This study aims to analyze the authority of the Supreme Audit Agency (BPK) in determining state financial losses due to corruption and the legal implications of calculations by institutions other than the BPK. The method used is normative legal research with a statutory, conceptual, and case-based approach. The results show that the BPK has attributive constitutional authority in determining state financial losses, which cannot be replaced by other institutions. The results of the BPK audit have binding legal force and serve as important evidence in proving corruption. Meanwhile, the results of audits by other institutions are administrative in nature and do not have the same evidentiary force. The legal implication is the importance of legal certainty and clarity of authority in the process of enforcing the law on corruption.