This study aims to demonstrate the role of (TSA) in reducing the deficit in the federal budget in Iraq by controlling budget estimates. To achieve this research, the researchers raised a set of questions represented in a checklist that searches for the role of (TSA) in controlling federal budget estimates in Iraq from the point of view of the administration responsible for preparing the general budget in the Ministry of Finance. One of the most important results reached by the researchers is that there is a role for (TSA) in controlling federal budget estimates by controlling revenues and expenditures and improving cash management. This gives a more realistic picture of the government's cash position, which reduces the need for unnecessary borrowing and reduces idle funds, which leads to reducing the deficit. The most prominent recommendations are the necessity of applying (TSA) in the Ministry of Finance because it provides a comprehensive view of the revenues and expenditures of government units at the end of each day, which contributes to controlling budget estimates and reducing the budget deficit.