Tax Parameters in the Portuguese Economy - Part I : Indirect Taxes

In the first of two twin papers, we focus on indirect taxes and formally discuss the correspondences between statutory and effective tax rates in the Portuguese economy. These correspondences depend on the details of the Portuguese tax law, on a wealth of data information, and on certain priors about the values of behavioural parameters in the economy. For each of the different tax margins, we choose a specification of the tax base that is standard in tax policy evaluation exercises, albeit necessarily only an approximation to the true tax base. In addition to the general correspondences, we present our own estimates of the effective tax rates at the different tax margins. More importantly, however, using the information in this paper, practitioners of tax policy evaluation can obtain their own estimates of the relevant tax parameters