Where to File a Petition for Change of Name. Petitions may be filed at the Daley Center or at any of the five suburban court locations.Every person authorized to request a correction must complete an Affidavit and Certificate of Correction Request. Obtain and complete the following forms on the Lake County Circuit Clerk website under the section titled "Name Change". What is an Affidavit of Identity? To obtain a legal name change in Illinois, an applicant who has resided in the state for at least six months must submit a petition to the court. Change of name proceedings, Federal and State tax liens against persons whose names are the same as affiant or similar thereto. As you begin the process, consider the sample name change petition and supporting documents included in the. Related Links part at the end of this section. To obtain a legal name change in Illinois, an applicant who has resided in the state for at least six months must submit a petition to the court.