(a) Investment fund options under subdivision (a) of Section 21672 shall be provided through a written interagency agreement between the board and the Department of Human Resources.
(b) Except for investments made pursuant to subdivision (a), participating employers shall enter into a written contractual agreement with the board.
(c) Participants shall enter into contractual agreements that are required to effectuate participation in a tax-preferred retirement savings program, including employees participating under a program described in subdivision (a) or (b) of Section 21671, or any other program that provides for the deferral of compensation program or written salary reduction agreements with their employers, for the purpose of making deferrals or for annuity contracts.