Medicare Supplement

Does California's birthday rule change your Medigap options?

Fremont, Calif. — If you have Original Medicare and you live in Fremont, a Medigap policy is the piece that helps pay the deductibles, copays and coinsurance Medicare Parts A and B leave behind. The plans are federally standardized by letter, which means a Plan G is a Plan G no matter who sells it. What changes from one company to the next is the price and the customer service — not the benefits inside each letter.

Here is a plain-English guide to which Medigap letters people in Fremont can buy, how the policy works alongside Original Medicare and a Part D drug plan, and the California-specific rules that shape the choice.

What Medigap is (and what it is not)

Medigap is private insurance that pairs with Original Medicare. After Medicare pays its share of a covered service, your Medigap policy picks up some or all of what you would otherwise owe — things like the Part A hospital deductible, coinsurance days in the hospital, and the 20% Part B coinsurance for doctor visits.

Two things Medigap does not do:

• It does not cover prescription drugs. For that, you add a stand-alone Part D plan.
• It does not work with Medicare Advantage. You either have Original Medicare + Medigap (+ usually Part D), or you have a Medicare Advantage plan. Not both.

The plan letters you can buy in California

California follows the federal standardized Medigap chart. If you are newly eligible for Medicare today, the letters open to you are:

A, B, D, G, G-High Deductible, K, L, M and N.

Plans C and F are only available to people who became eligible for Medicare before January 1, 2020. That is a federal rule, not a California one.

Every letter covers the same benefits from company to company. A Plan N sold by one insurer covers exactly what a Plan N sold by another insurer covers. That is why shopping Medigap is mostly about comparing the price and stability of the company behind the same letter — not the benefits inside it.

The table below lists every insurer selling Medigap in California and the letters each one offers.

How Medigap pairs with Part D

Because Medigap ignores prescriptions, most Fremont residents on Original Medicare add a stand-alone Part D plan. A few 2026 numbers worth knowing:

• The Part D out-of-pocket cap is $2,100 in 2026. Once your covered drug spending hits that limit, you pay $0 for the rest of the year.
• The maximum Part D deductible is $615.
• The old "donut hole" coverage gap ended in 2025. Part D now has three simple phases.
• The Medicare Prescription Payment Plan lets you spread drug costs into monthly installments across the year if you want.

If your income (single filer, 2026) is above $109,000, IRMAA surcharges may raise your Part B and Part D premiums.

California rules that shape the choice

A few state-specific points to know as you shop:

• The California "birthday rule." California is one of a handful of states that lets Medigap policyholders switch policies once a year, during a window tied to their birthday, without medical underwriting — as long as they move to a plan of equal or lesser benefits. The exact length of the window and the details can change, so confirm current rules with the California Department of Insurance or your local SHIP counselor before you act.
• Federal guaranteed-issue rights. In your six-month Medigap Open Enrollment Period, which starts the month you are 65 or older and enrolled in Part B, insurers must sell you any Medigap plan they offer without asking about your health. Outside that window, and outside California's birthday rule, they generally can use medical underwriting.
• Pricing methods. California insurers can price Medigap policies in different ways (for example, by age when you enroll, or by current age). Two policies with the same letter can have very different price tags today and different price paths over time. Ask each insurer how the policy is priced before you sign.

Insurers selling Medigap in California

The insurers currently selling Medigap in California include AARP - UnitedHealthcare Insurance Company, AFLAC, American Retirement Life Insurance Company (CIGNA), Anthem BlueCross - California, Bankers Life (Underwritten by Washington National Insurance Company), Blue Shield of California Life & Health Insurance Company, Continental Life Insurance Company of Brentwood, Tennessee (Aetna), Everence Association Inc., Humana (Humana Insurance Company), Insurance Company of North America, Lumos Insurance, Mutual of Omaha (United World Life Insurance Company), State Farm Mutual Automobile Insurance Company, United American Insurance Company and USAA Life Insurance Company.

Not every insurer sells every letter. The table below shows which letters each company offers, so you can see at a glance who competes on the plan you are considering.

When to enroll

Your best window to buy Medigap is your six-month Medigap Open Enrollment Period, which starts the first month you are both 65 or older and enrolled in Part B. During that window, you have guaranteed-issue rights for any Medigap plan any California insurer sells.

Medigap itself does not use Medicare's Annual Enrollment Period (Oct. 15 – Dec. 7) or the Medicare Advantage Open Enrollment Period (Jan. 1 – March 31) — those windows are for Part D and Medicare Advantage. But if you plan to leave Medicare Advantage and return to Original Medicare + Medigap, those dates matter for the Medicare Advantage side of the move.