In order to achieve higher data quality targets, organizations need to identify the data quality dimensions that are affected by poor quality, assess them, and evaluate which improvement techniques are suitable to apply. Data quality literature provides methodologies that support complete data quality management by providing guidelines that organizations should contextualize and apply to their scenario. Only a few methodologies use the cost-benefit analysis as a tool to evaluate the feasibility of a data quality improvement project. In this paper, we present an ontological description of the cost-benefit analysis including the most important contributes already proposed in literature. The use of ontologies allows the knowledge improvement by means of the identification of the interdependencies between costs and benefits and enables different complex evaluations. The feasibility and usefulness of the proposed ontology-based tool has been tested by means of a real case study.