Medicare Supplement

How Medigap Letter Plans Work for Duncan Medicare Readers

DUNCAN, Okla. — If you've ever looked at a Medicare Supplement brochure and felt lost in a sea of letters — Plan A, Plan G, Plan N — you're not alone. Medigap policies use a lettering system that can feel like alphabet soup, but it's actually designed to make shopping easier, not harder. Here's a plain-language look at what Medigap does, how the letters work, and what Duncan-area readers should know before Medicare's next enrollment window.

What Medigap Actually Does

Medicare Supplement Insurance — nearly always called Medigap — is a private policy that works alongside Original Medicare (Part A and Part B). It helps pay some of the out-of-pocket costs Original Medicare leaves behind, such as coinsurance, copayments, and, with some policies, the Part A hospital deductible.

A few important points from Medicare.gov:

• Medigap only works with Original Medicare. It does not pair with a Medicare Advantage plan.
• Medigap policies generally do not include prescription drug coverage. For drugs, you'd add a stand-alone Part D plan.
• You pay a monthly premium to the private insurance company in addition to your Part B premium.

Medigap doesn't replace Medicare — it fills in gaps in what Medicare pays.

Why the Letters Exist

Here's the part that trips people up. In most states, Medigap plans are standardized by the federal government. That means Plan G sold by one company covers the exact same benefits as Plan G sold by another company. Same for Plan N, Plan K, and the rest.

What changes between carriers is:

• The monthly premium
• Customer service and reputation
• How the company rates premiums (by age, community, etc.)

So the letter tells you what's covered. The company tells you how much you'll pay for that coverage and who you'll deal with.

The Plans Available Today

As of 2020, Plans C and F are no longer sold to people who are newly eligible for Medicare. That's because those plans covered the Part B deductible, and Congress phased that out for new enrollees. If you were eligible for Medicare before January 1, 2020, you may still be able to buy or keep them.

The plans currently offered to new enrollees include A, B, D, G, K, L, M, and N. Plan G and Plan N are among the most talked-about because they offer broader coverage, but the "right" letter depends entirely on your health, budget, and how often you use care. Medicare.gov offers a side-by-side benefit chart that shows exactly what each letter covers.

Massachusetts, Minnesota, and Wisconsin standardize their Medigap plans a little differently — but in Oklahoma, the federal letter system applies.

Enrollment Timing Matters — A Lot

The best time to buy a Medigap policy is during your Medigap Open Enrollment Period: the six months that begin the first month you're 65 and enrolled in Part B. During that window, insurance companies can't turn you down or charge you more because of health problems.

Outside that window, in most states — including Oklahoma — insurers can use medical underwriting. That means they can ask about your health and potentially deny coverage or raise your premium. This is one of the biggest reasons Medicare experts urge people to look at Medigap carefully when they first become eligible.

Keep in mind, Medigap enrollment is separate from the annual periods you may hear about on TV:

• Medicare Annual Enrollment Period: Oct. 15 – Dec. 7 (for Part D and Medicare Advantage changes)
• Medicare Advantage Open Enrollment: Jan. 1 – March 31

Those windows don't guarantee Medigap access.

How This Connects to Duncan

Duncan is in Stephens County, where local Medicare beneficiaries have both Original Medicare (with the option to add Medigap) and Medicare Advantage plans available. Availability of Medicare Advantage plans is set at the county level, but Medigap is regulated at the state level, so the letter system and consumer protections in Oklahoma apply the same in Duncan as they do elsewhere in the state.

If you already have a Medicare Advantage plan and are curious about Medigap, remember: you can't use both at the same time. Switching between them is a bigger decision than swapping Advantage plans, so it's worth talking to a trusted, unbiased counselor first.

A Quick Note on 2026 Costs

Medigap is separate from Part D drug coverage, but many people carry both. A few 2026 figures worth knowing:

• The Part D out-of-pocket cap is $2,100 for 2026.
• The Part D maximum deductible is $615.
• The old "donut hole" coverage gap was eliminated in 2025; Part D now has three phases.
• The Medicare Prescription Payment Plan lets you spread drug costs across the year in monthly installments if you choose.
• IRMAA income-related surcharges for Part B and Part D begin above $109,000 for a single filer in 2026.