This paper examines how workforce composition, labor demand, and minimum wage jointly determine wages through their effects on worker-task assignments, firm wage premiums, and firm-worker sorting. Using an estimated model of monopsonistic local labor markets, it finds that minimum wage hikes and labor demand shocks drove the decline in Brazilian wage inequality from 1998 to 2012. While rising educational attainment compressed skill premiums within firms, it also reallocated skilled workers to high-wage firms, limiting that shock’s effect on inequality. The analysis highlights interactions among exogenous factors, showing that concurrent supply and demand changes attenuated minimum wage impacts. (JEL J22, J23, J24, J31, J38, J42, R23)

Abstract We develop a search model of informal labour markets with realistic labour regulations, including minimum wage, and heterogeneous workers and firms. Smaller firms and lower wages in the informal sector emerge endogenously as firms and workers decide whether to comply with regulations. Because skilled and unskilled workers are imperfect substitutes in production, the model uniquely captures the informality consequences of shocks that affect returns to skill, such as rising educational levels. The model also reproduces empirical patterns incompatible with other frameworks: the presence of skilled and unskilled workers in the formal and informal sectors, the rising share of skilled workers by firm size, and formal and firm-size wage premiums that vary by skill level. We estimate the model using 2003 data from Brazil and show that it successfully predicts labour market changes observed between 2003 and 2012. Under a range of different assumptions, changes in workforce composition appear as the main drivers of the reduction in informality over this period. Policy simulations using the estimated model suggest that progressive payroll taxes are a cost-effective way to reduce informality.