735 ILCS 5/4-220
Within 3 days after the return day of summonsif personally served 10 days before the day on which it is returnable, or within 13 days after such return day, if personally served less than 10 days prior thereto, or if not personally served, then within the time prescribed in the published noticethe owner or any person interested adversely to the claims mentioned in the notice, unless on cause shown, further time shall be allowed by the court, shall plead to the complaint as in other civil cases. If an answer is filed, the answer shall respond completely and distinctly to each allegation of the complaint, and shall be supported by affidavit. If no such answer or motion, together with an affidavit is filed within the time above specified, the plaintiff is entitled to an order of default, and the claim may be proved and judgment entered as in other civil cases.
735 ILCS 5/4-220