Cal. Education Code § 46609

The governing board of a unified school district, whose boundaries are coterminous with the boundaries of a county, and which is contiguous to an adjoining state, may provide for the education of all or any number of the high school pupils of the district who reside in the district by the attendance of these pupils at the schools of a school district of an adjoining state. The governing board of the unified school district may enter an agreement with the school district of an adjoining state for the education of these pupils, subject to the terms and conditions agreed upon. The provisions of Sections 2000 to 2011, inclusive, do not apply to pupils educated pursuant to an agreement authorized by this section. The average daily attendance of pupils educated pursuant to an agreement authorized by this section shall be credited to the district of residence for apportionment purposes. The superintendent of schools of the district, or the principal of the school, in the adjoining state attended by the pupils under such an agreement shall, not later than July 2 of each year, certify, to the county superintendent of schools having jurisdiction over the school district of residence of the pupils, the average daily attendance of the pupils of the district attending the schools of the school district in the adjoining state. Certification shall be made on forms furnished by the Superintendent of Public Instruction. The county superintendent of schools shall report the average daily attendance to the Superintendent of Public Instruction, who shall include the average daily attendance in his report of average daily attendance in all of the duly established schools of the state for the last preceding school year certified by him to the State Controller.