(1) The retirement annuity of a judge who is an original member, who has not made the election provided for in section 24-710.01, and who retires under section 24-708 or 24-709 shall be computed as follows: Each such judge shall be entitled to receive an annuity, each monthly payment of which shall be in an amount equal to three and one-third percent of his or her final average compensation as such judge, multiplied by the number of his or her years of creditable service. The amount stated in this section shall be supplemental to any benefits received by such judge under the Nebraska and federal old age and survivors' insurance acts at the date of retirement, but the monthly combined benefits received thereunder and by the Judges Retirement Act shall not exceed sixty-five percent of the final average compensation such judge was receiving when he or she last served as such judge. The amount of retirement annuity of a judge who retires under section 24-708 or 24-709 shall not be less than twenty-five dollars per month if he or she has four years or more of service credit.

(2) The retirement annuity of a judge who is a future member and who retires after July 1, 1986, under section 24-708 or 24-709 shall be computed as follows: Each such judge shall be entitled to receive an annuity, each monthly payment of which shall be in an amount equal to three and one-half percent of his or her final average compensation as such judge, multiplied by the number of his or her years of creditable service, except that prior to an actuarial factor adjustment for purposes of calculating an optional form of annuity benefits under subsection (3) of this section, the monthly benefits received under this subsection shall not exceed seventy percent of the final average compensation such judge was receiving when he or she last served as such judge.

(3) Except as provided in section 42-1107, any member may, when filing an application as provided by the retirement system, elect to receive, in lieu of the normal form annuity benefits to which the member or his or her beneficiary may otherwise be entitled under the Judges Retirement Act, an optional form of annuity benefits which the board may by rules and regulations provide, the value of which, determined by accepted actuarial methods and on the basis of actuarial assumptions recommended by the actuary, approved by the board, and kept on file in the office of the director, is equal to the value of the benefit replaced. The board may (a) adopt and promulgate appropriate rules and regulations to establish joint and survivorship annuities, with and without reduction on the death of the first annuitant, and such other forms of annuities as may in its judgment be appropriate and establishing benefits as provided in sections 24-707 and 24-707.01, (b) prescribe appropriate forms for making the election by the members, and (c) provide for the necessary actuarial services to make the required valuations.

(4) A one-time cost-of-living adjustment shall be made for each retired judge and each surviving beneficiary who is receiving a retirement annuity as provided for in this section. The annuity shall be adjusted by the increase in the cost of living or wage levels between the effective date of retirement and June 30, 1992, except that such increases shall not exceed three percent per year of retirement and the total increase shall not exceed two hundred fifty dollars per month.