35 ILCS 200/21-170
On the day on which application for judgment on delinquent property is applied for, the collector, assisted by the county clerk, shall post all payments compare and correct the list, and shall make and subscribe an affidavit, which shall be substantially in the following form:
State of Illinois)) ss. County of .......) I ...., collector of the county of ...., do solemnly swear (or affirm, as the case may be), that the foregoing is a true and correct list of the delinquent property within the county of ...., upon which I have been unable to collect the taxes (and special assessments, interest, and printer's fees, if any), charged thereon, as required by law, for the year or years therein set forth; and that the taxes now remain due and unpaid, to the best of my knowledge and belief. Dated ..........
The affidavit shall be entered at the end of the list, and signed by the collector.
35 ILCS 200/21-170