Irregular employment is a multifaceted phenomenon, which spans from totally undeclared work (paid lawful activities not declared to public authorities) to activities involving organized networks that engage in illicit economic activities (eg smuggling of goods, drug trafficking, or other criminal activities). Under certain circumstances, the presence of irregular work may be widely accepted and not even be perceived by citizens as outside of the law properly speaking, especially in countries where the informal economy is a sizeable phenomenon (Williams et al. 2017). However, irregular employment that involves foreign workers is a target of significant national and international political debate leading to policy actions in the fields of immigration and labour market regulations in most of European countries for over 20 years now (OECD 2000). The connection between undeclared work and irregular migration often combines in an explosive mix that stirs anxieties about state’s control over migration flows, labour market regulation, unfair competition with native workers, and lost revenues for the state. Although rough and volatile, estimates on the size of irregular migration in Europe point to a quite limited phenomenon involving between 1.9 and 3.8 million people in 2008 (Kovacheva and Vogel 2009). However, according to most analysts