What is the rule
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 is not covered
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.
See whether your birthday window is open
The Birthday Rule worksheet uses the birthday you enter and shows the 60-day window. It does not know your letter, your company, or whether you already have Medigap. If you do not already have a Supplement, this window does not apply. Compare letters on the Medicare Supplement list only after you know you are in the window. Confirm the notice from your company.
My Medicare Checkup
Answer a few questions about your ZIP code, what matters about cost and doctors, and where you get care. The summary shows the questions those answers raise. Confirm each one with the office, the plan, or Medicare.gov. A listing in a directory, or the name of a plan, does not show whether a doctor is in the network, whether a prescription is covered, or what you would pay this year.
Start My Medicare CheckupYou will get a summary of the questions to verify. You can also talk it through with Alan.
2026 figures
California Medigap Birthday Rule
Find the 60-day window that starts on your birthday if you already have Medigap.