(1) A county employees retirement system shall be established for the purpose of providing a retirement annuity or other benefits for employees as provided by the County Employees Retirement Act. It shall be known as the Retirement System for Nebraska Counties, and by such name shall transact all business and hold all cash and other property as provided in the County Employees Retirement Act.
(2) The retirement system shall not accept as contributions any money from members or participating counties except the following:
(a) Mandatory contributions and fees established by sections 23-2307 and 23-2308;
(b) Payments on behalf of transferred employees made pursuant to section 23-2306.02 or 23-2306.03;
(c) Money that is a repayment of refunded contributions made pursuant to section 23-2320;
(d) Contributions for military service credit made pursuant to section 23-2323.01;
(e) Actuarially required contributions pursuant to subdivision (4)(b) of section 23-2317;
(f) Trustee-to-trustee transfers pursuant to section 23-2323.04;
(g) Corrections ordered by the board pursuant to section 23-2305.01; or
(h) Payments made pursuant to subsection (4) of section 23-2306.