Medicare Supplement

How the Medicare Supplement Letter System Works in Lancaster

LANCASTER, Calif. — If you've spent any time shopping for Medicare Supplement coverage, you've probably noticed the alphabet soup: Plan A, Plan G, Plan N, and more. Those letters aren't random. They're part of a federal system designed to make Medigap coverage easier to compare — but only if you know how the system works.

Here's a plain-language look at what Medigap does, how the standardized letters work, and what Lancaster-area readers should watch for before signing anything.

What Medigap actually does

Medigap, also called Medicare Supplement Insurance, is a private policy that works alongside Original Medicare (Part A and Part B). Original Medicare pays its share of covered services, and then your Medigap policy picks up some or all of the leftover costs — things like coinsurance, copayments, and in some cases the Part A hospital deductible.

It's important to know what Medigap is not. It's not Medicare Advantage. You can't have both at the same time. And it does not include prescription drug coverage, so most people with Medigap also enroll in a stand-alone Part D plan.

Why the letters exist

Before the federal government stepped in, Medigap policies were a confusing mess. Two plans with the same name could cover very different things. To fix that, Congress required insurers to sell only standardized plans, each identified by a letter.

Today, in most states, you'll see plans labeled A, B, C, D, F, G, K, L, M, and N. Each letter represents a specific, fixed set of benefits set by federal rules. That means a Plan G sold by one carrier covers the same core benefits as a Plan G sold by another. The premium and customer service may differ, but the benefits inside the letter are the same.

What changed for newer enrollees

If you became eligible for Medicare on or after January 1, 2020, you cannot buy Plans C or F as a new enrollee. That's because those plans covered the Part B deductible, and federal law now prevents new Medigap plans from doing so. People who were already eligible before that date may still have access to them.

For most newly eligible enrollees, Plan G and Plan N are the two most commonly discussed options — but which fits your situation depends on your health, budget, and how you like to pay for care.

The enrollment window that matters most

The single most important date in the Medigap world is the start of your Medigap Open Enrollment Period. This is a six-month window that begins the month you're 65 or older and enrolled in Part B. During this window, you have guaranteed-issue rights: insurers cannot deny you coverage or charge you more because of health conditions.

Miss that window, and in most cases insurers can use medical underwriting. That means they can look at your health history and either raise your rate or turn you down. This is one of the most common — and most expensive — mistakes people make with Medicare.

How Lancaster fits in

Lancaster is in Los Angeles County, where residents have access to a wide range of Medicare options, including Original Medicare with a Medigap policy, Medicare Advantage plans, and stand-alone Part D drug plans. Medigap availability and pricing are regulated at the state level in California, so the letter-based system applies here just as it does elsewhere.

If you're weighing Medigap against Medicare Advantage, remember they work very differently. Medigap pairs with Original Medicare and typically lets you see any provider that accepts Medicare. Medicare Advantage bundles your coverage through a private plan with its own network and rules.

A quick note on 2026 program facts

While Medigap itself doesn't change year to year in dramatic ways, the broader Medicare program does. For 2026, the Part D out-of-pocket cap is $2,100, and the Part D maximum deductible is $615. The old coverage gap, or "donut hole," was eliminated in 2025, and Part D now has three phases. There's also the optional Medicare Prescription Payment Plan, which lets you spread drug costs across the year in monthly payments.

For higher-income enrollees, IRMAA surcharges on Part B and Part D begin above $109,000 in income for a single filer in 2026.

The Annual Enrollment Period runs October 15 through December 7, and the Medicare Advantage Open Enrollment Period runs January 1 through March 31. Note: those windows apply to Part D and Medicare Advantage, not Medigap. Medigap has its own enrollment rules.