You (or the purchaser or transferee) must complete Form CBS-1, Notice of Sale, Purchase, or Transfer of Business Assets. Stepbystep guide on how to write contracts for leases, business partnerships, and employment contracts.This contract is a legally binding document outlining the terms and conditions for the sale of a business and its assets. A buysell agreement is a legally binding contract that sets out the terms of how business partners will manage their ownership if one of them leaves. To sell a business in Illinois, you'll need various legal documents, including a bill of sale, asset purchase agreement, and non-disclosure agreements. Form CBS-1 must be filed with IDOR at least ten (10) business days prior to the date of sale or transfer. A business purchase agreement is a legal contract specifying terms for buying or selling a business, including conditions and obligations. Illinois Business Purchase Agreement Template. Utilize our no-cost Business Purchase Agreement to document the sale of a business.