(10 ILCS 5/25-2) (from Ch. 46, par. 25-2)
    Sec. 25-2. Events on which an elective office becomes vacant. Every elective office shall become vacant on the happening of any of the following events before the expiration of the term of such office:
        (1) The death of the incumbent.
        (2) His or her resignation.
        (3) His or her becoming a person under legal
        (4) His or her ceasing to be an inhabitant of the
State; or if the office is local, his or her ceasing to be an inhabitant of the district, county, town, or precinct for which he or she was elected; provided, that the provisions of this paragraph shall not apply to township officers whose township boundaries are changed in accordance with Section 10-20 of the Township Code, to a township officer after disconnection as set forth in Section 15-17 of the Township Code, nor to township or multi-township assessors elected under Sections 2-5 through 2-15 of the Property Tax Code.
        (5) His or her conviction of an infamous crime, or of
any offense involving a violation of official oath.
        (6) His or her removal from office.
        (7) His or her refusal or neglect to take his or her
oath of office, or to give or renew his or her official bond, or to deposit or file such oath or bond within the time prescribed by law.
        (8) The decision of a competent tribunal declaring
his or her election void.
    No elective office, except as herein otherwise provided, shall become vacant until the successor of the incumbent of such office has been appointed or elected, as the case may be, and qualified.
    An unconditional resignation, effective at a future date, may not be withdrawn after it is received by the officer authorized to fill the vacancy. Such resignation shall create a vacancy in office for the purpose of determining the time period which would require an election. The resigning office holder may continue to hold such office until the date or event specified in such resignation, but no later than the date at which his or her successor is elected and qualified.
    An admission of guilt of a criminal offense that would, upon conviction, disqualify the holder of an elective office from holding that office, in the form of a written agreement with State or federal prosecutors to plead guilty to a felony, bribery, perjury, or other infamous crime under State or federal law, shall constitute a resignation from that office, effective at the time the plea agreement is made.
    For purposes of this Section, a conviction for an offense that disqualifies the holder of an elective office from holding that office shall occur on the date of the return of a guilty verdict or, in the case of a trial by the court, the entry of a finding of guilt.
    This Section does not apply to any elected or appointed officers or officials of any municipality having a population under 500,000.
(Source: P.A. 94-529, eff. 8-10-05; 95-646, eff. 1-1-08.)