Resumo: This study summarizes the results of a research project that seeks to ascertain the reasons for which small firms have not adopted the Portuguese simplified income tax system for micro businesses. Data were collected through a survey questionnaire, along with 242 small firms who met the conditions to be framed under the simplified tax (RST). Results indicate that i) the choice of the income tax system was made based on the criterion of tax saving, ii) the main factor in the rejection of the simplified system was the existence of unadjusted national technical coefficients iii) most micro-enterprises are open to the option for a simplified system with features of tax / minimum collection, and iv) accountant played a key role in the choice of tax system v) accounting in many companies is perceived as an instrument for compliance with tax and legal obligations
