Indonesian agriculture sector has a major contribution in the nation’s economy. However, due to decrease in supply chain performance, the overall performance is declining which affect negatively on Gross Domestic Product (GDP). The contribution of Indonesian agriculture sector in GDP is declined to 84110 IDR Billion in the second quarter of 2018 from 84577.50 IDR Billion in the first quarter of 2018. The supply chain is one of the responsible factors of this issue. Therefore, to address this problem, the objective of the current study is to investigate the role of cost accounting system (CAS) on supply chain operations by considering the internal and external contingent factors. Moreover, the moderating role of legal obligations was also examined. In rare cases, some studies formally documented the effect of CAS on supply chain operations. Managerial employees of agricultural firms were selected to collect the necessary data and 150 questionnaires were distributed among them. Results of PLS-SEM show that CAS had a significant positive contribution in supply chain operations. Better implementation of CAS in agriculture firms had the ability to boost the performance. Moreover, other factors such as firm size, product diversity and competition also had a significant effect on CAS implementation. In this survey, legal obligations moderated the relationship between firm size and CAS. Finally, this study is beneficial for agriculture firms to enhance their performance by using better supply chain strategies through CAS.