Before entering office, every assessor or supervisor of assessments shall take and subscribe to the following oath, which shall be filed in the office of the county clerk, except the oath of township or multi-township assessors and their deputies shall be filed with their respective town clerks. The oath shall be as follows:
State of Illinois))ss. County of ...........) I do solemnly swear (or affirm) that I will support the Constitution of the United States and the Constitution of the State of Illinois; and that I will faithfully discharge all the duties of the office of assessor, or supervisor of assessments to the best of my ability. Dated..........
35 ILCS 200/4-30