California Revenue And Taxation Code Section 19274

The local child support agency may refer to the Franchise Tax Board cases in which the social security number of the noncustodial parent is unknown. The Franchise Tax Board shall search its records to obtain the noncustodial parent`s social security number and furnish this information to the local child support agency to assist in the establishment or enforcement of a child support order. For purposes of administering this section, the Franchise Tax Board may use any services or information available for tax enforcement purposes, or available to a local child support agency or the Title IV-D agency in collecting or enforcing child support, or in locating absent or noncustodial parents.