Medicare Supplement

The federal system behind Medigap letters in Trenton

TRENTON, N.J. — If you've ever tried to shop for a Medicare Supplement policy, you've probably run into a wall of letters: Plan A, Plan B, Plan G, Plan N. It can feel like alphabet soup. The good news is that these letters follow a clear, federally standardized system — once you understand how it works, comparing options gets a lot simpler.

Here's a plain-language guide to what Medigap does, how the letters work, and where Trenton-area readers can go for personalized help.

What Medigap actually is

Medigap, also called Medicare Supplement Insurance, is a private policy that works alongside Original Medicare (Part A and Part B). It helps pay some of the out-of-pocket costs Original Medicare leaves behind — things like coinsurance, copayments, and deductibles.

A few important points, according to Medicare.gov:

• Medigap only works with Original Medicare. You can't use it with a Medicare Advantage plan.
• It doesn't include prescription drug coverage. For that, you'd add a separate Part D plan.
• You pay a monthly premium to the private insurer, on top of your Part B premium.

Medigap is designed to bring predictability to your health spending. It won't cover everything — for example, most policies don't help with dental, vision, hearing aids, or long-term care — but it can smooth out the bumps of Original Medicare's cost-sharing.

Why the letters exist

Before the 1990s, Medigap policies were a confusing mess. Every insurer offered different benefits, and shoppers had a hard time comparing them side by side. So Congress required that Medigap plans be standardized.

Today, in most states — including New Jersey — Medigap policies come in ten standardized options identified by letters: A, B, C, D, F, G, K, L, M, and N. (Massachusetts, Minnesota, and Wisconsin use their own systems.)

Here's the key idea: A Plan G from one insurance company covers the exact same benefits as a Plan G from any other company. The federal government sets what each lettered plan must include. Insurers can only compete on price, customer service, and extras — not on the core benefits.

That's a big deal for shoppers. It means if two companies both sell Plan N, you're comparing apples to apples on coverage.

A quick tour of the letters

Every Medigap plan covers a base set of benefits, like Part A hospital coinsurance. Beyond that, the letters cover different combinations of:

• Part B coinsurance and copayments
• The first three pints of blood
• Hospice care coinsurance
• Skilled nursing facility coinsurance
• Part A and Part B deductibles
• Part B excess charges
• Foreign travel emergency care

Some plans, like Plan A, cover the basics only. Others, like Plan G, cover nearly everything except the Part B deductible. Plans K and L are lower-premium options that use cost-sharing — you pay a percentage until you hit an annual out-of-pocket limit. Plan N covers most costs but asks for small copays at office and ER visits.

One important note about newer enrollees: If you became eligible for Medicare on or after January 1, 2020, you cannot buy Plans C or F. Those two plans covered the Part B deductible, and federal law now prohibits new Medigap policies from doing that. People who were already eligible before 2020 can still buy or keep them.

Why timing matters — the Medigap open enrollment window

Here's where a lot of people get tripped up. Unlike Medicare Advantage or Part D, Medigap doesn't have a yearly enrollment period tied to the fall calendar.

Instead, your best window is your six-month Medigap Open Enrollment Period, which starts the month you're 65 or older and enrolled in Part B. During this one-time window, insurers must sell you any Medigap policy they offer at their best available rate, regardless of your health history.

After that window closes, in most states insurers can use medical underwriting — meaning they can charge you more or turn you down based on your health. New Jersey has some additional consumer protections, but the safest time to shop is during that initial six months.

How this fits with the rest of Medicare

Medigap is one piece of the puzzle. Here are a few 2026 program facts worth knowing as you plan:

• Part D (drug coverage) now has a $2,100 annual out-of-pocket cap in 2026.
• The Part D maximum deductible is $615 for 2026.
• The old "donut hole" coverage gap was eliminated in 2025; Part D now has three phases.
• The Medicare Prescription Payment Plan lets you spread drug costs across the year in monthly installments.
• IRMAA income-based premium surcharges kick in above $109,000 for single filers in 2026.
• Medicare Annual Enrollment runs Oct. 15 – Dec. 7, and Medicare Advantage Open Enrollment runs Jan. 1 – March 31.

Trenton sits in Mercer County, where — as in the rest of New Jersey — Medigap plan availability is regulated at the state and county level. If you want to see which insurers offer which lettered plans in your ZIP code, Medicare's online plan finder can pull that up.