Medicare Supplement

Medigap Coverage and Plan Letters for Plainfield Medicare

# Medicare Supplement insurance, explained: what Medigap does and doesn't…

PLAINFIELD, N.J. — If you have Original Medicare, you already know it doesn't pay for everything. There are deductibles, coinsurance, and copays that can add up quickly, especially if you land in the hospital. That's where Medicare Supplement insurance — usually called Medigap — comes in. It's a private policy designed to help pay some of the out-of-pocket costs Original Medicare leaves behind.

Medigap policies sold today are standardized by the federal government and labeled with letters, like Plan A, Plan G, or Plan N. The letters can look confusing at first, but they're actually the key to understanding what you're buying.

What Medigap actually does

Medigap helps pay the "gaps" in Original Medicare — things like the Part A hospital coinsurance, the Part B coinsurance (usually 20%), and, depending on the plan letter, the Part A deductible and other cost-sharing pieces. Some Medigap plans also help with limited emergency care during foreign travel.

What Medigap does not do is stand alone. You need to be enrolled in Medicare Part A and Part B first. Medigap then rides alongside that coverage. Medicare pays its share of an approved service, and your Medigap policy pays some or all of what's left over, based on the letter you chose.

Medigap also doesn't cover prescription drugs, dental, vision, hearing aids, or long-term custodial care. For drug coverage, you'd enroll in a separate Medicare Part D plan.

How the standardized letters work

In most states, Medigap plans come in 10 standardized versions: A, B, C, D, F, G, K, L, M, and N. (Plans C and F are only available if you became eligible for Medicare before January 1, 2020.) Massachusetts, Minnesota, and Wisconsin standardize their plans a little differently.

Here's the important part: because the plans are standardized, Plan G from one insurance company covers the same core benefits as Plan G from another company. What changes from company to company is the monthly premium, customer service, and sometimes small extras. That means comparison shopping is really about price and the company behind the policy, not the benefits list.

Higher-letter plans like G generally cover more and cost more in premium. Lower-letter plans like A or K cover less but usually have lower premiums. There's no single "right" letter — it depends on how much predictability you want in your monthly costs versus your at-the-doctor costs.

Medigap vs. Medicare Advantage — they're not the same thing

This trips up a lot of people. Medicare Advantage (Part C) is a different way to get your Medicare benefits, offered through private plans that bundle Parts A, B, and usually D. Medigap works only with Original Medicare — you cannot use a Medigap policy to pay costs under a Medicare Advantage plan.

So it's really an either/or decision: Original Medicare (often paired with a Medigap policy and a standalone Part D plan) or a Medicare Advantage plan. Plainfield is in Union County, where residents have a range of Medicare Advantage plans available if they go that route, but Medigap availability is a separate question handled by private insurers licensed in New Jersey.

Timing matters: the Medigap Open Enrollment Period

The single most important date in Medigap is your Medigap Open Enrollment Period. It's a one-time, six-month window that starts the first month you're both 65 or older and enrolled in Part B. During that 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 states insurers can use medical underwriting — meaning they can charge you more or deny coverage based on your health. New Jersey has some additional protections, but the safest move is to use that six-month window if you can.

Note that Medigap's enrollment window is different from Medicare's Annual Enrollment Period (October 15 – December 7) and the Medicare Advantage Open Enrollment Period (January 1 – March 31). Those windows are for Advantage and Part D changes, not Medigap.

What to think about before you decide

A few honest questions can help narrow things down:

• Do you travel often, or split time between states? Original Medicare plus Medigap lets you see any doctor in the U.S. who accepts Medicare, with no network.
• Do you want more predictable monthly costs, even if the premium is higher? Higher-letter Medigap plans lean that way.
• Are you comfortable managing two policies (Medigap plus a separate Part D plan)?
• Have you looked at how a Part D plan would fit in? For 2026, Part D has a $2,100 annual out-of-pocket cap on covered drugs, a maximum deductible of $615, and the old "donut hole" coverage gap has been eliminated. There's also an optional Medicare Prescription Payment Plan that lets you spread drug costs across the year.
• Higher-income enrollees should know IRMAA surcharges on Part B and Part D begin above $109,000 in income for a single filer in 2026.

For personalized help, New Jersey's State Health Insurance Assistance Program (SHIP) offers free, unbiased counseling — a good stop before you sign anything.