This contract is a legally binding document outlining the terms and conditions for the sale of a business and its assets. Free Consultation - Call (312) 889-8702 - The Castle Law Firm helps companies with business matters in Business and Franchise Law cases.You (or the purchaser or transferee) must complete Form CBS-1, Notice of Sale, Purchase, or Transfer of Business Assets. A business purchase agreement should detail the names of the buyer and seller at the start of the contract. To sell a business in Illinois, you'll need various legal documents, including a bill of sale, asset purchase agreement, and non-disclosure agreements.