35 ILCS 200/31-30
The recorder or registrar of titles shall not record the declaration, but shall insert on the declaration and all attachments the Document Number assigned to the deed or trust document, and shall within 30 days of receipt transmit the declaration to the chief county assessment officer. The chief county assessment officer shall insert on the declaration the most recent assessed value for each parcel of the transferred property and other information required by the Department, and, within 30 days of receipt or within 30 days of the adjournment of the board of review for the previous assessment year, whichever is later, shall transmit all the declarations to the Department. The chief county assessment officer may also copy and retain any information relating to the property transferred to assist in determining the proper assessed valuation of the property transferred and other properties in his county.
35 ILCS 200/31-30