Your situation · Turning 65
Turning 65 in California: what to do, and when
Seven months to enroll, one six-month window to buy any Medigap policy without health questions, a Kaiser decision most Californians have to make, and a few deadlines that carry a lifelong penalty. Here is the order to do things in.
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Your enrollment timeline
Enroll in Parts A and B through Social Security (ssa.gov or 1-800-772-1213) unless you are already receiving Social Security, in which case your card arrives automatically. Decide the Kaiser question: staying in Kaiser means Senior Advantage; leaving means Original Medicare with Medigap, or a non-Kaiser Advantage plan.
Part B starts on the first of the month. Your six-month Medigap open enrollment begins now. Your Advantage or Part D election can take effect the same day.
The Initial Enrollment Period closes. Enrolling in Part B in these last months delays your start date. Missing it entirely, without creditable employer coverage, adds a permanent 10%-per-year penalty.
The Part D clock: go 63 or more days without creditable coverage and a permanent penalty begins to accrue.
California’s Medigap birthday rule: switch your supplement to any carrier’s plan of equal or lesser benefits with no health questions. Mark it on the calendar; we do.
Still working at 65?
If you or your spouse are actively working and the employer has 20 or more employees, that group plan pays first and you can delay Part B without penalty, then use an eight-month Special Enrollment Period when the job or coverage ends. Employer plans with fewer than 20 employees generally pay secondary to Medicare, so you usually need Part B at 65. Note that COBRA and retiree coverage do not count as active employment. HSA contributions must stop before Part A begins (Part A is retroactive up to six months when you enroll later, which trips up a lot of people).
CalPERS retirees: a different menu
If your retiree health coverage comes through CalPERS, the rules are set by CalPERS: you must enroll in Medicare Parts A and B when eligible and then transfer into a CalPERS Medicare health plan (Kaiser Senior Advantage, the UnitedHealthcare and Anthem/Blue Shield Medicare plans, PERS Platinum and others, depending on the year). Many State and CSU retirees are reimbursed for part or all of their Part B premium. The individual-market plans on this site are separate from that menu. We can still explain Medicare itself, Part B timing and IRMAA plainly, and help you understand how the CalPERS options compare.
The three decisions
- Kaiser or not. This comes first in California, because it closes or opens every other door. Our Kaiser page lays it out honestly.
- Original Medicare plus Medigap and Part D, or Medicare Advantage. Freedom to use any doctor in the country versus a medical group with lower upfront costs and extras. Medigap and Advantage pages explain each.
- Which company and plan. Compared at your ZIP code against your doctors, their medical group, and your prescriptions.
The one thing not to do: assume you can buy Medigap later. Outside your six-month open enrollment, a guaranteed-issue event, or the birthday rule (which covers switching, not a first purchase), California insurers can ask health questions. If you might ever want a supplement, the cheapest time to buy one is at 65.
Good to know
Frequently asked questions
When should I sign up for Medicare if I’m turning 65 in California?
Enroll during the three months before your birthday month so coverage starts the month you turn 65. Your Initial Enrollment Period lasts seven months in total.
Does California have a Medigap birthday rule for people turning 65?
The birthday rule is for people who already have a Medigap policy and want to switch. At 65, your six-month open enrollment is broader: any plan, any carrier, no health questions. Buy in that window; use the birthday rule to re-shop in later years.
I am retiring through CalPERS. What is different?
CalPERS requires you to enroll in Medicare Parts A and B when eligible and move into a CalPERS Medicare plan to keep your CalPERS coverage; many State and CSU retirees get Part B reimbursed. Those plans are separate from the individual-market plans on this site.
What happens if I miss my Medicare enrollment deadline?
Without creditable employer coverage, you wait for the General Enrollment Period (Jan 1–Mar 31) and pay a permanent Part B penalty of 10% for each full year you delayed. Part D has its own permanent penalty after 63 days without creditable coverage.
Ready when you are
Turning 65 soon? Let’s map your timeline together.
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Sources we used on this page
- Medicare.gov: Medigap (Medicare Supplement Insurance)
- California Insurance Code §10192.11: Medicare supplement open enrollment and the birthday rule
- California Health Advocates: Medigap open enrollment, the birthday rule and guaranteed issue
- CalPERS: Medicare requirements for retirees and CalPERS Medicare health plans
- California Department of Aging: HICAP Medicare counseling (1-800-434-0222)
Figures are checked against the source at the review date in the byline below. If a source has changed since, the source wins.
Written and reviewed by Darin Weidauer — licensed insurance agent (NPN 18580338, CA License #0M00978), Gerontologist (USC Leonard Davis School of Gerontology), MBA, Registered Social Security Analyst, and 22-year U.S. Air Force veteran.Last reviewed September 4, 2026. Plan availability, benefits and costs change every plan year — verify current details at Medicare.gov, 1-800-MEDICARE, or California HICAP at 1-800-434-0222.