What is needed for a Contract for Deed? What can you expect when closing a real estate deal in Illinois?Keep reading for answers to the 10 most common questions Illinois buyers and sellers have. Under Illinois law, the purchase or sale of real estate requires a written document or contract to be enforceable. An Illinois real estate contract is a legally binding document that outlines the terms and conditions of a real estate transaction between a buyer and a seller. Most mortgage contracts contain a clause that requires the lender to send a "breach letter" when the loan defaults. An Illinois real estate contract is a legally binding document that outlines the terms and conditions of a real estate transaction between a buyer and a seller. In the Multiboard 7.0 Contract, Section 15 lists the 22.1 disclosure warranties the seller gives in Illinois. A purchase agreement is a legal document containing important terms and conditions of your real estate transaction.