This research has goaled primarily to focus on the role and importance of the tax revenues as one of the most important terms in the economy, which is affected by financial sustainability indicators, particularly (investment spending and economic growth). The financial sustainability indicators effect on the tax revenues, whether by increasing or decreasing them. The investment spending varies from one country to another and from one economy to another, depending on the size of spending and the state's ability to direct that spending to create productive capacities that contribute to expanding the tax base. This is in addition to the important role played by economic growth as a catalyst for expanding the tax base. Therefore, the research methodology relies on the use of the inductive approach to analyze general and theoretical aspects, as well as the deductive approach to analyze statistics and data, using the quantitative measurement method to analyze and measure the impact of investment spending and economic growth on tax revenues in Iraq for the period (2004-2023). The study issue lies in determining in presence or for lack of a statistically significant, positive or negative, impact stemming from financial sustainability indicators, represented by (investment spending and economic welfare ). Tax Revenues in our country .The research has found a statistically significant positive effect of financial sustainability indicators (investment spending and economic growth) on tax revenues in Iraq for the period (2004-2023) in the short term. The study also found a significant negative effect in the long term. Consequently, the study recommends developing the tourism sector, providing support to manufacturing industries, digitizing the tax system, and improving collection mechanisms to increase tax revenues and prevent tax evasion.