Medicare Supplement

How Federal Rules Standardize Medigap Letters in Hilo

HILO, Hawaii — If you're on Original Medicare and looking at ways to handle the out-of-pocket costs it doesn't cover, you've probably run into a wall of letters: Plan A, Plan G, Plan N, Plan K. These are Medicare Supplement plans — better known as Medigap — and the letters aren't random. They're standardized by the federal government, which makes shopping a lot less confusing once you know how the system works.

Making sense of Medigap in Hilo

Here in Hilo, part of Hawaii County, many neighbors ask the same question: what does Medigap actually do, and how do I figure out which letter fits my life? Let's walk through it in plain language.

What Medigap is — and what it isn't

Medigap is private insurance that works alongside Original Medicare (Part A and Part B). After Medicare pays its share of a covered service, your Medigap policy picks up some or all of what's left — things like coinsurance, copayments, and in some cases the Part A and Part B deductibles.

A few important points from Medicare.gov:

• Medigap only works with Original Medicare. You cannot use a Medigap policy with a Medicare Advantage plan.
• Medigap does not include prescription drug coverage. If you want drug coverage, you'd add a stand-alone Part D plan.
• You pay a monthly premium for Medigap on top of your Part B premium.
• Each Medigap policy covers one person. Spouses need their own policies.

Medigap is designed for people who want predictable costs and the freedom to see any provider in the U.S. that accepts Medicare — helpful if you split time between Hilo and the mainland, or travel to Oahu for specialty care.

How the standardized letters work

In most states, Medigap plans come in ten standardized versions, each labeled with a letter: A, B, C, D, F, G, K, L, M, and N. (Plans C and F are only available to people who became eligible for Medicare before January 1, 2020.)

Here's the key idea: every plan with the same letter offers the exact same core benefits, no matter which insurance company sells it. A Plan G from one carrier covers the same gaps as a Plan G from another carrier. What can differ is the price and the customer service.

That makes comparing plans much simpler than it looks. Once you decide which letter fits your needs, you're mostly comparing premiums and the reputation of the company behind the policy.

Note: Hawaii follows the standard federal Medigap structure. (Massachusetts, Minnesota, and Wisconsin use their own systems.)

How to think about choosing a letter

Instead of starting with the letter, start with the question: how much risk do I want to carry myself, versus pay for in a premium?

• Plans that cover more of your out-of-pocket costs generally have higher monthly premiums.
• Plans that leave more costs on you — like plans with a deductible or copays for certain visits — tend to have lower premiums.
• Some letters are aimed at people comfortable with higher cost-sharing in exchange for lower monthly costs.

There's no single "right" letter. A retiree in Hilo who rarely sees a doctor may weigh the tradeoffs very differently than someone managing a chronic condition who visits specialists often.

The enrollment window that matters most

The best time to buy a Medigap policy is during your Medigap Open Enrollment Period — the six months that start the month you're 65 or older and enrolled in Part B. During this window, insurance companies must sell you any Medigap policy they offer at their best available rate, regardless of your health history.

Outside that window, in most cases, insurers can use medical underwriting. That means they can charge more, or turn you down, based on your health. This is different from the fall Annual Enrollment Period (Oct. 15 – Dec. 7), which is for Medicare Advantage and Part D — not Medigap.

Medigap and your drug coverage

Because Medigap doesn't cover prescriptions, most people pair it with a stand-alone Part D plan. A few 2026 facts worth knowing:

• The Part D out-of-pocket cap is $2,100 in 2026. Once you hit it, you pay $0 for covered drugs the rest of the year.
• The maximum Part D deductible is $615.
• The old "donut hole" is gone as of 2025 — Part D now has three phases.
• The Medicare Prescription Payment Plan lets you spread your drug costs across the year in monthly amounts instead of paying big bills at the pharmacy.
• IRMAA — an income-based surcharge on Part B and Part D — starts above $109,000 for single filers in 2026.