The formula involves ascertaining your former partner's equity stake, assessing the business worth, and determining the buyout sum. What should be included in a buyout agreement?In this guide, we will explain what buying out a business partner means, how to prepare to buy out a business partner, and more. You may use the conventional partnership buyout calculation to estimate the value of your partner's share in the business. General information. Purpose of Form IT-204. A buyout agreement lets you plan what'll happen when a partner leaves the business.