(a) An employer annually shall certify to the board of trustees the beginning date of the contract of each member whose contract year begins after June 30 and continues after August 31 of the same calendar year.
(b) For school years after the 1994-1995 school year, an employer annually shall certify to the board of trustees the beginning date of an oral or written work agreement that begins after June 30 and continues after August 31 of the same calendar year.
(c) Each reporting district shall cooperate with the retirement system in ascertaining a member's annual earnings during any year. The board of trustees by rule may prescribe the form of and procedures for filing certifications required by this section.