55 ILCS 5/2-3008
Determination of method of compensation of members of county board. At the time it reapportions its county under this Division, the county board shall determine whether the salary to be paid the members to be elected shall be computed on a per diem basis, on an annual basis or on a combined per diem and annual basis, and shall fix the amount of that salary. If the county board desires before the next reapportionment to change the basis of payment or amount of compensation after fixing those items, it may do so by ordinance or by resolution. Those changes shall not however, take effect during the term for which an incumbent county board member has been elected. In addition, the county board shall determine the amount of any additional compensation for the chairman of the county board. The county board may adjust that additional compensation at any time adjustments in the salary of board members may be made. Those adjustments shall not however, take effect during the term for which the incumbent chairman of the county board has been elected.
55 ILCS 5/2-3008