35 ILCS 200/22-15
The purchaser or his or her assignee shall give the notice required by Section 22-10 by causing it to be published in a newspaper as set forth in Section 22-20. In addition, the notice shall be served upon owners who reside on any part of the subject property by leaving a copy of the notice with those owners personally. The notice must be served by a sheriff (or if he or she is disqualified, by a coroner) of the county in which the property, or any part thereof, is located or, by a person who is licensed or registered as a private detective under the Private Detective, Private Alarm, Private Security, Fingerprint Vendor, and Locksmith Act of 2004 .
In counties of 3,000,000 or more inhabitants, if the notice required by Section 22-10 is to be served by the sheriff, no sale in error may be declared pursuant to Section 22-50 or subparagraph (5) of subsection (a) of Section 21-310 based upon the sheriff's failure to serve the notice in accordance with this Section unless the notice and service list for the first service attempt is delivered by the purchaser or assignee to the sheriff at least 5 months prior to the expiration of the period of redemption. Purchasers or assignees may request that the sheriff make additional service attempts to the same entities and locations, and the sheriff may make those additional attempts within the noticing period established in Section 22-10, but the sheriff's failure to make such additional service attempts is not grounds for a sale in error under Section 22-50 or subparagraph (5) of subsection (a) of Section 21-310.
In counties of 3,000,000 or more inhabitants, if the purchaser or assignee requests that the sheriff make an additional service attempt upon an entity or to a location that was not included on the service list for the first attempt, then the purchaser or assignee must deliver the notice and service list for the additional service attempt to the sheriff at least 4 months before the expiration of the period of redemption. If the purchaser or assignee delivers the notice and service list for an additional service attempt upon an entity or to a location that was not included on the service list for the first attempt to the sheriff at least 4 months before the expiration of the period of redemption, then the sheriff's failure to serve the notice in accordance with this Section may be grounds for a sale in error under Section 22-50 but not under subparagraph (5) of subsection (a) of Section 21-310. If the purchaser or assignee fails to deliver the notice and service list for an additional service attempt upon an entity or to a location that was not included on the first service list to the sheriff at least 4 months prior to the expiration of the period of redemption, then the sheriff's failure to serve that additional notice in accordance with this Section is not grounds for a sale in error under either Section 22-50 or subparagraph (5) of subsection (a) of Section 21-310.
In counties of 3,000,000 or more inhabitants where a taxing district is a petitioner for tax deed pursuant to Section 21-90, in lieu of service by the sheriff or coroner the notice may be served by a special process server appointed by the circuit court as provided in this Section. The taxing district may move prior to filing one or more petitions for tax deed for appointment of such a special process server. The court, upon being satisfied that the person named in the motion is at least 18 years of age and is capable of serving notice as required under this Code, shall enter an order appointing such person as a special process server for a period of one year. The appointment may be renewed for successive periods of one year each by motion and order, and a copy of the original and any subsequent order shall be filed in each tax deed case in which a notice is served by the appointed person. Delivery of the notice to and service of the notice by the special process server shall have the same force and effect as its delivery to and service by the sheriff or coroner.
The same form of notice shall also be served, in the manner set forth under Sections 2-203, 2-204, 2-205, 2-205.1, and 2-211 of the Code of Civil Procedure, upon all other owners and parties interested in the property, if upon diligent inquiry they can be found in the county, and upon the occupants of the property.
If the property sold has more than 4 dwellings or other rental units, and has a managing agent or party who collects rents, that person shall be deemed the occupant and shall be served with notice instead of the occupants of the individual units. If the property has no dwellings or rental units, but economic or recreational activities are carried on therein, the person directing such activities shall be deemed the occupant. Holders of rights of entry and possibilities of reverter shall not be deemed parties interested in the property.
When a party interested in the property is a trustee, notice served upon the trustee shall be deemed to have been served upon any beneficiary or note holder thereunder unless the holder of the note is disclosed of record.
When a judgment is a lien upon the property sold, the holder of the lien shall be served with notice if the name of the judgment debtor as shown in the transcript, certified copy or memorandum of judgment filed of record is identical, as to given name and surname, with the name of the party interested as it appears of record.
If any owner or party interested, upon diligent inquiry and effort, cannot be found or served with notice in the county as provided in this Section, and the person in actual occupancy and possession is tenant to, or in possession under the owners or the parties interested in the property, then service of notice upon the tenant, occupant or person in possession shall be deemed service upon the owners or parties interested.
If any owner or party interested, upon diligent inquiry and effort cannot be found or served with notice in the county, then the person making the service shall cause a copy of the notice to be sent by registered or certified mail, return receipt requested, to that party at his or her residence, if ascertainable.
The changes to this Section made by Public Act 95-477 apply only to matters in which a petition for tax deed is filed on or after June 1, 2008 (the effective date of Public Act 95-477).
35 ILCS 200/22-15