Neb. Rev. Stat. § 23-2306.02

Under such rules and regulations as the retirement board may adopt and promulgate, a full-time or part-time employee of a city, village, or township who becomes a county employee pursuant to a merger of services may pay to the retirement system an amount equal to the sum of all deductions which were made from the employee's compensation, plus earnings, during such period of employment with the city, village, or township. Payment shall be made within five years after the merger or prior to retirement, whichever comes first, and may be made through direct payment, installment payments, or an irrevocable payroll authorization.