Medicare Supplement

Medigap, explained: what those letter plans really cover

LOS ANGELES — If you're on Original Medicare (Part A and Part B), you've probably noticed it doesn't pay for everything. There's a deductible before hospital coverage kicks in, and Part B generally covers 80% of approved outpatient costs, leaving you responsible for the other 20% — with no yearly limit on what you could owe.

Medigap in Los Angeles: filling the gaps in Original Medicare

That's the gap Medicare Supplement insurance, better known as Medigap, is designed to fill. Here in Los Angeles — part of Los Angeles County, the largest Medicare market in the country — Medigap is one of the two main paths people take alongside Original Medicare. (The other is Medicare Advantage, which works very differently.) This article walks through what Medigap does, how the standardized letter plans work, and where to get trustworthy help.

What Medigap actually does

Medigap is private insurance you buy on top of Original Medicare. It doesn't replace Medicare — it works with it. After Medicare pays its share of a covered service, your Medigap policy pays some or all of what's left, depending on which lettered plan you have.

In plain terms, Medigap can help cover things like:

• Part A hospital coinsurance and extra days after Medicare benefits are used up
• Part B coinsurance or copayments (the 20% share)
• The first three pints of blood
• Part A hospice coinsurance
• Skilled nursing facility coinsurance (on most plans)
• The Part A deductible (on most plans)

What Medigap does not cover: prescription drugs (you'd add a separate Part D plan), routine dental, vision, hearing aids, long-term custodial care, or private-duty nursing. It also doesn't work with Medicare Advantage — you have to be on Original Medicare to use it.

How the standardized letter plans work

Here's the part that trips people up. Medigap plans are sold by private insurance companies, but the benefits inside each lettered plan are standardized by the federal government. That means Plan G from one company covers the exact same medical benefits as Plan G from another company. The price and customer service can differ — the coverage cannot.

In most states, including California, Medigap plans are labeled with letters: A, B, C, D, F, G, K, L, M, and N. A few important notes from 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, those two plans aren't an option for you.
• Plan G has become the most comprehensive option for newer enrollees, though it doesn't pay the Part B deductible.
• Plans K and L have lower premiums but include yearly out-of-pocket limits and cost-sharing.
• Plan N has lower premiums than G but adds small copays for some office and ER visits.

Massachusetts, Minnesota, and Wisconsin standardize their Medigap plans differently, but California uses the letter system.

The best time to buy: your Medigap Open Enrollment Period

This is the piece a lot of Angelenos miss, and it matters.

Your Medigap Open Enrollment Period is a one-time, six-month window that starts the month you're 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, and they cannot turn you down or charge you more because of health problems.

Outside that window, in most cases, insurers in California can use medical underwriting — meaning they can review your health history and potentially deny coverage or charge more. California does offer a "birthday rule" that lets existing Medigap holders switch to an equal or lesser plan around their birthday each year without underwriting, but the rules are specific. Your local SHIP counselor can walk you through them.

Medigap vs. Medicare Advantage — a quick clarifier

People often ask which is "better." They're really two different systems:

• Original Medicare + Medigap (+ usually a Part D drug plan): You can see any doctor or hospital in the U.S. that accepts Medicare. Medigap handles most of your cost-sharing. You pay a monthly Medigap premium.
• Medicare Advantage (Part C): A private plan replaces how you get your Part A and Part B benefits, usually with a network and often with drug coverage bundled in. You cannot use a Medigap policy with it.

Los Angeles County has a large number of Medicare Advantage plans and carriers available, so both paths are on the table here. Which one fits depends on your doctors, your medications, your travel, and your budget — not on which one is "best" in the abstract.

Don't forget prescription drugs

Medigap doesn't cover prescriptions. If you go the Medigap route, you'll usually want to add a stand-alone Part D drug plan.

A few 2026 program figures worth knowing, straight from Medicare:

• Part D now has a $2,100 annual out-of-pocket cap on covered prescriptions.
• The Part D deductible maxes out at $615 (plans can charge less).
• The old "donut hole" coverage gap has been eliminated as of 2025 — Part D now has three phases instead of four.
• The Medicare Prescription Payment Plan lets you spread your drug costs across the year in monthly installments if that helps your budget.
• IRMAA surcharges on Part B and Part D premiums begin above $109,000 in income for a single filer in 2026.