The study aimed to examine the complementary relationship between INTOSAI standards and IT governance oversight, and to identify the impact of this relationship on rationalizing public spending. This was achieved by identifying the level of application of INTOSAI standards related to information technology, the level of application of IT governance, and the extent of their reflection on rationalizing government spending. The study adopted the descriptive analytical approach, and the study population consisted of specialists in the field of oversight from academia and professionals working at the Libyan Audit Bureau. The study sample consisted of (30) individuals, and the questionnaire was used as a tool for data collection. The data were analyzed using the SPSS statistical analysis program. The results of the study showed that the level of application of INTOSAI standards related to information technology was low, as was the level of application of IT governance. The results also showed a low level of rationalizing government spending. The results also revealed a statistically significant positive correlation between INTOSAI standards and IT governance oversight, which confirms the existence of a complementary relationship between them, contributing to explaining part of the change in rationalizing public spending..................... Keywords:.... INTOSAI standards, IT governance, rationalizing government spending, oversight, Libyan Audit Bureau.