35 ILCS 200/15-20
If any property listed as exempt by the chief county assessment officer has a change in use, a change in leasehold estate, or a change in titleholder of record by purchase, grant, taking or transfer, it is the obligation of the transferee to notify the chief county assessment officer in writing within 90 days of the change. If mailed, the notice shall be sent by certified mail, return receipt requested, and shall include the name and address of the taxpayer, the legal description of the property, the address of the property, and the permanent index number of the property where such number exists. If notice is provided in person, it shall be provided on a form prescribed by the chief county assessment officer, and the chief county assessment officer shall provide a date stamped copy of the notice. Except as provided in item (6) of subsection (a) of Section 9-260, item (6) of Section 16-135, and item (6) of Section 16-140 of this Code, if the failure to give such notification results in the assessment officer listing the property as exempt in subsequent years, the property shall be considered omitted property for purposes of this Code.
35 ILCS 200/15-20