First Author:   Enlinson Mattos Fundacao Getulio Vargas - Sao Paulo School of Economics enlinson.mattos@fgv.br   Rua Dr. Plinio Barreto, 365 São Paulo, 01313020, Brasil   1137993597(Phone) 1137993597(Fax) Second Author: Leonardo Stelzer-Rossi Tax Revenue Service - Sao Paulo leostelzer@hotmail.com