(1) Beginning July 1, 2011, and each July 1 thereafter, the board shall determine the number of retired members or beneficiaries described in subdivision (4)(b) of this section in the retirement system and an annual benefit adjustment shall be made by the board for each retired member or beneficiary under one of the cost-of-living adjustment calculation methods found in subsection (2), (3), or (4) of this section. Each retired member or beneficiary, if eligible, shall receive an annual benefit adjustment under the cost-of-living adjustment calculation method that provides the retired member or beneficiary the greatest annual benefit adjustment increase. No retired member or beneficiary shall receive an annual benefit adjustment under more than one of the cost-of-living adjustment calculation methods provided in this section.

(2) The current benefit paid to a retired member or beneficiary under this subsection shall be adjusted so that the purchasing power of the benefit being paid is not less than sixty percent of the purchasing power of the initial benefit. The purchasing power of the initial benefit in any year following the year in which the initial benefit commenced shall be calculated by dividing the United States Department of Labor, Bureau of Labor Statistics, Consumer Price Index for Urban Wage Earners and Clerical Workers factor on June 30 of the current year by the Consumer Price Index for Urban Wage Earners and Clerical Workers factor on June 30 of the year in which the benefit commenced. The result shall be multiplied by the product that results when the amount of the initial benefit is multiplied by sixty percent. In any year in which applying the adjustment provided in subsection (3) of this section results in a benefit which would be less than sixty percent of the purchasing power of the initial benefit as calculated in this subsection, the adjustment shall instead be equal to the percentage change in the Consumer Price Index for Urban Wage Earners and Clerical Workers factor from the prior year to the current year.

(3) The current benefit paid to a retired member or beneficiary under this subsection shall be increased annually by the lesser of (a) the percentage change in the Consumer Price Index for Urban Wage Earners and Clerical Workers for the period between June 30 of the prior year to June 30 of the present year or (b) two and one-half percent.

(4)(a) The current benefit paid to a retired member or beneficiary under this subsection shall be calculated by multiplying the retired member's or beneficiary's total monthly benefit by the lesser of (i) the cumulative change in the Consumer Price Index for Urban Wage Earners and Clerical Workers from the last adjustment of the total monthly benefit of each retired member or beneficiary through June 30 of the year for which the annual benefit adjustment is being calculated or (ii) an amount equal to three percent per annum compounded for the period from the last adjustment of the total monthly benefit of each retired member or beneficiary through June 30 of the year for which the annual benefit adjustment is being calculated.

(b) In order for a retired member or beneficiary to receive the cost-of-living adjustment calculation method in this subsection, the retired member or beneficiary shall be (i) a retired member or beneficiary who has been receiving a retirement benefit for at least five years if the member had at least twenty-five years of creditable service, (ii) a member who has been receiving a disability retirement benefit for at least five years pursuant to section 81-2025, or (iii) a beneficiary who has been receiving a death benefit pursuant to section 81-2026 for at least five years, if the member's or beneficiary's monthly accrual rate is less than or equal to the minimum accrual rate as determined by this subsection.

(c) The monthly accrual rate under this subsection is the retired member's or beneficiary's total monthly benefit divided by the number of years of creditable service earned by the retired or deceased member.

(d) The total monthly benefit under this subsection is the total benefit received by a retired member or beneficiary pursuant to the Nebraska State Patrol Retirement Act and previous adjustments made pursuant to this section or any other provision of the act that grants a benefit or cost-of-living increase, but the total monthly benefit shall not include sums received by an eligible retired member or eligible beneficiary from federal sources.

(e) Beginning July 1, 2010, the minimum accrual rate under this subsection was forty dollars and sixteen cents. Beginning July 1, 2011, the minimum accrual rate under this subsection was forty-one dollars and seventy-nine cents. Beginning July 1, 2012, the minimum accrual rate under this subsection was forty-two dollars and forty-five cents. Beginning July 1, 2013, the board shall annually adjust the minimum accrual rate to reflect the cumulative percentage change in the Consumer Price Index for Urban Wage Earners and Clerical Workers from the last adjustment of the minimum accrual rate.

(5) Beginning July 1, 2011, and each July 1 thereafter, each retired member or beneficiary shall receive the sum of the annual benefit adjustment and such retiree's total monthly benefit less withholding, which sum shall be the retired member's or beneficiary's adjusted total monthly benefit. Each retired member or beneficiary shall receive the adjusted total monthly benefit until the expiration of the annuity option selected by the member or until the retired member or beneficiary again qualifies for the annual benefit adjustment, whichever occurs first.

(6) The annual benefit adjustment pursuant to this section shall not cause a current benefit to be reduced, and a retired member or beneficiary shall never receive less than the adjusted total monthly benefit until the annuity option selected by the member expires.

(7) The board shall adjust the annual benefit adjustment provided in this section so that the cost-of-living adjustment provided to the retired member or beneficiary at the time of the annual benefit adjustment does not exceed the change in the Consumer Price Index for Urban Wage Earners and Clerical Workers for the period between June 30 of the prior year to June 30 of the present year. If the consumer price index used in this section is discontinued or replaced, a substitute index published by the United States Department of Labor shall be selected by the board which shall be a reasonable representative measurement of the cost-of-living for retired employees.

(8) This section applies to an officer who became a member prior to July 1, 2016.