You (or the purchaser or transferee) must complete Form CBS-1, Notice of Sale, Purchase, or Transfer of Business Assets. You are required to report all sales of businesses to the Illinois Department of Revenue.Disclosure of this information is REQUIRED. In an asset sale, the new owner purchases the business's physical assets. The seller retains all rights to the legal entity. To sell a business in Illinois, you'll need various legal documents, including a bill of sale, asset purchase agreement, and non-disclosure agreements. The seller should be ready to provide detailed information about the business's assets, liabilities, revenues, costs, and customer base, among other things. Use Form 4797 to report: The sale or exchange of property. The involuntary conversion of property and capital assets.