Selling expenses definition including break down of areas in the definition. Analyzing the definition of key term often provides more insight about concepts. Selling expenses can be defined as: Expenses of promoting sales, such as displaying and advertising merchandise, making sales, and delivering goods to customers. Selling expenses are expenses related to making sales and is usually broken out into a separate category on a multi-step income statement. Showing the sales expenses in a separate section allows a reader more detail, detail that can be used to compare sales expenses to total sales providing a ratio of sales expenses to sales.