Cal. Bus. & Prof. Code § 5661
All accusations against a licensee shall be filed within three years after the board discovers, or through the use of reasonable diligence should have discovered, the act or omission alleged as the ground for disciplinary action or within six years after the act or omission alleged as the ground for disciplinary action, whichever occurs first. However, with respect to an accusation alleging a violation of Section 5667, the accusation may be filed within three years after the discovery by the board of the alleged facts constituting the fraud or misrepresentation prohibited by Section 5667.
If any accusation is not filed within the time provided in this section, no action against a licensee shall be commenced under this article.
Ca. Bus. and Prof'l. Code § 5661