As a licensed Medicare agent who works with California clients, one of the most common questions I hear is how to switch from Medicare Advantage to Medigap. The switch is very doable.
It also comes with a few rules that catch people off guard, such as getting the timing right. This guide walks you through why people make the change, when you are allowed to do it, and the exact steps to follow here in California.
A reminder: A Medigap policy works only with Original Medicare. To make the switch, you leave your Medicare Advantage plan and return to Original Medicare (Part A and Part B). Your Medigap policy then pays its share of the costs Original Medicare doesn’t cover.
Why Switch from Medicare Advantage to Medigap?
People make this move for a few reasons:
- Less paperwork: Medicare Advantage often require referrals and prior approval for care.
- More choice: Medigap works alongside Original Medicare, so you can see almost any doctor or hospital in the country that accepts Medicare.
- Predictable costs: After you pay your monthly premium and the small Part B deductible, a plan like Plan G covers most of what Original Medicare doesn’t.
Living in California adds its own reasons to switch to Medigap. In recent years, several California insurers have dropped hospital systems and physician groups from their Advantage networks. Patients who wanted to keep their own doctors have turned to Medigap for steadier access to care.
Birthday Rule Medigap Confusion
Many Californians have heard about the birthday rule, which causes confusion. The California birthday rule gives people who already have a Medigap plan the ability to switch to another Medigap plan with equal or lesser benefits. No health questions apply during that window.
The Birthday Rule is active during a 60-day window each year, starting on your birthday.
The birthday rule does not apply when you move from Medicare Advantage to Medigap. If Medicare Advantage is your current coverage, you will use one of the other paths in this guide.
When You Can Make the Switch
You can drop a Medicare Advantage plan and return to Original Medicare during set times of the year.
- The Medicare Advantage Open Enrollment Period: During this window (January 1 to March 31), you can leave your Advantage plan and go back to Original Medicare. Your new coverage starts the first day of the following month.
- Fall Open Enrollment: This runs from October 15 to December 7, and changes you make during this period take effect on January 1.
- Special Enrollment Periods: These open for certain life events, such as moving out of your plan’s service area or losing other coverage. These situations often come with extra protections, which the next sections explain.
Can You Be Turned Down for Medigap?
Getting back into Original Medicare — using one of the above methods — is easy. But based on your answers to a health questionnaire, a Medigap insurer can charge you a higher premium or deny your application for Medigap.
Outside of certain protected windows, California insurers can use medical underwriting for Medigap based on your health history, past treatments, and current medications.
However, a denial from one company does not mean every company will deny you. Each insurer sets its own standards. A licensed agent can help you find carriers whose rules fit your health picture — I have clients who I’ve helped successfully make the switch. But talk to someone before switching on your own.
Several situations let you buy a Medigap policy with no health questions at all. These are your best openings for a smooth switch.
California Guaranteed-Issue Situations
You gain a guaranteed-issue right when your Medicare Advantage plan changes in ways outside your control, such as your plan leaving the market, moving you into a different plan, or your plan ending its contract with your doctors. It can also include you moving out of the plan’s service area.
In these cases, you have a set window to buy certain Medigap plans with no health screening. California gives residents extra time, by adding a 60-day open enrollment period on top of the federal guaranteed right (63 days), for a total of 123 days.
For example, Californians whose Advantage plan ended on December 31, 2026 will have a guaranteed right to buy a Medigap policy through May 3, 2026.
The 12-Month Trial Right
You get this federal right in two cases:
- The first is when you joined a Medicare Advantage plan as soon as you became eligible for Medicare at 65.
- The second is when you dropped a Medigap policy to try Medicare Advantage for the first time.
In both cases, you can leave the Advantage plan within your first 12 months and buy a Medigap policy with guaranteed acceptance.
Step-by-Step: How to Make the Switch
Once you know your timing and your rights, the switch follows a clear order. Follow these steps in sequence to keep your coverage seamless.
- Choose your Medigap plan letter. Plans are standardized by letter, so a Plan G covers the same benefits no matter which company sells it. Plan G and Plan N are the most popular choices in California for 2026. Plans C and F are closed to anyone who became eligible for Medicare on or after January 1, 2020.
- Apply for Medigap and get approved first. If you do not have a trial right or guaranteed-issue right, apply for your Medigap policy before you touch your Advantage plan. Wait for the insurer’s approval. This step protects you from being left without supplemental coverage.
- Sign up for a Part D drug plan. Medigap does not include prescription drugs. Choose a standalone Medicare Part D plan and set its start date.
- Disenroll from your Advantage plan. Enroll in Original Medicare during one of the windows above. Signing up for a standalone Part D plan will also end your Advantage plan automatically in most cases. You can also call Medicare directly to disenroll.
- Confirm your start dates. Make sure your Medigap policy, your Part D plan, and your Original Medicare coverage all begin on the same date. Matching start dates keep you covered with no costly gaps.
What Medigap Costs in California in 2026
Your total monthly cost after switching has three main parts.
The Original Part B premium is $202.90 for most people in 2026. You pay this amount to Medicare on any type of Medicare coverage.
Your Medigap premium is a separate monthly cost. Your exact rate depends on your age, your ZIP code, your gender, tobacco use, and the insurer you choose. In California in 2026, Plan G commonly runs about $130 to $250 per month. Plan N usually costs less each month and comes with small copays for some visits.
Original Part D: Your drug plan will add a third monthly premium, which varies by plan.
Common Mistakes to Avoid
A few missteps come up again and again. Watch for these:
- Dropping your Advantage plan before Medigap is approved. Without a trial or guaranteed-issue right, a denial could leave you with no supplemental coverage and on the hook for 20% of all costs, from doctor’s visits to hospital stays.
- Assuming the birthday rule applies. It helps current Medigap members only, not people switching to Original Medicare + Medigap.
- Letting a guaranteed-issue window close. These windows have firm deadlines. Mark yours and apply early.
- Shopping with only one insurer. The same Plan G can cost hundreds of dollars more from one company than another, so compare several.
Getting Help in California
You do not have to figure this out alone. California offers strong free support.
HICAP, the Health Insurance Counseling and Advocacy Program, gives free, unbiased Medicare counseling to California residents. A HICAP counselor can walk you through your options and your rights with no sales pressure.
A licensed Medicare agent can also guide you. A good agent compares plans across many carriers, checks which insurers fit your health history, and lines up your start dates so nothing slips. As an agent, my goal is to make the switch smooth and to help you land in the coverage that fits your health and your budget.
Frequently Asked Questions
Can I switch from Medicare Advantage to Medigap any time of year?
You can leave a Medicare Advantage plan during set windows. The main ones are the Medicare Advantage Open Enrollment Period, from January 1 to March 31, and Fall Open Enrollment, from October 15 to December 7. There are also Special Enrollment Periods open for events like moving or losing coverage.
Will I have to answer health questions?
It depends on your situation. With a 12-month trial right or a guaranteed-issue right, you buy Medigap with no health questions. Outside those windows, California insurers can review your health and adjust your rate or deny your application.
Does the California birthday rule let me switch from Advantage to Medigap?
No. The birthday rule is only for people who already have a Medigap plan and want to move to another Medigap plan. It does not cover a switch from Medicare Advantage.
What happens to my drug coverage when I switch?
Your drug coverage from the Advantage plan ends. You need to enroll in a standalone Part D plan to stay covered. Do this within 63 days to avoid a permanent late penalty.
Can a pre-existing condition get me denied?
Inside a trial right or guaranteed-issue window, no. A pre-existing condition cannot block you. Outside those windows, a California insurer can consider your health history during underwriting. A denial from one carrier does not mean every carrier will say no.
This guide is for general educational purposes and reflects 2026 figures and California rules. Costs, plan availability, and state rules can change and vary by situation. Confirm current details at Medicare.gov, with your local HICAP office, or with a licensed California insurance agent before you make a decision.