In an on-line method of analyzing financial accounting data, uploaded financial accounting data is received at a server (2) from a client computer (3). The data is analyzed at the server (2) to identify anomalies in the data. A display is provided at the client computer (3) representing the anomalies that have been identified. Further, in a method of pre-processing financial accounting data prior to analyzis of the data, the financial accounting data is abstracted to correspond to a pre-stored accounting ontology. Further, in a method of analyzing financial accounting data, the method checks the data for violation of a particular state to identify inconsistent combinations of values in the data.