Medigap (Medicare Supplement) for Solo Seniors: Filling the Gaps in Coverage

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I’ll be blunt — the first time I tried to read about Medigap I closed the tab. Ten letters, ten prices, and a voice on the phone telling me Plan G was “the one everybody picks.” I live alone. Nobody at the table to argue it through with me.

Here is the short answer. Medigap is private insurance that pays the part of Original Medicare you would otherwise pay yourself — the 20% coinsurance with no ceiling on it, the Part A deductible, the Part B deductible. It does not replace Medicare. It sits behind it and picks up what Medicare leaves. You still pay your Part B premium, and you still buy a separate Part D plan, because policies sold since 2006 cannot include drug coverage. I have watched neighbours assume their supplement covered their pills. It does not.

What Medigap Actually Pays For — and Four Things It Never Touches

Part A handles the hospital, Part B the doctor. Neither has an out-of-pocket maximum. That missing ceiling is the whole reason Medigap exists.

Medicare pays 80% of the approved amount for most Part B services. You pay the other 20%. Twenty percent sounds small until you do the arithmetic: Medicare approves $9,000 for a course of treatment, your share is $1,800 — and there is no point at which Medicare says “that’s enough.”

Plans F and G pay that 20% in full. Plan N pays it minus a copay of up to $20 for office visits and $50 for an ER visit that doesn’t end in admission. Plan K pays half, Plan L pays 75%. Those percentages are fixed by law, not by the insurer — which is why comparing letters is easier than comparing companies.

And the part nobody puts in bold: no Medigap plan at any letter covers long-term custodial care, routine dental, routine vision and hearing, or private-duty nursing. I have met people who learned that the hard way.

The Letters: Plans A Through N Without the Sales Pitch

Every Medigap plan with the same letter covers the same basic benefits, no matter which company sells it. Plan G from one insurer covers exactly what Plan G from another covers. Federal standardization guarantees it. So your decision splits into two smaller ones: which letter, then which company.

Plan	Part B coinsurance	Part A deductible	Part B deductible	Out-of-pocket cap	Foreign travel
A	100%	No	No	None	No
B	100%	Yes	No	None	No
G	100%	Yes	No	None	80%
N	100% less copays	Yes	No	Copays only	80%
K	50%	50%	No	Yes	No
L	75%	75%	No	Yes, lower	No
High-deductible G	After deductible	Yes	No	None	80%

Two letters you will see all over older web pages and probably cannot buy: C and F. Since January 1, 2020, both — including high-deductible F — have been closed to anyone who became eligible for Medicare on or after that date. Eligible before 2020? Still sold to you. That is why so much online is quietly out of date: the most-quoted plan on the internet is one most of us cannot buy. Medigap also covers one person — no family policy, so spouses each need their own. And Massachusetts, Connecticut and Minnesota standardize differently.

When You Can Buy Medigap Without Answering a Single Health Question

This matters more than the letters.

You get a six-month Medigap Open Enrollment Period. It starts the month you are both 65 or older and enrolled in Part B. During those six months an insurer must sell you any policy it offers, at the same price it charges a healthy person. No health questions. No exclusions. No surcharge for the arthritis, the diabetes, the stent.

Miss that window and you are in medical underwriting. The company can decline you, charge you more, or refuse to pay for a pre-existing condition for up to six months. I have heard from readers turned down over a medication they had taken for a decade. The window is worth more than any plan letter.

Outside it there are narrow guaranteed issue rights — cases where the company still has to take you at the standard price. Employer coverage that paid secondary to Medicare ends. Your Medicare Advantage plan leaves your area. You usually get 63 days, and the clock starts on a date printed in a letter. Medicare spells this out on its page on when you can buy Medigap.

One thing I got wrong for years: work past 65 and delay Part B, and your six-month window has not started. It is tied to Part B enrollment, not your birthday.

What Medigap Costs, and Why Your Neighbour Pays Less

Two people on the same street, same age, same letter, premiums different by $80 or $100 a month. Three rating methods explain most of it.

Community-rated: everyone pays the same. Issue-age-rated: your price is set by your age when you buy, so it stays comparatively low later. Attained-age-rated: starts cheap and climbs with every birthday — usually the lowest number on the page at 65, and frequently the most expensive by 78.

I ran all three. The attained-age policy was about $40 a month cheaper that first year. Projected over fifteen years it was the priciest by a wide margin. I went with issue-age, though I was making a quiet bet on my own longevity.

What helped more than any spreadsheet was low-tech. I keep one large-print notebook and every January write down the month, the premium, and the percentage increase. One line a year. After four years you can see which companies raise rates gently and which spike. Brochures only show year one.

I keep the paperwork in a plain accordion document organizer, plan letter on each tab.

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Who Should Skip Medigap Entirely

You are in Medicare Advantage and content there. You cannot hold both. It is against the rules for an agent to sell you a Medigap policy while you are enrolled in an Advantage plan unless you are genuinely leaving it. If someone pushes, report it to your State Health Insurance Assistance Program.

The premium does not fit your budget. A supplement that eats 15% of your monthly income and makes you skip a refill is worse than no supplement. Some people manage the 20% with a savings buffer instead.

Medicaid already covers your cost-sharing. Paying twice for coverage you hold is setting money on fire.

Medigap is one piece of a larger stack that also includes Part D and possibly long-term care. The pieces interact in ways nobody warns you about, which is why I worked through it all in my complete insurance guide for solo seniors.

Questions I Wish I Had Asked Before I Signed

Three. I asked two.

Which rating method is this quote? Ask in writing. If the answer is vague, that is the answer.

What was last year’s increase on this exact policy? Not the company average. This policy.

Can I switch later? Most states let you change Medigap policies any time of year — but switching outside your open enrollment window usually means underwriting again, and the health questions come back. A few states have birthday rules that make it far easier.

I keep the plan-by-plan detail — which letters cover foreign travel emergencies, how the three standardizing states differ — on my Medigap guide.

Some of the links on this page are partner links, and I may earn a commission if you purchase through them — at no extra cost to you.

Ready to compare real quotes? Start with our Medigap comparison hub.

Where I checked the facts: medicare.gov on Medigap, when you can buy Medigap, medicare.gov on Medicare costs, and the CFPB’s fraud pages.

Last reviewed: October 2026. Plan availability, guaranteed-issue rules and premiums change yearly and vary by state. Confirm details on medicare.gov or with your State Health Insurance Assistance Program before you enroll.