Medicare Supplement

Plan A to Plan N: How Medigap's Letters Actually Line Up

VACAVILLE, Calif. — If you have Original Medicare and you keep seeing letters like Plan A, Plan G, or Plan N in the mail, you are not alone. Those letters are not random branding. They are a nationwide system for Medicare Supplement insurance — often called Medigap — and understanding how the system works can make the shopping process a lot less confusing.

Here in Vacaville, which sits in Solano County, retirees have the same Medigap letter choices that people in most other states have. That is because Medigap plans are standardized by federal rule, even though they are sold by private insurance companies.

What Medigap actually does

Original Medicare pays most of your hospital and doctor bills, but not all of them. You are still on the hook for things like the Part A hospital deductible, Part B coinsurance (usually 20% of the approved amount), and other cost-sharing pieces.

A Medigap policy is private insurance that fills in some or all of those gaps. Depending on the letter you choose, it may pick up the Part A deductible, Part B coinsurance, hospital costs after Medicare's benefits run out, and more. Medigap does not add drug coverage — for prescriptions, you would enroll in a separate Part D plan.

Why the letters exist

Before the letters were standardized, Medigap shopping was chaotic. Every company designed its own benefits, and it was almost impossible to compare policies fairly.

Congress fixed that by requiring insurers to sell only from a set list of standardized plans, each identified by a letter. Today, Plan G from one company covers the same federally required benefits as Plan G from another company. What can differ is the price, the customer service, and sometimes extras like discounts on gym memberships.

That is why two neighbors on the same street in Vacaville can hold "Plan G" policies from different carriers and get the exact same core coverage.

A quick tour of the letters

There are ten standardized Medigap plans available in most states: A, B, C, D, F, G, K, L, M, and N. A few notes worth knowing, per Medicare.gov:

• Plans C and F are only available to people who became eligible for Medicare before January 1, 2020. If you turned 65 after that date, you cannot buy them as a new customer.
• Plans K and L have lower premiums but come with out-of-pocket limits and higher cost-sharing until you hit those limits.
• Plan N generally has lower premiums than Plan G but asks you to pay small copays for some office and emergency room visits.
• Massachusetts, Minnesota, and Wisconsin use their own standardized systems that look different from the letter plans.

The letters do not rank quality. Plan A is not "worse" than Plan N — they simply cover different combinations of gaps.

How Medigap fits with the rest of Medicare

Medigap is designed to sit on top of Original Medicare (Part A and Part B). You cannot pair a Medigap policy with a Medicare Advantage plan; the two are different paths.

If you have Original Medicare plus a Medigap policy plus a stand-alone Part D drug plan, you have essentially built a three-part package. Part D is worth understanding on its own: for 2026, the Part D out-of-pocket cap is $2,100, the maximum Part D deductible is $615, and the old coverage gap or "donut hole" has been eliminated as of 2025. Medicare also offers the Medicare Prescription Payment Plan, an optional way to spread drug costs across the year.

Higher-income beneficiaries may also pay IRMAA surcharges on Part B and Part D; those begin above $109,000 in income for a single filer in 2026.

Timing matters more than most people realize

The single most important thing to know about Medigap is timing. Your Medigap Open Enrollment Period is a one-time, six-month window that starts the month you are 65 or older AND enrolled in Part B. During that window, insurers cannot turn you down or charge you more because of your health.

Outside that window, in most states, insurers can use medical underwriting. That means a health condition could affect whether you can switch plans or what you pay. California has some additional consumer protections, including a "birthday rule" that lets Medigap enrollees change to certain plans each year around their birthday without new underwriting. A local SHIP counselor can walk you through how that works for your situation.

Where to get help in Solano County

Medigap decisions are personal. The same letter plan can be the right fit for one Vacaville retiree and the wrong fit for their neighbor, depending on health, budget, and travel habits.

For unbiased help, you can:

• Visit medicare.gov to compare Medigap policies available in your ZIP code.
• Call 1-800-MEDICARE (1-800-633-4227), available 24/7.
• Contact California's SHIP program, known as HICAP (Health Insurance Counseling and Advocacy Program), for free one-on-one counseling.