Abstract 

The study aimed to identify the impact of the internal control system on income tax departments and their revenues. A purposive sample was employed. The sample consisted of (46) employees from the regional offices in the governorates of Nablus, Tulkarem and Jenin. Descriptive approach has been implemented in order to achieve the objectives of the study. In addition, a questionnaire was developed to fit the purpose study.  The results indicated that there was high impact of the control environment variables, control activities, and control on income tax revenues. This comes in terms of the overall arithmetic mean of 4.07 and the overall standard deviation of 0.80 .The study recommended that the Ministry of Finance should pay more attention to the internal control system in the income tax departments through meetings with the directors of the regional income tax offices, thus to enable them to identify, and discuss their practical problems, to come up with suggestion for appropriate remedies and solutions. Moreover, the Ministry of Finance and the General Administration of Income Tax need to apply more improvements and developments on the influential factors that affect the regulatory environment of control.