What the rule is
Under California law, a person who already has a Medigap policy has an annual open enrollment period lasting 60 days or more, commencing with their birthday. During that window they may purchase a Medigap policy with benefits equal to or lesser than their current standardized package, without health screening. Sixty days is the legal floor; some notices describe a longer company window. Read the notice your carrier sends.
Equal or lesser — not an upgrade
The usual use is the same letter with a different company (for example Plan G to Plan G) or a move to a letter with fewer standardized benefits (for example Plan G to Plan N). The birthday rule does not let you move up to a more comprehensive letter. Extra “innovative” benefits on a policy are generally not counted when comparing letters.
Who it does not cover
The birthday rule is for people who already have Medigap in California. It is not a guaranteed-issue path from Medicare Advantage into Medigap. Advantage members who want a Supplement follow different federal and state rules, which often include underwriting unless another guaranteed-issue right applies.
What to confirm before you apply
Write down your current letter, the start of your birthday window, and that the replacement has equal or lesser standardized benefits. Premiums vary by company and can change. Confirm details with the California Department of Insurance, your outline of coverage, and Medicare.gov. This website does not enroll you.
Related topics
2026 figures
California Medigap Birthday Rule
Find the 60-day window that starts on your birthday if you already have Medigap.
Educational answers — not a plan recommendation.
Educational estimate using public 2026 CMS figures. Not a bill, not a determination, and not a plan recommendation. Confirm on Medicare.gov or with Social Security. We are not affiliated with or endorsed by the U.S. Government or the federal Medicare program.
We are not affiliated with or endorsed by the U.S. Government or the federal Medicare program. This page is general education. We do not offer every plan available in your area. Currently we represent 6 organizations which offer Medicare Advantage and Part D products in California. The number of products available to you depends on your ZIP code. For a complete list of options, visit Medicare.gov, call 1-800-MEDICARE (1-800-633-4227), TTY 711, or California HICAP at 1-800-434-0222.