35 ILCS 200/9-100
Before January 1 in each year of the general assessment, as provided in Sections 9-215 through 9-225, each county clerk shall make up the list of property to be assessed for taxes for the townships or taxing districts in the county, in books for that purpose. Annually, before January 1, he or she shall make up lists of properties which are taxable, or which become taxable for the first time, and which are not already listed, and make up lists of properties which have been subdivided and not listed by the proper description. The county clerk shall enter in the proper column, opposite the respective parcels, the name of the owner, or other such persons, so far as he is able to ascertain the names. The lists shall contain columns to show the number of acres or lots improved, and the assessed value; the assessed value of improvements; the total value; and other information as may be required. The county clerk shall also have prepared and ready for delivery all blanks necessary in the assessment of property, and shall deliver those blanks to the assessors along with the assessment books or lists. The books or lists may be completed and delivered by townships or taxing districts without waiting for the completion of all the books or lists, but all assessment books or lists shall be delivered by the county clerk to the chief county assessment officer on or before January 1. The books or lists shall be made in duplicate.
35 ILCS 200/9-100