10 ILCS 5/8-8.1
In the designation of the name of a candidate on a petition for nomination, the candidate's given name or names, initial or initials, a nickname by which the candidate is commonly known, or a combination thereof, may be used in addition to the candidate's surname. If a candidate has changed his or her name, whether by a statutory or common law procedure in Illinois or any other jurisdiction, within 3 years before the last day for filing the petition for that office, then (i) the candidate's name on the petition must be followed by "formerly known as (list all prior names during the 3-year period) until name changed on (list date of each such name change)" and (ii) the petition must be accompanied by the candidate's affidavit stating the candidate's previous names during the period specified in (i) and the date or dates each of those names was changed; failure to meet these requirements shall be grounds for denying certification of the candidate's name for the ballot or removing the candidate's name from the ballot, as appropriate, but these requirements do not apply to name changes resulting from adoption to assume an adoptive parent's or parents' surname, marriage or civil union to assume a spouse's surname, or dissolution of marriage or civil union or declaration of invalidity of marriage or civil union to assume a former surname or a name change that conforms the candidate's name to his or her gender identity. No other designation such as a political slogan, title, or degree, or nickname suggesting or implying possession of a title, degree or professional status, or similar information may be used in connection with the candidate's surname.
10 ILCS 5/8-8.1