In California, you can buy any Medigap policy without health questions during your 6-month Medigap Open Enrollment Period, which starts the first month you have Part B and are 65 or older. After that, California's birthday rule gives anyone who already has Medigap a 60-day window each year, starting on their birthday, to switch to another Medigap policy with the same or fewer benefits without medical underwriting.
What Medigap does
Original Medicare pays a large share of your medical costs, but not all of it. You still have deductibles, coinsurance, and copayments, and Original Medicare has no yearly cap on what you can owe. A Medicare Supplement policy, sold by a private insurance company, helps pay some or all of those leftover costs.
Medigap plans are standardized and named by letter, such as Plan G or Plan N. The letter tells you the benefits. The company and the price are what you shop. Medigap only works with Original Medicare. It does not include drug coverage, so most people pair it with a separate Part D plan.
Your first window: 6-month Medigap Open Enrollment
Your Medigap Open Enrollment Period starts the first month you have Medicare Part B and are 65 or older, and it lasts 6 months. During this window:
- A company cannot refuse to sell you any Medigap policy it offers.
- It cannot charge you more because of your health.
- It cannot make you wait for coverage of a pre-existing condition, as long as you had enough prior creditable coverage.
If you delayed Part B because you were still working, this window starts when your Part B starts, not when you turned 65.
California's birthday rule
This is the rule most people in California have never heard of. If you already have a Medigap policy, you get a 60-day window every year that begins on your birthday. During those 60 days, you can switch to another Medigap policy with the same or fewer benefits, and the new company cannot use your health to decline you.
Why it matters: Medigap premiums can rise over time. The birthday rule lets you shop the same coverage again every year without worrying about health questions.
Example: Your birthday is March 10 and you have a Plan G. From March 10 through early May, you can move to a Plan G, or a plan with fewer benefits, from another company without medical underwriting. Start your comparison a few weeks before your birthday so you are ready when the window opens.
A few cautions. Keep your current policy until the new one is approved and in force, so you never have a gap. And make sure you are comparing the same plan letter, so you know you are not giving up benefits by accident.
Other times you are protected
Federal and California law give you a guaranteed right to buy certain Medigap policies in specific situations, including:
- Trial right. You joined a Medicare Advantage plan when you were first eligible at 65, or you dropped a Medigap policy to try Advantage for the first time, and you want to return to Original Medicare within the first 12 months.
- Your plan leaves. Your Medicare Advantage plan stops serving your area, or you move out of its service area.
- Your coverage ends. Employer or union coverage that paid after Medicare ends.
- Your company fails. Your Medigap company goes bankrupt, or misled you or broke the rules.
- Losing Medi-Cal. California also protects people who lose Medi-Cal eligibility, within a set window.
Each situation has its own deadline, often 60 or 63 days, and its own list of policies you can choose from. Keep the letter that tells you your coverage is ending. It is your proof.
Your 30-day free look
When you buy a new Medigap policy, you get time to review it. If you decide it is not right, you can return it during the free look period for a refund of premium paid. If you are replacing an existing policy, do not cancel the old one until the free look on the new one has passed and you are sure.
How to compare Medigap policies
- Pick the letter first. Decide which level of coverage you want.
- Compare price for that letter. Same benefits, different companies, different premiums.
- Ask how the price changes. Companies price by your current age, your age when you bought, or the same for everyone. That affects what you pay later.
- Look at the company. Service and stability matter over the years you will own the policy.
- Use your birthday window every year. Recheck the market for the same coverage.
I can compare the Medigap policies I am appointed to offer side by side with you. For a list of every company selling Medigap in California, the California Department of Insurance publishes one, and HICAP at 1-800-434-0222 offers free, unbiased counseling.
Common questions
What is the California birthday rule for Medigap?
If you already have a Medigap policy in California, you get a 60-day window every year beginning on your birthday. During that window you can switch to another Medigap policy with the same or fewer benefits, and the company cannot use your health to turn you down.
Can I use the birthday rule to switch from Medicare Advantage to Medigap?
No. The birthday rule applies to people who already have a Medigap policy and want to change to a different one with equal or lesser benefits. Moving from Medicare Advantage to Medigap follows different rules, and outside protected situations, health questions can apply.
Is there an annual open enrollment for Medigap in California?
Not for everyone. A 2025 bill, SB 242, would have created a yearly 90-day guaranteed issue window starting in 2027, but it did not pass. The birthday rule and the protected situations on this page are the rules that apply today.
Can I get Medigap in California if I am under 65 and on Medicare because of a disability?
California provides an open enrollment period for people under 65 who have Medicare because of a disability. People under 65 who qualify because of end-stage renal disease have more limited access. The details depend on your situation, so it is worth a careful review.
Are Medigap plans the same from every company?
The benefits are standardized by letter. A Plan G from one company covers the same basic benefits as a Plan G from another. The premium, how the company prices it over time, and the company's service can differ.
Where these facts come from: California Insurance Code 10192.91 and Health and Safety Code 1358.11 as summarized by the California Health Benefits Review Program, April 2025; Medicare.gov: Medigap basics, guaranteed issue rights, and the Medigap free look period. Rules and dollar amounts change. Page reviewed October 4, 2026.