(735 ILCS 5/9-104.1) (from Ch. 110, par. 9-104.1)
    Sec. 9-104.1. Demand; notice; return; condominium and contract purchasers.
    (a) In case there is a contract for the purchase of such lands or tenements or in case of condominium property, the demand shall give the purchaser under such contract, or to the condominium unit owner, as the case may be, at least 30 days to satisfy the terms of the demand before an action is filed. In case of a condominium unit, the demand shall set forth the amount claimed which must be paid within the time prescribed in the demand and the time period or periods when the amounts were originally due, unless the demand is for compliance with Section 18(n) of the Condominium Property Act, in which case the demand shall set forth the nature of the lease and memorandum of lease or the leasing requirement not satisfied. The amount claimed shall include regular or special assessments, late charges or interest for delinquent assessments, and attorneys' fees claimed for services incurred prior to the demand. Attorneys' fees claimed by condominium associations in the demand shall be subject to review by the courts in any eviction proceeding under subsection (b) of Section 9-111 of this Act. The demand shall be signed by the person claiming such possession, his or her agent, or attorney.
    (b) In the case of a condominium unit, the demand is not invalidated by partial payment of amounts due if the payments do not, at the end of the notice period, total the amounts demanded in the notice for common expenses, unpaid fines, interest, late charges, reasonable attorney fees incurred prior to the initiation of any court action and costs of collection. The person claiming possession, or his or her agent or attorney, may, however, agree in writing to withdraw the demand in exchange for receiving partial payment. To prevent invalidation, the notice must prominently state:
    "Only FULL PAYMENT of all amounts demanded in this notice will invalidate the demand, unless the person claiming possession, or his or her agent or attorney, agrees in writing to withdraw the demand in exchange for receiving partial payment."
    (c) The demand set forth in subsection (a) of this Section shall be served either personally upon such purchaser or condominium unit owner or by sending the demand thereof by registered or certified mail with return receipt requested to the last known address of such purchaser or condominium unit owner or in case no one is in the actual possession of the premises, then by posting the same on the premises. When such demand is made by an officer authorized to serve process, his or her return is prima facie evidence of the facts therein stated and if such demand is made by any person not an officer, the return may be sworn to by the person serving the same, and is then prima facie evidence of the facts therein stated. To be effective service under this Section, a demand sent by certified or registered mail to the last known address need not be received by the purchaser or condominium unit owner. No other demand shall be required as a prerequisite to filing an action under paragraph (7) of subsection (a) of Section 9-102 of this Act. Service of the demand by registered or certified mail shall be deemed effective upon deposit in the United States mail with proper postage prepaid and addressed as provided in this subsection.
(Source: P.A. 100-173, eff. 1-1-18.)