Why Medigap Uses Letters
Medicare Supplement (Medigap) plans are standardized by the federal government and labeled with letters. The crucial thing this standardization means: a Plan G from one insurer covers exactly the same benefits as a Plan G from any other insurer. The only differences between two identical-letter plans are price and the company's service — which is why comparison shopping across carriers matters so much, a point we make in our Plan G vs. Plan N guide.
There are ten letters in use, but you don't need to memorize all of them. In practice, most people choosing Medigap today land on one of two or three, and several older letters are closed to new enrollees. Here's the full map, then the shortlist that actually matters.
The Plans Most People Actually Choose
For someone new to Medicare, the realistic choices come down to three:
- Plan G: the most popular comprehensive plan. Covers essentially everything except the Part B deductible ($283 in 2026). Predictable, thorough coverage for one modest annual deductible
- Plan N: a lower-premium alternative. Covers most gaps but leaves small copays for some office and ER visits, plus the Part B deductible and any 'excess charges' — a trade-off we detail in our [Plan G vs. Plan N comparison](/blog/medigap-plan-g-vs-plan-n)
- High-Deductible Plan G: a much lower premium in exchange for a high annual deductible (several thousand dollars) before coverage begins — essentially catastrophic Medigap coverage for the healthy
The Other Letters (and Why They're Less Common)
The remaining letters serve narrower needs or are closed to newcomers. Plans A and B offer more basic coverage. Plans K and L cap your out-of-pocket costs but cover a lower percentage of expenses, trading completeness for lower premiums. Plan M splits the difference on deductibles. And Plans C and F — once the most popular because they covered the Part B deductible — are closed to anyone who became Medicare-eligible in 2020 or later, a change we explain in why you can't buy Plan F anymore.
If you became eligible before 2020, you can still buy or keep Plans C and F, but even then Plan G often costs less for nearly identical coverage. For the vast majority of people, the decision is Plan G versus Plan N, with High-Deductible G as a budget option.
How to Actually Choose a Letter
Start by picking the coverage level that fits your risk tolerance and budget — comprehensive (G), lower-premium-with-small-copays (N), or catastrophic (High-Deductible G). Then, and this is the step that saves the most money, compare the price of that exact letter across every carrier available where you live. Because the coverage is identical, you're shopping purely on premium and the insurer's rate-increase history — and premiums for the same Plan G can vary by hundreds of dollars a year between companies.
One more factor: how the insurer prices your plan over time, which we cover in why Medigap premiums rise. The lowest premium today isn't always the best value if it rises fastest. Sorting all of this — the right letter, the right carrier, and the pricing method — is exactly what an independent agent does for you at no cost. Our Advantage vs. Medigap comparison helps if you're still deciding between the two paths entirely.
Frequently Asked Questions
Which Medigap plan is best?
There's no single best plan, but Plan G is the most popular comprehensive choice for people new to Medicare, and Plan N offers a lower premium in exchange for small copays. The 'best' one depends on your budget and how you use care.
Do all insurers charge the same for the same Medigap letter?
No — and this is the key money-saving insight. A Plan G is identical coverage no matter who sells it, but premiums vary significantly between carriers. Always compare the same letter across multiple companies.
Can I still get Medigap Plan F?
Only if you became eligible for Medicare before January 1, 2020. Plans C and F are closed to newer beneficiaries because they covered the Part B deductible, which newer plans are barred from doing. Plan G is the closest available alternative.
What's the difference between Plan G and High-Deductible Plan G?
They cover the same benefits, but High-Deductible Plan G has a much lower premium and a high annual deductible (several thousand dollars) you pay before coverage kicks in. It suits healthy people who want catastrophic protection at a low monthly cost.
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