The objective of this article is to analyse through the empirical strategy of differences in differences, applied to panel data, the impact of the Fiscal Responsibility Law - disaggregated in three categories - on the size of the government and on the productivity of the expenditures of Ceará municipalities between 2002 2016. Among the results, it was found that municipalities that comply with the limit set by the LRF for payment of salaries, tend to have a reduction in the size of the government. In addition, those who meet both the payroll and public spending limits are more likely to experience an increase in the productivity of their spending. In this sense, given the effectiveness of the Fiscal Responsibility Law, stricter control measures are recommended in the effectiveness of this Law, especially in electoral periods.