(1) Commencing October 1, 1988, the retirement board shall determine an adjusted supplemental retirement benefit to reflect changes in the cost of living and wage levels that have occurred subsequent to the date of retirement for each person who is retired from the School Employees Retirement System of the State of Nebraska or from the retirement system for Class V school districts as provided by the Class V School Employees Retirement Act with twenty-five or more years of creditable service as of October 1, 1988.

(2) For each person who qualifies under subsection (1) of this section, the retirement board shall determine the value of the total monthly benefit being received from the School Employees Retirement System of the State of Nebraska or from the retirement system for Class V school districts as provided by the Class V School Employees Retirement Act and the supplemental benefit provided by section 79-942 if applicable. From two hundred fifty dollars, the board shall subtract the total monthly benefit. Such difference, if positive, shall be the adjusted supplemental retirement benefit and shall be paid to the retired person each month, except that if this difference is less than five dollars, a minimum payment of five dollars per month shall be made to such person. The adjusted supplemental retirement benefit shall be paid to a retired person during his or her life.

(3) The retirement board may buy a paid-up annuity for a retired person which guarantees the adjusted supplemental retirement benefit provided under this section.

(4) The adjusted supplemental retirement benefit provided under this section shall be funded from the Contingent Account but only from such income that is attributable to employer and employee contributions.