Cal. Code Regs. tit. 22, § 50775
(a) Persons eligible for both Medicare Part A (Hospital) and Part B (Outpatient) benefits under the Social Security Act, Title XVIII, are persons or their spouses who have the required number of quarters of covered employment, are citizens of the United States or aliens legally present in the United States for at least five years, and who meet at least one of the following:
(b) Persons eligible for only Medicare Part B benefits are persons who are either citizens of the United States or are aliens legally present in the United States for at least five years, and are all of the following:
1. Amendment filed 12-15-77; effective thirtieth day thereafter (Register 77, No. 51).