Medicare Supplement

Mililani guide to Medigap and Original Medicare gaps

If you live in Mililani and you're sorting through Medicare mail, chances are you've seen the word "Medigap" more than once. Medicare Supplement insurance — often called Medigap — is a type of private coverage designed to work alongside Original Medicare (Part A and Part B). It helps pay for some of the costs Original Medicare leaves behind, like coinsurance, copayments, and deductibles.

Medicare Supplement insurance in plain English

Medigap is not the same as a Medicare Advantage plan, and it's not a drug plan. It's a companion policy. Original Medicare pays its share first, and your Medigap plan picks up part — or in some cases most — of what's left. That's the whole job.

How the standardized letters work

Here's the part that trips people up: Medigap plans come in standardized types identified by letters — A, B, C, D, F, G, K, L, M, and N. In most states, every insurer that sells "Plan G," for example, has to offer the exact same core benefits under Plan G. The letter tells you what's covered. The insurance company sets the price and handles the service.

That means if two carriers both sell Plan N, the benefits are identical by law, even if the monthly premium is different. You're comparing companies and prices, not benefit charts.

A few things worth knowing:

• Plans C and F are only available to people who became eligible for Medicare before January 1, 2020.
• Plans K and L have lower premiums but higher out-of-pocket shares.
• Massachusetts, Minnesota, and Wisconsin standardize their Medigap plans differently.
• Hawaii, including Mililani, follows the standard federal lettering system.

For the official benefit grid, Medicare.gov publishes a side-by-side chart of what each letter covers.

What Medigap does — and doesn't — do

What Medigap generally helps with:

• Part A hospital coinsurance and extra hospital days
• Part B coinsurance or copayments
• Blood (first three pints)
• Hospice care coinsurance
• Skilled nursing facility coinsurance (on some letters)
• Part A and Part B deductibles (on some letters)
• Foreign travel emergency care (on some letters)

What Medigap does not cover:

• Prescription drugs (you'd need a separate Part D plan)
• Dental, vision, or hearing care
• Long-term care (nursing home stays for custodial reasons)
• Private-duty nursing
• Eyeglasses or hearing aids

Because Medigap doesn't include drug coverage, most people pair it with a stand-alone Part D plan.

How Medigap fits with Part D in 2026

If you have Original Medicare plus a Medigap plan, you'll usually add a Part D drug plan to cover medications. A few 2026 figures worth writing down:

• The Part D out-of-pocket cap is $2,100 for 2026. Once you hit it, you pay $0 for covered drugs the rest of the year.
• The Part D maximum deductible is $615.
• The old "donut hole" coverage gap is gone — as of 2025, Part D has three phases, not four.
• The Medicare Prescription Payment Plan lets you spread drug costs into monthly payments instead of paying big amounts at the pharmacy counter.
• IRMAA surcharges (extra premiums for higher earners) start above $109,000 in income for a single filer in 2026.

These figures come from CMS and Medicare.gov and apply nationwide, including in Honolulu County.

Timing matters: the Medigap Open Enrollment window

The single most important date in Medigap isn't in the fall — it's the six-month window that starts the month you turn 65 and are enrolled in Part B. During that one-time Medigap Open Enrollment Period, insurers must sell you any Medigap policy they offer at their best available rate, regardless of your health history.

Outside that window, in most states, carriers can use medical underwriting. That means they can ask about your health and, in some cases, decline coverage or charge more. There are some guaranteed-issue exceptions (for example, if you lose other coverage), but the six-month window at 65 is the cleanest shot most people get.

This is different from the Medicare Annual Enrollment Period (October 15 – December 7), which is for Part D and Medicare Advantage — not Medigap.

A quick word about local availability

Mililani is in Honolulu County, where residents choose between staying with Original Medicare (often paired with Medigap and a Part D plan) or enrolling in a Medicare Advantage plan. The specific Medigap policies sold in Hawaii are set by the carriers licensed here, and the standardized letters are the same ones offered on the mainland. You can compare the companies selling Medigap in your ZIP code using the plan finder at Medicare.gov.