Yes — you can move from a Medicare Advantage plan to a Medicare Supplement (Medigap) plan in California, but two things have to line up: you need a valid enrollment period to leave your Medicare Advantage plan, and you need a way to get accepted into a Medigap policy. For some people that second step is automatic. For others, it means answering health questions. This guide walks through exactly how the switch works in California, when you can make it, and where the state's rules help you.

QUICK ANSWER: To switch, you first leave your Medicare Advantage plan and return to Original Medicare (Part A and Part B), then apply for a Medigap policy. You can leave Medicare Advantage during the Annual Enrollment Period (October 15 – December 7), during the Medicare Advantage Open Enrollment Period (January 1 – March 31), or during a Special Enrollment Period if you qualify. Getting into a Medigap plan is the part that depends on your situation: if you have a guaranteed-issue right or a trial right, the insurer cannot turn you down or charge you more for health reasons. Outside of those protections, Medigap in California is medically underwritten, meaning the insurer can review your health history before approving you.

Step one: leaving Medicare Advantage

A Medigap policy only works alongside Original Medicare, not alongside a Medicare Advantage plan. So the first move is always to disenroll from Medicare Advantage and go back to Original Medicare. You can do that during one of these windows:

Leaving Medicare Advantage is the straightforward part. Getting approved for Medigap is where timing and rights matter most.

Step two: getting into a Medigap plan

Here's the piece many people don't hear until it's too late. Simply dropping Medicare Advantage during AEP or MA-OEP does not guarantee you a Medigap policy. Unless you have a guaranteed-issue right or a trial right, a California Medigap insurer can ask health questions and decide whether to accept you and at what price. If you have significant health conditions, you could be declined. That's why the smart order of operations is to apply for Medigap first, get approved, and only then drop your Medicare Advantage plan — so you're never left without a plan lined up.

There are two main paths to skip the health questions entirely.

Trial rights (a 12-month "test drive")

Medicare gives you a trial right in two situations:

  1. You joined Medicare Advantage when you first became eligible for Medicare at 65. If you decide within the first 12 months that Medicare Advantage isn't for you, you can switch to any Medigap policy sold in California with guaranteed issue — no health questions.
  2. You dropped a Medigap policy to try Medicare Advantage for the first time. If you leave that Medicare Advantage plan within 12 months, you can go back to your previous Medigap policy if it's still sold, or buy another one with guaranteed issue.

Trial rights are time-sensitive. The clock starts when your Medicare Advantage coverage begins, and you generally must apply for Medigap starting as early as 60 days before your Medicare Advantage coverage ends and no later than 63 days after it ends.

Guaranteed-issue rights

Separate from trial rights, you have guaranteed-issue protection in certain situations — for instance, if your Medicare Advantage plan leaves your area, stops being offered, or you move out of its service area. In those cases you can buy specific Medigap plans without medical underwriting, again within a 63-day window.

If you received a notice that your plan is not renewing for next year, that is exactly this situation — see our guide to what to do when your Medicare Advantage plan is discontinued in California for the deadlines and the step-by-step.

California law also goes beyond the federal rules in one way that matters every fall, covered in the next section.

If your Medicare Advantage plan is cutting benefits or raising costs

Under California Insurance Code § 10192.12, you may have a guaranteed-issue right to a Medigap policy if the Medicare Advantage plan you are enrolled in does any of these:

Your plan’s Annual Notice of Change, which arrives each fall, is where benefit and cost changes for the coming year are listed. Read it with this in mind.

Two limits matter:

  1. The same company comes first. The right is to a Medigap policy from the same insurer that offers your Medicare Advantage plan, or from a company tied to it. The law describes that as a subsidiary of the insurer’s parent company, or a network that contracts with the parent company.
  2. Other companies only in certain cases. If no Medigap policy is available to you from that insurer or those related companies, the law extends the right to a policy from any insurer when your plan raises its premium by 15 percent or more, raises physician, hospital or drug copayments by 15 percent or more, reduces any benefits, or ends its contract with a provider who is currently treating you for a reason other than quality of care. Enrolling with an unrelated insurer is allowed only during Medicare’s Annual Enrollment Period (October 15 – December 7), unless the reason is that your plan ended its relationship with a provider who is currently treating you. Even then, you can leave your Medicare Advantage plan only when Medicare allows it.

Timing: if you leave your plan for one of these reasons, the guaranteed-issue period starts 60 days before the date your disenrollment takes effect and ends 63 days after it. If you are applying to an unrelated insurer, the Annual Enrollment Period limit above still applies, so ask that insurer for its exact deadline.

The law covers only certain standardized Medigap plans, and which ones are open to you can depend on when you became eligible for Medicare. You will need to submit evidence of your disenrollment date with the application.

Before you rely on this right, confirm it with the Medigap insurer, and check with HICAP at 1-800-434-0222 or the California Department of Insurance at 1-800-927-4357. A parallel rule in Health and Safety Code § 1358.12 applies to Medigap coverage sold by health plans regulated by the Department of Managed Health Care; its Help Center is 1-888-466-2219. Get approved for the Medigap policy before you drop your Medicare Advantage plan.

Where the California Birthday Rule fits in

California is one of the few states with a "Birthday Rule" for Medigap — but it's often misunderstood in this context. The California Birthday Rule lets people who already have a Medigap policy switch to another Medigap plan of equal or lesser benefits each year, without underwriting, during a window that starts on their birthday.

The key point: the Birthday Rule does not help you get into Medigap when you're coming from Medicare Advantage. It only applies once you already hold a Medigap policy. So if you're leaving Medicare Advantage, you'll rely on a trial right or guaranteed-issue right to get accepted first — and then, in future years, the Birthday Rule can help you shop for a better rate. For a fuller picture of every switching window, see when you can change your Medigap plan in California.

Is switching the right move for you?

Medicare Advantage and Medigap are built differently, and one isn't universally better than the other. Medicare Advantage often has lower monthly premiums, provider networks, and extra benefits like dental or vision. Medigap usually costs more per month but offers broad provider access and more predictable out-of-pocket costs. Which fits depends on your health, your doctors, your budget, and how you like to handle surprises. Our side-by-side Medicare Advantage vs. Medicare Supplement comparison can help you think it through, and if you're newer to all of this, the turning 65 guide covers the basics.

Frequently asked questions

Can I switch from Medicare Advantage to Medigap any time I want?
No. You can leave Medicare Advantage during the Annual Enrollment Period (October 15 – December 7), the Medicare Advantage Open Enrollment Period (January 1 – March 31), or a qualifying Special Enrollment Period. Being accepted into a Medigap plan depends separately on whether you have a guaranteed-issue right, a trial right, or must go through medical underwriting.
My Medicare Advantage plan is cutting benefits or raising costs next year. Can I get a Medigap plan without health questions?
Possibly. California Insurance Code § 10192.12 gives a guaranteed-issue right when a Medicare Advantage plan reduces benefits, raises its premium or cost sharing, or ends its contract with a provider who is currently treating you for a reason other than quality of care. The right is first to a Medigap policy from the same insurer or a related company. It extends to other insurers only in certain cases, and for most of those only during the Annual Enrollment Period, October 15 to December 7. Confirm with the Medigap insurer, HICAP (1-800-434-0222) or the California Department of Insurance before you drop your current plan.
Will I have to answer health questions to get a Medigap plan?
Sometimes. If you have a trial right or a guaranteed-issue right, no — the insurer must accept you. Outside of those protections, Medigap in California is medically underwritten, so the insurer can review your health history before deciding.
Should I drop Medicare Advantage before or after applying for Medigap?
Generally apply for Medigap first and get approved before dropping Medicare Advantage, so you're not left without a plan in place. A licensed broker can help you sequence the timing correctly.
Does the California Birthday Rule let me switch from Medicare Advantage to Medigap?
No. The Birthday Rule only applies to people who already have a Medigap policy. It's useful for shopping for a better Medigap rate later, not for entering Medigap from Medicare Advantage.
Do I need a Part D drug plan if I switch?
Usually yes. Original Medicare with a Medigap policy does not include prescription drug coverage, so most people add a standalone Part D plan to avoid gaps and a potential late enrollment penalty.

Talk it through with someone local

Switching from Medicare Advantage to Medigap in California is very doable, but the order and timing matter, and the underwriting question is different for everyone. If you'd like help figuring out whether you qualify for a trial right or guaranteed issue — and whether the switch even makes sense for your situation — reach out for a free, no-obligation review. Consultations are always free, and there's no pressure to enroll in anything.

Sources & official references

Matt Medicares Insurance is an independent insurance brokerage and is not affiliated with or endorsed by Medicare, the Centers for Medicare & Medicaid Services, or any government agency. We do not offer every plan available in your area. Please contact Medicare.gov, 1-800-MEDICARE, or your local State Health Insurance Assistance Program (SHIP) to get information on all of your options. Last reviewed: October 2026. Medicare rules and figures reflect 2026 and can change — confirm current details at Medicare.gov.