If, in accordance with the General Appropriations Act, the administrative head or heads of an agency or institution authorize payment for emergency leave to an employee receiving workers' compensation benefits, the payments may not exceed an amount equal to the difference between the basic monthly wage of the employee and the amount of benefits received and may not extend beyond six months from the date on which compensation payments begin. In authorizing these payments for emergency leave, the administrative head or heads of the agency or institution must review the merits of each case individually. If payment for emergency leave is authorized, the agency or institution shall attach a statement of the reasons for the authorization to its duplicate payroll voucher for the first payroll period affected by the leave.