(1) Any contributing member may purchase service credit for time he or she was on a leave of absence authorized by the school board or board of education of the school district by which he or she was employed at the time of such leave of absence or pursuant to any contractual agreement entered into by such school district. Such credit shall increase the benefits provided by the retirement system and shall be included in creditable service when determining eligibility for death, disability, termination of employment, and retirement benefits. The amount to be paid by the member for such service credit shall equal the actuarial cost to the retirement system for allowing such additional service credit to the employee. Payment shall be completed within five years after such member's election to purchase service credit or prior to termination of employment, whichever occurs first, and may be made through direct payment, installment payments, or an irrevocable payroll deduction authorization.
(2) Leave of absence shall be construed to include, but not be limited to, sabbaticals, maternity leave, exchange teaching programs, full-time leave as an elected official of a professional association or collective-bargaining unit, or leave of absence to pursue further education or study. Such leave shall not exceed four years in length, and in order to receive credit for the leave of absence the member must return to employment with a school district, other than a Class V school district, in the state within one year after termination of the leave of absence.
(3) Compensation for the period of service purchased shall not be included in determining the member's final average compensation.