40 ILCS 5/9-186
In each year, the board shall conduct a regular election, under rules adopted by it, at least 30 days prior to the expiration of the term of each elected employee or annuitant member.
To be eligible to be a county employee member, a person must be an employee of the county and must have at least 5 years of service credit in that capacity by December 1 of the year of election. To be eligible to be a forest preserve district member, a person must be an employee of the forest preserve district and must have at least 5 years of service credit in that capacity by December 1 of the year of election.
Only those persons who are employees of the county shall be eligible to vote for the 3 county employee members, only those persons who are employees of the forest preserve district shall be eligible to vote for the forest preserve district member, only those persons who are currently receiving retirement benefits under this Article shall be eligible to vote for the annuitant members elected under subsections (d) and (d-1) of Section 9-185, and only those persons who are currently receiving retirement benefits under Article 10 shall be eligible to vote for the forest preserve district annuitant member elected under subsection (f) of Section 9-185. The ballot shall be of secret character.
Except as otherwise provided in Section 9-187, each member of the board shall hold office until his successor is chosen and has qualified.
Any person elected or appointed a member of the board shall qualify for the office by taking an oath of office to be administered by the county clerk or a person designated by him. A copy thereof shall be kept in the office of the county clerk. Any appointment or notice of election shall be in writing and the written instrument shall be filed with the oath.
40 ILCS 5/9-186