Cal. Rev. & Tax. Code § 280

Commencing on or after July 1, an audit of the exemptions granted pursuant to subdivision (o), (p), (q) or (r) of Section 3, Article XIII of the Constitution shall be conducted by the auditor. The audit shall cover such exemptions claimed for the current tax year as well as any prior tax years in respect to which escaped assessments would be timely pursuant to Section 532.