Introduction. Detection of errors, assumption of fraud facts, proof of distorted information and hidden true facts are among the objects of the auditor's research in the process of audit activity. Problem Statement. To date, the structure of fraud, classification, types of errors, and their dynamics have not been fully investigated; there is no clear structuring of the causes of fraud and errors; the trend of their change has not been fully analyzed. Purpose. To improve the categorical apparatus; to investigate and analyze the causes of their occurrence, possible consequences; conduct an analysis of the general trend of changes in the number of proven fraud facts by judicial authorities. Materials and Methods. In the research process, the following were used: actual data from audits; results of the National Development and Reform Commission of the Department of Accounting and Taxation of KKIBP. Methods used: generalization, systematization, comparison, critical analysis, grouping, evaluation, trend analysis. Results. The results of research on the nature of fraud and error are highlighted. The analysis of their structure, causes and possible consequences was conducted. Improved categorical apparatus: “fraud”, “error”. Analyzed trend changes fraud. Formed groups fraud . The results of research into the nature of the occurrence of fraud and errors are highlighted. An analysis of their structure, causes and possible consequences was carried out. The categorical apparatus of the concepts "fraud", "error" has been improved. The trend of changing fraud was analyzed. His groups have been formed. Conclusion. The grouping of fraud proposed by the authors will make it possible to identify new criteria for distinguishing (detecting) and classifying fraud, thereby improving management decision-making, which will provide a greater probability of knowing the object, and the identified causes of fraud during the audit will determine the selection of criteria for its classification. Based on the actual data of the State Statistical Service of Ukraine, the trend of decreasing the number of fraud cases has been proven. The classification of fraud and errors has, first of all, scientifically based and practical significance, which allows to build a clear system of knowledge about the latter as an object of research and to form the correct system of their detection and management.