Cal. Rev. & Tax. Code § 8782

Except in the case of fraud, intent to evade the tax, or failure to make a return, every notice of a deficiency determination shall be served within three years after the last day of the calendar month following the period for which the return was due or within three years after the return is filed, whichever period expires later. If the user fails to make a return, the notice of determination shall be served within eight years after the last day of the month following the period for which the return was due.