10 ILCS 5/4-16
Any registered voter who changes his residence from one address to another within the same county wherein this Article is in effect, may have his registration transferred to his new address by making and signing an application for change of residence address upon a form to be provided by the county clerk. Such application must be made to the office of the county clerk and may be made either in person or by mail. In case the person is unable to sign his name, the county clerk shall require him to execute the application in the presence of the county clerk or of his properly authorized representative, by his mark, and if satisfied of the identity of the person, the county clerk shall make the transfer.
Upon receipt of the application, the county clerk, or one of his employees deputized to take registrations shall cause the signature of the voter and the data appearing upon the application to be compared with the signature and data on the registration record card, and if it appears that the applicant is the same person as the person previously registered under that name the transfer shall be made.
No transfers of registration under the provisions of this Section shall be made during the 27 days preceding any election at which such voter would be entitled to vote. When a removal of a registered voter takes place from one address to another within the same precinct within a period during which a transfer of registration cannot be made before any election or primary, he shall be entitled to vote upon presenting the judges of election his affidavit substantially in the form prescribed in Section 17-10 of this Act of a change of residence address within the precinct on a date therein specified.
The county clerk may obtain information from utility companies, city, village, incorporated town and township records, the post office, or from other sources, regarding the removal of registered voters, and may treat such information, and information procured from his death and marriage records on file in his office, as an application to erase from the register any name concerning which he may so have information that the voter is no longer qualified to vote under the name, or from the address from which registered, and give notice thereof in the manner provided by Section 4--12 of this Article, and notify voters who have changed their address that a transfer of registration may be made in the manner provided in this Section enclosing a form therefor.
If any person be registered by error in a precinct other than that in which he resides, the county clerk may transfer his registration to the proper precinct, and if the error is or may be on the part of the registration officials, and is disclosed too late before an election or primary to mail the certificate required by Section 4--15, such certificate may be personally delivered to the voter and he may vote thereon as therein provided, but such certificates so issued shall be specially listed with the reason for the issuance thereof.
Where a revision or rearrangement of precincts is made by the county board, the county clerk shall immediately transfer to the proper precinct the registration of any voter affected by such revision or rearrangement of the precinct; make the proper notations on the registration cards of a voter affected by the revision or rearrangement and shall issue revised certificates to each registrant of such change.
Any registered voter who changes his or her name by marriage or otherwise shall be required to register anew and authorize the cancellation of the previous registration; but if the voter still resides in the same precinct the elector may, if otherwise qualified, vote upon making an affidavit at the polling place attesting that the voter is the same person who is registered to vote under his or her former name. The affidavit shall be treated by the election authority as authorization to cancel the registration under the former name, and the election authority shall register the person under his or her current name.
The precinct election officials shall report to the county clerk the names and addresses of all persons who have changed their addresses and voted, which shall be treated as an application to change address accordingly, and the names and addresses of all persons otherwise voting by affidavit as in this Section provided, which shall be treated as an application to erase under Section 4--12 hereof.
10 ILCS 5/4-16