Cal. Welf. and Inst. Code § 4465
The Director of Developmental Services may deposit any funds of patients in the possession of each hospital administrator of a state hospital in trust with the treasurer pursuant to Section 16305.3, Government Code, or, subject to the approval of the Department of Finance, may deposit such funds in interest-bearing bank accounts or invest and reinvest such funds in any of the securities which are described in Article 1 (commencing with Section 16430), Chapter 3, Part 2, Division 1, Title 2 of the Government Code and for the purposes of deposit or investment only may mingle the funds of any patient with the funds of other patients. The hospital administrator with the consent of the patient may deposit the interest or increment on the funds of a patient in the state hospital in a special fund for each state hospital, to be designated the "benefit fund," of which he shall be the trustee. He may, with the approval of the Director of Developmental Services, expend the moneys in any such fund for the education or entertainment of the patients of the institution.
On and after December 1, 1970, the funds of a patient in a state hospital or a patient on leave of absence from a state hospital shall not be deposited in interest-bearing bank accounts or invested and reinvested pursuant to this section except when authorized by the patient; any interest or increment accruing on the funds of a patient on leave of absence from a state hospital shall be deposited in his account; any interest or increment accruing on the funds of a patient in a state hospital shall be deposited in his account, unless such patient authorizes their deposit in the state hospital's "benefit fund."
Any state hospital charges for patient care against the funds of a patient in the possession of a hospital administrator or deposited pursuant to this section and which are used to pay for such care, shall be stated in an itemized bill to the patient.
Ca. Welf. and Inst. Code § 4465