California Code, Health and Safety Code - HSC § 1374.22

(a) The written notice described in subdivision (a) of Section 1374.21 shall be delivered by mail at the last known address at least 60 days prior to the renewal effective date to the group contract holder.

(b) The written notice shall state in italics and in 12-point type the actual dollar amount and the specific percentage of the premium rate increase. Further, the notice shall describe in plain understandable English and highlighted in italics any changes in the plan design or change in benefits with reduction in benefits, waivers, exclusions, or conditions.

(c) The written notice shall specify in a minimum of 10-point bold typeface the reason or reasons for premium rate changes, plan design, or plan benefit changes.