California Code, Code of Civil Procedure - CCP § 695.211

(a) Every money judgment or order for child support shall provide notice that interest on arrearages accrues at the legal rate.

(b) The notice provisions required by this section shall be incorporated in the appropriate Judicial Council forms.

(c) Upon implementation of the California Child Support Automation System prescribed in Chapter 4 (commencing with Section 10080) of Part 1 of Division 9 of the Welfare and Institutions Code and certification of the California Child Support Automation System by the United States Department of Health and Human Services, whenever a statement of account is issued by the local child support agency in any child support action, the statement shall include a statement of an amount of current support, arrears, and interest due.