California Code, Government Code - GOV § 31755.1

(a)(1) The Board of Supervisors of Contra Costa County may, pursuant to a memorandum of understanding in accordance with the Meyers-Milias-Brown Act (Chapter 10 (commencing with Section 3500) of Division 4 of Title 1), adopt a resolution making this section applicable to the officers and employees of the county specified in the resolution and specifying the future operative date of its application.

(2) After the board of supervisors has adopted that resolution, the governing body of a district may make this section applicable to its officers and employees by adopting a resolution specifying the future operative date of its application, which date may not be earlier than the operative date of the resolution described in paragraph (1).

(b)(1) Except as otherwise provided in this section, Tier Three, as described in Section 31755, shall apply to all officers and employees who become members or return to membership in the county or district, and with respect to service performed, on or after the date this section becomes applicable in the county or district.

(2) On the date this section becomes applicable in the county or district, those officers and employees specified in the resolution described in subdivision (a) and then-subject to Tier Two shall thereafter be covered by Tier Three, as described in Section 31755, for service performed on and after that date.