Medicare Supplement

Does California's birthday rule let you switch Medigap?

Medigap — also called Medicare Supplement Insurance — is a policy you buy from a private insurance company to help pay some of the costs Original Medicare leaves behind. Things like coinsurance, copayments and, for some letters, the Part A deductible.

Medicare SupplementSanta Clarita, CA

What Medigap is, and how it fits with Original Medicare

Medigap only works alongside Original Medicare (Part A hospital and Part B medical). It does not work with Medicare Advantage. And it does not include prescription drug coverage, so most people in Santa Clarita who go the Original Medicare + Medigap route also sign up for a stand-alone Part D drug plan.

Santa Clarita is in Los Angeles County. Medigap rules, though, are set by the federal government and by California — not by the county — so the plan letters and consumer protections are the same across the state.

The plan letters you can buy in California today

The federal government standardizes Medigap into lettered plans. That means a Plan G from one insurer covers the same core benefits as a Plan G from any other insurer in California. What can differ is the premium, the customer service and whether the insurer uses medical underwriting when you apply outside a guaranteed-issue window.

If you are newly eligible for Medicare today, these are the letters available in California:

• Plans A, B, D, G, G high-deductible, K, L, M and N.
• Plans C and F are closed to people who became eligible for Medicare on or after January 1, 2020. If you were eligible before that date and never enrolled, you may still be able to buy them.

Massachusetts, Minnesota and Wisconsin use their own Medigap systems — California does not, so the federal letters apply here.

Which insurers sell Medigap in Santa Clarita

California has a long list of insurers licensed to sell Medigap policies. Not every insurer offers every letter, so it helps to start with the letter you want and then look at who sells it.

The table below lists every insurer and the plans each one offers in California. You will see familiar names like AARP - UnitedHealthcare Insurance Company, Anthem BlueCross - California, Blue Shield of California Life & Health Insurance Company, Humana, Mutual of Omaha and State Farm Mutual Automobile Insurance Company, alongside carriers such as AFLAC, American Retirement Life Insurance Company (CIGNA), Bankers Life, Continental Life Insurance Company of Brentwood, Tennessee (Aetna), Everence Association Inc., Insurance Company of North America, Lumos Insurance, United American Insurance Company and USAA Life Insurance Company.

Because the benefits inside each letter are set by federal rules, the shopping question is not "whose Plan G is better?" It is "which insurer will price and service my Plan G in a way that works for me over time?"

Pairing Medigap with Part D in 2026

Medigap does not cover prescription drugs, so if you want drug coverage you enroll in a stand-alone Part D plan. A few 2026 program-level facts worth knowing:

• The Part D maximum deductible is $615.
• There is a $2,100 out-of-pocket cap on covered Part D drugs.
• The old coverage gap ("donut hole") is gone as of 2025 — Part D now has three phases.
• The Medicare Prescription Payment Plan lets you spread your drug costs across the year in monthly payments if you choose.
• IRMAA surcharges — extra amounts added to Part B and Part D premiums — begin above $109,000 in income for a single filer in 2026.

You can compare Part D plans available in your ZIP code at medicare.gov during the Annual Enrollment Period, October 15 – December 7.

California rules that shape your Medigap choice

Federal law gives you a one-time, six-month Medigap Open Enrollment Period that starts the month your Part B begins and you are 65 or older. During that window, an insurer must sell you any Medigap policy it offers, at the same price it charges healthy people, and cannot make you wait for coverage of a pre-existing condition beyond limited federal rules.

California adds a well-known protection called the "birthday rule." In short, each year around your birthday, current Medigap policyholders get a window to switch to another Medigap plan with equal or lesser benefits without going through medical underwriting. The exact length of the window and the rules for how it works are set by the state, so confirm the current details with the California Department of Insurance before you apply.

California also has specific protections for people under 65 who qualify for Medicare due to disability, and additional guaranteed-issue situations beyond federal law. Your local State Health Insurance Assistance Program (SHIP) — called HICAP in California — can walk you through which protections apply to your situation.

How to shop without getting overwhelmed

A simple order of operations helps:

1. Decide which lettered plan matches how you use care. Plan G and Plan N are the most common choices for newly eligible people; K, L and high-deductible G trade lower premiums for more cost-sharing. 2. Once you have picked a letter, compare the insurers that sell that letter in California. Ask about the premium today, how the insurer has raised premiums in the past, and how they set rates (age-based methods differ). 3. If you are switching, ask whether you qualify for guaranteed issue — through the California birthday rule or another protection — before you apply, so you do not face underwriting by surprise. 4. Sign up for a separate Part D plan during your Initial Enrollment Period or the Annual Enrollment Period.