Medicare Supplement

Medigap Plan Letters, Explained for Indianapolis Retirees

If you have Original Medicare (Part A and Part B), the program pays a big share of your covered hospital and doctor bills — but not all of it. You're still on the hook for deductibles, coinsurance, and some copays, and there's no yearly cap on what those out-of-pocket costs can add up to.

What Medigap actually does

That's the gap a Medicare Supplement policy — often called Medigap — is designed to help fill. You pay a monthly premium to a private insurance company, and in return the policy pays some or all of the leftover costs that Original Medicare doesn't cover.

Medigap only works with Original Medicare. If you're enrolled in a Medicare Advantage plan (Part C), you can't use a Medigap policy alongside it.

Why the letters exist

Here's the part that trips people up: Medigap policies are sold by lots of different companies, but the benefits inside each plan are standardized by the federal government. That means a Plan G from one insurer covers the exact same Medicare cost-sharing items as a Plan G from any other insurer.

The letters — A, B, C, D, F, G, K, L, M, and N — identify which package of benefits the policy includes. (Massachusetts, Minnesota, and Wisconsin standardize their plans differently, but Indiana uses the federal letter system.)

Because the benefits are set by law, the main things that vary between two policies with the same letter are:

• The monthly premium
• The company's customer service and billing
• How the company sets future rate increases

How the letters compare

Each lettered plan covers a different mix of the following: Part A hospital coinsurance, Part B coinsurance, the first three pints of blood, hospice coinsurance, skilled nursing facility coinsurance, the Part A deductible, the Part B deductible, Part B excess charges, and foreign travel emergency care.

A few quick facts worth knowing:

• Plans C and F cover the Part B deductible, but they are only available to people who became eligible for Medicare before January 1, 2020. If you turned 65 after that date, they're off the table.
• Plan G is the closest replacement for Plan F for newer enrollees — it covers nearly the same things except the Part B deductible.
• Plans K and L have lower premiums but come with an out-of-pocket limit and cost-sharing on many benefits.
• Plan N has lower premiums than G in exchange for small copays at office and ER visits, and it doesn't cover Part B excess charges.

The official side-by-side comparison chart is on medicare.gov.

What Medigap does not do

Medigap policies don't include prescription drug coverage. If you want drug coverage, you'd add a separate Part D plan. In 2026, Part D has a $2,100 annual out-of-pocket cap, a maximum deductible of $615, and an optional Medicare Prescription Payment Plan that lets you spread drug costs across the year in monthly amounts.

Medigap also doesn't cover routine dental, vision, hearing aids, or long-term custodial care.

When you can buy one in Indianapolis

Indianapolis is in Marion County, and Indiana follows federal Medigap rules. Your best window to buy is your Medigap Open Enrollment Period — the six months that start the month you're 65 or older and enrolled in Part B. During that window, insurers can't turn you down or charge you more because of your health history.

Outside that window, in most cases, companies in Indiana can use medical underwriting, which means your health can affect whether you're accepted and what you pay. There are a few limited "guaranteed issue" situations, such as losing certain other coverage.

The Annual Enrollment Period (Oct. 15 – Dec. 7) and the Medicare Advantage Open Enrollment Period (Jan. 1 – March 31) are for Medicare Advantage and Part D changes — they are not Medigap enrollment windows.

How to decide which letter fits

A few honest questions to work through:

1. How much predictability do you want? Plans like G tend to have higher premiums and lower surprises. Plans like K, L, or N have lower premiums and more cost-sharing. 2. When did you become Medicare-eligible? That determines whether C and F are even options. 3. Do you travel abroad often? Several letter plans include foreign travel emergency coverage; a few don't. 4. What's your budget for a monthly premium versus paying at the point of care?

Once you know which letter fits your situation, then you can shop the premium among companies selling that same letter in your ZIP code.