The document provides an overview of audits conducted by the European Research Council Executive Agency (ERCEA) on costs reported under the Framework Programme 7 (FP7). It discusses the common goal of audits to ensure costs are legal and regular, and to maintain an error rate below 2%. Systematic and non-systematic errors are examined, as well as how systematic errors may be extrapolated across other grants. Common errors found in personnel costs, other direct costs, and accounting practices are summarized. Recent examples of errors identified in top beneficiaries are also provided.