Medicare 2026

Medicare Supplement (Medigap) Plans for 2027: The Letters, the Rules and When to Buy

Medigap can feel like alphabet soup. The letters, the enrollment windows, and the question of when an insurer can say "no" all matter — and the rules don't change just because the calendar flips to 2027. Here is a plain-English tour of how Medigap works nationally, so you can decide whether it fits your situation.

What Medigap is — and isn't

Medicare Supplement Insurance, better known as Medigap, is private insurance that helps pay some of the out-of-pocket costs Original Medicare leaves behind, such as coinsurance and copayments. It is sold by private insurers but standardized by federal law in most states, which means a Plan G from one company covers the same things as a Plan G from another. Massachusetts, Minnesota, and Wisconsin standardize their Medigap plans differently, so people in those states will see a different menu.

Medigap only works with Original Medicare (Part A and Part B). You cannot use a Medigap policy with a Medicare Advantage plan. And new Medigap policies do not include prescription drug coverage, so if you want drug coverage you add a stand-alone Part D plan.

The letters: A, B, C, D, F, G, K, L, M and N

In most states, Medigap comes in ten standardized plans identified by letter. Each letter represents a specific package of benefits.

Two letters come with a catch. Plans C and F — including high-deductible Plan F — cannot be sold to anyone who became newly eligible for Medicare on or after January 1, 2020. If you were eligible before that date, you may still be able to buy them where they are offered.

Because benefits for a given letter are identical across insurers, the main things that differ between carriers are the premium and the pricing method. Insurers use community rating, issue-age rating, or attained-age rating, and premiums can also vary by age, area, and the insurer itself.

When you can buy — and when health questions can come in

The single most important window is the Medigap Open Enrollment Period: the six months that begin the first month you are both 65 or older and enrolled in Part B. During this window, an insurer cannot refuse to sell you any Medigap policy it offers, and cannot charge you more because of your health history.

Once that six-month window closes, in most states insurers can use medical underwriting — meaning they can ask health questions and decide whether to offer coverage and at what price — unless you have what's called a guaranteed-issue right (certain situations, such as losing other coverage, that trigger federal protections). Some states layer on additional rights beyond the federal minimum. If you miss your initial window, it's worth checking with Medicare.gov or your state's insurance department to see what protections apply to you.

A common point of confusion: Medicare's Annual Enrollment Period, October 15 – December 7, 2026 for coverage starting January 1, 2027, is not a Medigap enrollment period. It is the window for Medicare Advantage and Part D choices. Medigap has its own timing rules.

Original Medicare + Medigap vs. Medicare Advantage: a neutral look

Many people weigh Original Medicare with a Medigap policy against a Medicare Advantage plan. Both are legitimate paths with different trade-offs.

• Original Medicare + Medigap generally lets you see any provider that accepts Medicare nationwide, and the Medigap policy helps make out-of-pocket costs predictable. You pay a Medigap premium, and you add (and pay for) a stand-alone Part D plan if you want drug coverage.
• Medicare Advantage bundles Part A, Part B, and usually Part D into one plan, often with network rules and extra benefits set by the plan. Costs and benefits are structured differently than with Medigap.

Neither one is "better" in the abstract — it depends on your providers, your budget, your health, and how you like to use coverage.

Drug coverage in 2027: what to know

If you pair Medigap with a stand-alone Part D plan, a few 2027 program numbers are worth filing away. The Part D annual out-of-pocket cap rises to $2,400 (it is $2,100 in 2026). The maximum deductible a Part D plan may charge in 2027 is $700. And the national Part D base beneficiary premium — a figure used in calculating the late-enrollment penalty, not what any one plan charges — is $41.33.

If you have Medicaid or Extra Help, since 2025 you have a monthly Special Enrollment Period to move to Original Medicare with a stand-alone Part D plan, or to switch stand-alone Part D plans. Full-benefit dual-eligible individuals can join an integrated D-SNP in any month.

A couple of 2027 numbers that are not out yet

The 2027 Part B standard premium and deductible have not been announced, and neither have the 2027 income-related monthly adjustment amount (IRMAA) brackets. CMS typically announces these in the fall. Social Security did announce, on October 14, 2026, a 3.6 percent cost-of-living adjustment for benefits payable beginning January 2027.

Where to go next

For official plan details, Medigap policy finder tools, and the current rules, visit Medicare.gov or call 1-800-MEDICARE (1-800-633-4227), TTY 1-877-486-2048. Taking a little time now — before the next enrollment deadline or before a six-month window closes — can save a lot of second-guessing later.

This article is educational and is published by a privately owned Medicare education site. It is not affiliated with or endorsed by the federal government or Medicare.