California Code, Penal Code - PEN § 26312

(a) Notice of a temporary revocation shall be effective upon personal service or upon receipt of a notice that was sent by first-class mail, postage prepaid, return receipt requested, to the retiree's last known place of residence.

(b) The retiree shall have 15 days to respond to the notification and request a hearing to determine if the temporary revocation should become permanent.

(c) A retired peace officer who fails to respond to the notice of hearing within the 15-day period shall forfeit the right to a hearing and the authority of the officer to carry a firearm shall be permanently revoked.  The retired officer shall immediately return the identification certificate to the issuing agency.

(d) If a hearing is requested, good cause for permanent revocation shall be determined at a hearing, as specified in Section 26320.  The hearing shall be held no later than 120 days after the request by the retired officer for a hearing is received.

(e) A retiree may waive the right to a hearing and immediately return the identification certificate to the issuing agency.