The characteristics of accounting information systems (AISs) within organizations and the factors affecting their effectiveness are investigated in this study. In particular, how external consultants moderate the relationship between the determinants and AIS effectiveness is examined. A total of 167 agricultural companies in the Ben Tre Province of Vietnam were surveyed using a regression-based partial least squares structural equation model. Then, the influence of these determinants on AIS effectiveness was evaluated. The findings showed that managers' involvement and managers' accounting knowledge positively affect AIS effectiveness. Furthermore, the involvement and knowledge of managers are mitigated by external consultants, which reduces the negative influence of such involvement on AIS effectiveness. This study aims to contribute to the body of knowledge on the determinants affecting AIS effectiveness by providing agricultural companies in Ben Tre and Vietnam with insights into the effectiveness of their respective AIS activities.