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. You (or the purchaser or transferee) must complete Form CBS-1, Notice of Sale, Purchase, or Transfer of Business Assets.Discusses all of the key documents you need to buy or sell a business, including the principal transaction agreement and common ancillary documents. These forms are also available in the DotLoop and DocuSign form libraries. A business purchase agreement is a legal contract specifying terms for buying or selling a business, including conditions and obligations. The easiest way to create a Business Purchase Agreement is to use a template that is customized to your state. Free Consultation - Call (312) 889-8702 - The Castle Law Firm helps companies with business matters in Business and Franchise Law cases.