EN
Income, beside expenses, is the main accounting category that determines the performance of an entity. The article tackles two main questions related to repre-sentation in accounting of this economic category – definition of the moment when income is earned and its adequate measurement.The author presents the definition of income in accounting theory and analyzes Polish accounting regulations on this matter by comparing them with Internation-al Accounting Standards.The main differences between these two sets of regulations are identified and the need to develop clear and consistent rules regarding the recognition of income and its measurement is emphasized.