Any person who is an employee of the state, having prior service upon the date of the establishment of the retirement system, within the period of thirty (30) days next succeeding such establishment, and any person having prior service on leave from the service of the state, within thirty (30) days next succeeding the termination of such leave, may file with the board, on forms prescribed by it, a notice of his election not to be included in the membership of the retirement system, and in such cases, the board shall exclude him from membership. Any employee so excluded, however, may thereafter become a member by making application for membership to the board, but no such employee shall receive any prior service credit.
T.C.A. § 8-3412