(1) The retirement system may accept cash rollover contributions from a member who is making payment pursuant to section 23-2306.02, 23-2306.03, 23-2320, or 23-2323.01 if the contributions do not exceed the amount authorized to be paid by the member pursuant to section 23-2306.02, 23-2306.03, 23-2320, or 23-2323.01, and the contributions represent (a) all or any portion of the balance of the member's interest in a qualified plan under section 401(a) of the Internal Revenue Code or (b) the interest of the member from an individual retirement account or an individual retirement annuity, the entire amount of which is attributable to a qualified total distribution, as defined in the Internal Revenue Code, from a qualified plan under section 401(a) of the code and qualified as a tax-free rollover amount. The member's interest under subdivision (a) or (b) of this subsection must be transferred to the retirement system within sixty days from the date of the distribution from the qualified plan, individual retirement account, or individual retirement annuity.

(2) Cash transferred to the retirement system as a rollover contribution shall be deposited as other payments made under section 23-2306.02, 23-2306.03, 23-2320, or 23-2323.01.

(3) Under the same conditions as provided in subsection (1) of this section, the retirement system may accept eligible rollover distributions from (a) an annuity contract described in section 403(b) of the Internal Revenue Code, (b) a plan described in section 457(b) of the code which is maintained by a state, a political subdivision of a state, or any agency or instrumentality of a state or political subdivision of a state, or (c) the portion of a distribution from an individual retirement account or annuity described in section 408(a) or 408(b) of the code that is eligible to be rolled over and would otherwise be includable in gross income. Amounts accepted pursuant to this subsection shall be deposited as all other payments under this section.

(4) The retirement system may accept direct rollover distributions made from a qualified plan pursuant to section 401(a)(31) of the Internal Revenue Code. The direct rollover distribution shall be deposited as all other payments under this section.

(5) The board may adopt and promulgate rules and regulations defining procedures for acceptance of rollovers which are consistent with sections 401(a)(31) and 402 of the Internal Revenue Code.