We investigate whether firms have incentives to retain their status as small and medium enterprises (SMEs) to benefit from various SME policies. To examine this issue, we use the exogenous changes in the SME Basic Act in Japan. The SME Basic Act describes aims of SME policies in Japan, which involve enhancing the growth of SMEs using policy. The Act also contains the requirements and definitions of SMEs that are the target of the policies. Only firms that satisfy the definitions of SMEs under the SME Basic Act can participate in the SME policy programs in Japan. The requirements regarding capital stock in the SME Basic Act were changed in 1999. By focusing on the change in the requirements for capital stock as an exogenous event, we show that firms are less likely to increase their capital stock so that they can continue to satisfy the requirements that retain their status as SMEs. Furthermore, firms that increase their capital stock increase their size. As firms have a disincentive to increase capital stock so that they can keep their SME status, this indicates that the SME requirements are significant constraints on firm growth. Many studies show that individual SME policies (such as R&D subsidies and public credit guarantees) stimulate firm growth and activities that are consistent with the aim of these SME policies. Although the purpose of the SME Basic Act is the enhancement of the growth of SMEs, we show that the requirements under this law impede the growth of SMEs.