Fraud detection in public revenue in collaboration with the Independent Authority for Public Revenue (IAPR) in Greece. The public revenue lost due to tax fraud and evasion are huge, currently estimated up to 1€ trillion by the European commision, with enormous implications for the European countries and their citizens. Tax fraud and evasion presents a significant threat to society’s welfare since it harms seriously the capacity of countries to raise money and has a dramatic effect in economic and social policies; a slower economy with cuts in important public services such as education and healthcare systems. To perform efficiently fraud detection we will develop quantitative methods for dealing with population–scale and heterogeneous data by combining tools from network science, Bayesian statistics and machine learning. The research project is implemented in the framework of H.F.R.I call “Basic research Financing (Horizontal support of all Sciences) under the National Recovery and Resilience Plan “Greece 2.0” funded by the European Union – NextGenerationEU (H.F.R.I. Project Number: 15973).