs Plan N vs High-Deductible Plan G: 2026 Coverage Comparison| Benefit | Plan G | Plan N | High-Deductible Plan G |
|---|
| Part A hospital deductible ($1,736 in 2026) | Covered | Covered | Covered after $2,950 deductible |
| Part B coinsurance (20%) | Covered | Covered (copays up to $20 office, $50 ER) | Covered after $2,950 deductible |
| Part B annual deductible ($283 in 2026) | Not covered | Not covered | Not covered (counts toward $2,950) |
| Part B excess charges | Covered | Not covered | Covered after $2,950 deductible |
| Skilled nursing facility coinsurance | Covered | Covered | Covered after $2,950 deductible |
| Foreign travel emergency (80%) | Covered | Covered | Covered after $2,950 deductible |
| Typical monthly premium (age 65, 2026) | $140 to $260 | $100 to $180 | $60 to $80 |
| Guaranteed issue from group coverage loss | Yes (federal right) | Not guaranteed federally; varies by state | Yes (federal right) |
High-Deductible Plan G 2026 deductible: $2,950 (per CMS). Plan N copayments: up to $20 for office visits, up to $50 for ER visits not resulting in admission. Plan N does not cover Part B excess charges. Premium ranges are nationwide estimates for a 65-year-old non-smoker; actual quotes vary by ZIP code and insurer.
Source: medicare.gov Medigap plan benefits comparison, CMS 2026 High-Deductible Medigap deductible announcement
State Birthday Rules: An Annual Second Chance for Medigap Switching in 2026
Federal guaranteed-issue rights are time-limited to the qualifying event window. Most states have no mechanism to switch Medigap plans without medical underwriting after that window closes. However, as of 2026, approximately 16 states have enacted birthday rule laws that grant Medigap enrollees an annual window to switch to a plan with equal or lesser benefits without underwriting. California pioneered the birthday rule, allowing a 60-day window after your birthday each year. Oregon and Washington have similar rules. Nevada allows switching to any Medigap plan without underwriting annually. Missouri, Idaho, Illinois, and Louisiana have variations that permit switching within the same carrier or to plans with equal benefits. Delaware and Indiana joined as of 2026, each allowing 30-day windows around the birthday. Connecticut, Maine, Massachusetts, Minnesota, New York, and Washington use community-rating (same premium regardless of health), which effectively removes underwriting barriers for switches at any time in those states. New Mexico and West Virginia enacted birthday rule legislation in 2025 and 2026 respectively. If you missed the 63-day guaranteed-issue window after losing group coverage, check your state's insurance department website immediately to determine whether your state's birthday rule provides a next available window.
Medigap vs Medicare Advantage: The Coverage-Loss Decision Matrix
Losing group coverage at 65 forces the most consequential insurance decision most people make. Two main paths exist: Original Medicare plus Medigap, or Medicare Advantage. Medigap works with any provider in the US that accepts Medicare, has no provider network, and imposes no prior authorization for covered services. Plan G's predictable cost structure makes it ideal for people with chronic conditions, anyone who travels or splits time between states, and retirees who want the simplicity of knowing exactly what they will pay. Medicare Advantage bundles Parts A, B, and usually D into one plan sold by a private insurer. Most Medicare Advantage plans charge $0 additional premium beyond the $202.90 Part B amount, but this comes with a trade-off: you must use the plan's provider network (except for emergencies), obtain prior authorization for many services, and the plan's in-network out-of-pocket maximum can be as high as $9,250 in 2026. The Medicare Advantage MOOP of $9,250 for 2026 is the federal ceiling; many plans have lower MOOPs. The critical asymmetry: enrolling in Medicare Advantage from the initial guaranteed-issue window is reversible only with medical underwriting in most states. If you enroll in Medicare Advantage at 65 and later want to switch to Medigap, you generally cannot do so without health questions. This makes the guaranteed-issue window after group coverage loss the one moment where choosing Medigap over Medicare Advantage carries no downside risk of being locked out of Medigap later.
Documents Needed to Apply for Medigap Under Guaranteed-Issue Rights
Medigap insurers cannot ask health questions during the 63-day guaranteed-issue window, but they can and do verify that your qualifying event is legitimate. Gathering documents in advance prevents delays that might push you past the 63-day deadline. The most important document is the group coverage termination letter, which must state the date coverage ends and the reason (retirement, job loss, reduction in hours, or employer plan termination). If your employer provides a HIPAA Certificate of Creditable Coverage (required under 29 CFR 2590.701-5 for plans that were creditable), include that too. Your Medicare card or SSA enrollment confirmation letter proves Part B enrollment status. If you delayed Part B while on the employer plan, include documentation of the employer plan (often a letter from HR or a benefits summary page) to confirm you are applying during a valid Special Enrollment Period for Part B. Social Security number is required on all Medigap applications. Your complete mailing address and date of birth are needed for premium rating purposes.
Frequently Asked Questions
How many days do I have to enroll in Medigap after losing group coverage at 65?
You have 63 days from the date your group health plan coverage ends. The clock starts on the day after coverage actually ends (not the day you receive notice). For example, if your employer coverage ends August 31, 2026, your guaranteed-issue Medigap deadline is November 2, 2026. During this 63-day window, any Medigap insurer licensed in your state must sell you Plans A, B, C, D, F, G, K, or L without medical underwriting and at their best available rate.
Which Medigap plans can I get under the guaranteed-issue right when I lose group coverage?
Federal guaranteed-issue rights cover Plans A, B, C, D, F, G, K, and L. However, Plans C and F are only available to people first eligible for Medicare before January 1, 2020, due to MACRA 2015 restrictions. For anyone turning 65 today, Plan G is the most comprehensive option available under guaranteed issue. Plan N is not on the federal guaranteed-issue list, although some states extend guaranteed-issue to Plan N voluntarily. Verify with your state insurance department before relying on Plan N availability.
What if I miss the 63-day Medigap guaranteed-issue window after losing group coverage?
Missing the 63-day window means Medigap insurers in most states can subject you to medical underwriting. Common chronic conditions including diabetes, heart disease, COPD, cancer history, and obesity can result in denial or premium surcharges of 25 to 50%. Your options after missing the window include: enrolling in Medicare Advantage (which must accept all Medicare beneficiaries during enrollment periods), waiting for your state's annual birthday rule window if your state has one, or moving to a community-rated state (Connecticut, Massachusetts, Minnesota, New York, Washington) where underwriting rules differ.
Does losing group coverage at 65 also give me a Special Enrollment Period for Medicare Part B?
Yes. If you had employer group coverage from an employer with 20 or more employees and delayed Part B enrollment, losing that coverage triggers an 8-month Special Enrollment Period for Part B. Note: the 8-month Part B SEP starts when coverage ends or employment ends, whichever comes first. You do not need to wait until the Medicare General Enrollment Period (January 1 to March 31) if you qualify for the Part B SEP. Apply for Part B at SSA.gov or call Social Security at 1-800-772-1213.
What is the difference between Medigap and Medicare Advantage, and which should I choose after losing group coverage?
Medigap (Medicare Supplement Insurance) works alongside Original Medicare Parts A and B to fill cost-sharing gaps. Plan G, the most popular 2026 option, covers nearly everything except the $283 Part B annual deductible, with no provider network and no prior authorization. Medicare Advantage replaces Original Medicare with a private plan that usually has a $0 additional premium but requires using a provider network and obtaining prior authorization for many services. The critical asymmetry: once you choose Medicare Advantage, returning to Medigap requires passing medical underwriting in most states. The guaranteed-issue window is your one opportunity to lock in Medigap without health questions, so switching to Medicare Advantage during this window sacrifices that protection permanently in most states.
Can I get Medigap if I am under 65 and lose group coverage?
Federal law requires Medigap guaranteed-issue rights only for people 65 and older. For people under 65 who qualify for Medicare due to disability or ESRD, guaranteed-issue Medigap access varies by state. Currently only about 26 states require Medigap insurers to sell policies to Medicare beneficiaries under 65. In those states, premiums may be significantly higher than at age 65. Check your state's insurance department website. At 65, even if you previously enrolled in Medigap under age 65, you get a fresh 6-month Medigap Open Enrollment Period when you turn 65 and enroll in Part B.
What happens to my Medigap premiums over time, and how does the rating method affect long-term cost?
Medigap premiums are set by one of three rating methods. Community-rated plans charge everyone the same regardless of age, making them more expensive at 65 but stable over time. Issue-age-rated plans set premiums based on the age when you first buy the policy and increase only for inflation. Attained-age-rated plans start lowest at 65 but increase every year as you age, often by 3 to 8% annually. At age 75 or 80, attained-age plans can cost $100 to $200 per month more than community or issue-age plans purchased at the same initial age. The guaranteed-issue window is the best time to compare all three rating methods across multiple carriers. Ask explicitly: how is your premium calculated and by what method does it increase annually?
What state-specific rules expand Medigap guaranteed-issue rights beyond the federal minimum?
Several states extend guaranteed-issue or underwriting protections beyond federal law. Community-rated states (Connecticut, Massachusetts, Minnesota, New York, Washington) price all Medigap policies at the same rate regardless of health, effectively making underwriting irrelevant. States with birthday rules (California, Oregon, Nevada, Idaho, Missouri, Louisiana, Illinois, Delaware, Indiana, and others as of 2026) allow annual Medigap plan switches without underwriting in a window around your birthday. Some of these states extend guaranteed-issue to Plan N, which has no federal guarantee. State rules change frequently; verify with your State Health Insurance Assistance Program (SHIP) counselor, which provides free advice through the medicare.gov SHIP directory.
