In a number of scenarios, medium-sized and small companies are seen as driving forces of the economy. Nevertheless, it is often seen that their lifespan is really short, since they cannot respond to market demands, and thus they end up closing. This is due to the lack of compe-titive internal and external business practices, as well as of spaces for identifying and working on needs, and of oppor-tunities for developing themselves as long-term organiza-tions. The increasing need for information, as well as the need to grow, gain strength and stay in the market, leads to the identification of a number of needs in small and me-dium-sized companies. Such needs have been classified on the basis of their relationship to the environment, the ma-king of decisions, as well as the company’s internal struc-ture and processes. These aspects are directly related to the objectives of the business information system, which is understood as the set of human, physical and informational resources that interact in order to support the activities and the management of a company. This article proposes that these needs can be met if the business information system is modified in order to respond to demands related to infor-mation gathering, management and production within the organization. This will facilitate prompt and timely deci-sion-making, and will positively influence both the running and the sustainability of small and medium-sized compa-nies. Nevertheless, the business information system is a so-lid system which consists of a number of subsystems. This study is focused on the accounting information subsystem, which is composed of financial accounting, management accounting, finances, auditing, control and transparency practices. The accounting information subsystem provides the business information system with valuable input and support, based on the best international practices. These are internationally recognized methodologies that promote the presentation of useful information to the company, and are geared toward optimizing decision making, as well as the achievement of strategic objectives. This allows small and medium-sized companies to mitigate, satisfy and res-pond to their information needs by developing significant improvements that create opportunities and enhance their sustainability and competitiveness.