Medicare Supplement

How Medicare Supplement letters work in Brookline, Mass.

BROOKLINE, Mass. — If you've ever tried to compare Medicare Supplement plans and felt like you were reading an eye chart — Plan A, Plan B, Plan G, Plan N — you're not alone. Those letters aren't random. They're part of a system designed to make shopping for extra Medicare coverage easier, not harder.

Here's what Medigap actually does, how the lettered plans work, and what Brookline residents should know before Medicare's Annual Enrollment Period wraps up on Dec. 7.

What Medigap is — and what it isn't

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 costs that Original Medicare leaves behind — things like coinsurance, copays, and certain deductibles.

Medigap is not the same thing as Medicare Advantage (Part C). You can't have both at the same time. Medigap sits next to Original Medicare; Medicare Advantage replaces the way you get your Part A and Part B benefits. Medigap also does not include prescription drug coverage — you'd need a separate Part D plan for that.

Why the plans have letters

In most states, Medigap plans are standardized by the federal government. That means Plan G sold by one company covers the same core benefits as Plan G sold by any other company. The letters — A, B, C, D, F, G, K, L, M, and N — refer to the benefit package, not the insurance carrier.

Massachusetts is one of three states (along with Minnesota and Wisconsin) that use their own standardized system rather than the federal letters. So a shopper in Brookline will see Medigap options structured a bit differently than a shopper in, say, Florida. The idea is still the same: consumer protection through standardization.

What the standardization actually means for you

Because benefits are locked in by law, the main things that vary between two companies selling the "same" plan are:

• Price. Premiums can differ significantly between carriers for identical coverage.
• Customer service and billing.
• How the price changes over time. Some policies use "attained-age," "issue-age," or "community" rating, which affects how premiums rise as you get older.

That's why comparing Medigap plans is really about comparing two things: which benefit package fits your needs, and which company offers a fair, stable price for it.

The enrollment window that matters most

The single most important thing to know about Medigap is that the best time to buy is during your Medigap Open Enrollment Period — a six-month window that starts 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.

Outside that window, in most cases, carriers can use medical underwriting. That means pre-existing conditions can affect whether you're accepted or what you pay. There are some limited guaranteed-issue rights that apply in specific situations, but the six-month window is your strongest protection.

How Medigap fits with the rest of Medicare in 2026

A few program-level facts worth keeping in mind as you weigh your options:

• Part D out-of-pocket cap: $2,100 for 2026. Once you hit that ceiling on covered drugs, you pay $0 for the rest of the year.
• Part D maximum deductible: $615.
• The coverage gap ("donut hole") is gone as of 2025. Part D now has three phases instead of four.
• Medicare Prescription Payment Plan: an optional program that lets you spread your drug costs across the calendar year in monthly payments.
• IRMAA surcharges begin above $109,000 in income for a single filer in 2026.

None of those figures are Medigap-specific, but they matter because Medigap works around them. If you pair Original Medicare with a Medigap policy, you'll also want to think about a Part D drug plan.

What Brookline residents can look at locally

Brookline is in Norfolk County, where Medicare beneficiaries can choose between staying with Original Medicare (often paired with a Medigap policy and a stand-alone Part D plan) or enrolling in a Medicare Advantage plan. Availability and the number of carriers offering coverage are set at the county level, not the town level, so a neighbor a few blocks over in Boston may see slightly different options.

The Annual Enrollment Period runs Oct. 15 through Dec. 7 each year. The Medicare Advantage Open Enrollment Period runs Jan. 1 through March 31. Medigap, importantly, has its own enrollment rules and isn't tied to those windows.