Um modelo econométrico com parâmetros variáveis para a carga tributária bruta brasileira trimestral

This article presents a linear econometric model with variable coefficients for the analysis of the quarterly dynamics of the Brazilian gross tax burden in the 1995-2008 years.The choice of this particular model was motivated by the constant changes made in the Brazilian tax system during these years - most frequently in the scope, design, and size of pre-existing taxes, but once in a while also the elimination of some of these taxes and/or the creation of new ones. The main conclusions of the paper are that: (i) GDP is, quite certainly, the main explanatory variable of the dynamics of the quarterly tax burden during the period in question; (ii) the share of the quarterly Brazilian tax burden that does not depend on GDP (or on any other variable, for that matter) increased quite significantly during the latter period - possibly due to continuous improvements on the ability of the Brazilian government to raise tax revenues and/or increases in the size of the economy's formal sector; and (iii) the GDP-elasticity of the Brazilian tax burden appears to have fluctuated around values well below unity, contrarily to what estimates based on models with constant coefficients would lead us to believe.