Missouri Revised Statutes Title XI. Education and Libraries § 169.589. Discharge from Armed Forces, defined--members may elect to pay contribution to system for service time--reemployment by school district, contribution by district to be paid, when

1. A member of the system established by sections 169.010 to 169.141 or sections 169.600 to 169.715 who entered the uniformed services of the United States of America, and who is reemployed pursuant to the Uniformed Services Employment and Reemployment Rights Act of 1994,  1 or any subsequent revisions, shall be deemed to have been an employee for purposes of vesting and because of qualifying service in the uniformed services of the United States shall not be subject to the provisions of subsection 4 of section 169.050 or subsection 3 of section 169.650 with regard to termination of membership. In addition, such a member may elect within the period allowed by the Uniformed Services Employment and Reemployment Rights Act of 1994 to pay the contributions the member would have paid but for service in the uniformed services. Upon completing payment, the member shall be entitled at retirement to payment of benefits based on the period of service. When a member has elected to make contributions as described in this section, the school district reemploying the member shall pay the employer contributions it would have paid with respect to the individual, with interest. The board of trustees of the retirement system may adopt rules for administration of this section consistent with the Uniformed Services Employment and Reemployment Rights Act of 1994.

2. For the purposes of this chapter, “discharge from the Armed Forces” means the final date of discharge and shall not mean the last day of active duty.