(a) The monthly retirement benefit payable to retirants and beneficiaries of the Arkansas Teacher Retirement System who were retired on or before July 1, 1978, and who were receiving benefits on July 1, 1979, shall be increased as follows:
(1) For all benefits to retirants and beneficiaries of the system whose total credited service is before July 1, 1961, a monthly benefit increase equal to one dollar ($1.00) per each year of credited service;
(2) For all benefits to retirants and beneficiaries of the system which are based in whole or in part upon credited service rendered after July 1, 1961, a monthly benefit increase equal to seventy-five cents (75¢) per each year of credited service;
(3) For benefit increases authorized by subdivisions (a)(1) and (2) of this section, fractional years of service shall be disregarded, and the increase shall be added to the monthly annuity after the annual postretirement increase based on the consumer price index has been applied to the retirant's base annuity; and
(4) In the event that there is more than one (1) beneficiary or survivor of a member or retirant receiving benefits, the increases in subdivisions (a)(1) and (2) of this section shall be based upon the member's total credited service. The benefit increase so determined shall be divided between the survivors or beneficiaries in proportion to their base annuities.
(b) For retirements effective after July 1, 1978, for which a monthly benefit is payable for the month of July 1981 or later, calculations shall be made as provided in subdivisions (b)(1) and (2) of this section. If the monthly benefit calculated using subdivision (b)(1) of this section is more than the monthly benefit calculated using subdivision (b)(2) of this section, then the difference shall be paid to the retirant as a monthly benefit increase, subject to the provisions of subdivisions (b)(3)-(6) of this section, as follows:
(1) Calculate the monthly annuity payable to the member under § 24-7-705, based on the provisions of § 24-7-705, his or her salary record, and his or her service record, all as of July 1, 1978, and add seventy-five cents (75¢) for each year of the member's credited service rendered before July 1, 1978;
(2) Calculate the monthly annuity payable to the member under the provisions of § 24-7-705 in effect at the time of the member's retirement;
(3) For benefit increases authorized by this subsection, fractional years of service shall be disregarded. The increase shall be added to the monthly annuity after the annual postretirement increase based on the consumer price index has been applied to the retirant's base annuity;
(4) In the event that there is more than one (1) beneficiary or survivor of a member or retirant receiving benefits, the increases in this subsection shall be based upon the member's total credited service, and the benefit increase so determined shall be divided between the survivors or beneficiaries in proportion to their base annuities;
(5) Any benefit increase created by this subsection shall be effective at retirement but not for any month before July 1981; and
(6) If there is any change in § 24-7-705 after the member's retirement, the amount under subdivision (b)(2) of this section shall be recalculated using the changed provisions, and the benefit increase provided by this subsection shall be changed correspondingly.