California Code, Education Code - EDC § 48260

(a) A pupil subject to compulsory full-time education or to compulsory continuation education who is absent from school without a valid excuse three full days in one school year or tardy or absent for more than a 30-minute period during the schoolday without a valid excuse on three occasions in one school year, or any combination thereof, shall be classified as a truant and shall be reported to the attendance supervisor or to the superintendent of the school district.

(b) Notwithstanding subdivision (a), it is the intent of the Legislature that school districts shall not change the method of attendance accounting provided for in existing law and shall not be required to employ period-by-period attendance accounting.

(c) For purposes of this article, a valid excuse includes, but is not limited to, the reasons for which a pupil shall be excused from school pursuant to Sections 48205 and 48225.5 and may include other reasons that are within the discretion of school administrators and, based on the facts of the pupil's circumstances, are deemed to constitute a valid excuse.