(a) Each notice shall set forth the reasons for the proposed deficiency assessment and the computation thereof.
(b) Each notice shall include the date determined by the Franchise Tax Board as the last day on which the taxpayer may file a written protest pursuant to Section 19041. Failure to include this date shall not invalidate a notice that is otherwise valid.
(c) The amendments made by the act adding this subdivision shall apply to any notice mailed after December 31, 1999.