Before you buy an existing business, find out if the business owes any Texas taxes. Drafting a purchase agreement for buying or selling a business in Texas is a critical step to ensure a smooth transaction.This article discusses the elements of buying or selling a small business in Texas, whether the business is focused on real estate or otherwise. Before an offering or sale of a business opportunity in. Texas, the principal seller must register the business opportunity with the secretary of state. Tex. Legal considerations when buying or selling a business in Texas. In the realm of Texas business transactions, legal factors are paramount. Want to start a business but now sure what the first step is? Read our Starting a Business FAQs then get in touch with an SBDC Business Advisor today! A business sale agreement is a legal document that describes and records the price and other details when a business owner sells the business.