Section 23-604 - Annual payroll and average annual payrollA. "Annual payroll" means the total amount of wages for employment paid by an employer during a twelve-month period ending on June 30 of any calendar year.B. In computing an employer's contribution rate, "average annual payroll" means:1. The annual payroll for the twelve-month period immediately preceding the computation date for an employer whose account has been chargeable with benefits for twelve but less than twenty-four months.2. The average of the annual payrolls for the last two twelve-month periods immediately preceding the computation date for an employer whose account has been chargeable with benefits for twenty-four but less than thirty-six months.3. The average of the annual payrolls for the last three twelve-month periods immediately preceding the computation date for an employer whose account has been chargeable with benefits for thirty-six or more months.C. "Computation date" means July 1 of each calendar year with respect to rates of contribution applicable to the calendar year beginning with the following January 1.