The process is comprised of four general steps: conversation, letter of intent, definitive documentation and closing. When buying the assets of a business, some are subject to sales or use tax, while others are not.Items subject to retail sales tax. How do I create a Business Purchase Agreement? Here's a step-by-step on creating a business purchase agreement with a free business purchase agreement template. A business sale agreement is a legal document that describes and records the price and other details when a business owner sells the business. A purchase and sale agreement is a contract between you and someone else. Such a contract involves one party buying and another party selling something.