Neb. Rev. Stat. §§ 79-913
All school employees not required to hold a certificate, diploma, or credentials to practice in a professional capacity who are employed after January 1, 1978, and prior to July 1, 1978, shall have until June 30, 1978, to file with the retirement board an election not to be included in the membership of the retirement system established pursuant to the School Employees Retirement Act. The election shall be in writing on forms prescribed by the retirement board, and any person so electing waives all rights within the system except to a refund of his or her accumulated contributions. All such employees employed on or after July 1, 1978, shall become members of such retirement system as soon as they are employed and shall not have a right to elect out of such retirement system.
Neb. Rev. Stat. §§ 79-913