This paper investigates informality driven by the intense use of temporary and part- time contracts by firms. In the first part, using administrative data released by the Italian Social Security Institute combined with data of firms’ financial statements, I construct an indicator of irregular job implementing LASSO technique. Irregu- lar temporary and part-time contracts are highly correlated with known measures of undeclared work provided, with a stronger incidence in Southern Regions, in Services and Commerce and of female part-time workers. In the second part, I investigate if irregular contracts are effectively used to hide work that otherwise would be completely undeclared. First, I show with an event study analysis that lower EPL induce firms to fire irregular workers more easily, part-time contracts in sectors of Services and Commerce. Second, I investigate how less financial devel- opment positively impact the number of irregular part-time workers, especially if they are female workers again in Services and Commerce. JEL Classification Numbers: H26, H29.