Since the 1970s, the importance of small business - SB - has increasingly been recognized in the world and in Brazil. Among the measures taken by the Brazilian government to encourage and promote SB, the National Simplified Taxation System - NSTS - stands out.§ There are, however, many companies that meet the requirements to be in the NSTS, but they do not opt for this system. The objective of this study is to identify and analyze the reasons for this decision. This is an exploratory qualitative investigation based on a case study. The results show that the NSTS simply does not work for companies whose customers are large retail companies. Thus, the study concludes that, for certain sectors, SBs face a drawback: SBs can no longer pay federal taxes in a unified way.