Operating revenue is income generated by the core activities of a business, such as sales of goods or services. Non-operating revenue is income not related to the day-to-day operations of the business and includes items such as interest income and gains on investments. The difference between operating and non-operating revenue is important for both tax purposes and in understanding the total financial picture of a business. Operating revenues are subject to most taxes, while non-operating revenue may be excluded from taxable income in certain circumstances. Knowing exactly what your business earns in each category can help you manage and optimize your financial performance.