A Research Report Submitted to Mzumbe University – Mbeya Campus College in Partial Fulfillment of the Requirement for the Award of the Bachelor Degree of Accounting and Finance (BAF-BS) of Mzumbe University.The research aimed at assessing the effects of internal controls on revenue collection in Tanzania, with a specific case of the TRA Kimara Branch Dar es salaam. The study was guided by the three objectives: to find out on how separation of duties impact the process of revenue collection in Tanzania Revenue Authority , to identify the essence of effective supervision towards revenue collection in TRA, lastly the study determine job rotation, and its impact on revenue collection in TRA. The research hypothesis was then developed from the research objectives. The theoretical background of internal control was analyzed to identify its relevance to the study. The study employs case study research design. Also the study had a sample size of 40 respondents in different department at TRA Kimara Branch. This study involves research instruments such as questionnaires for data collection. The conceptual framework was illustrated and the research variables discussed in depth. The empirical review of internal controls was analyzed to identify research gaps which this study sought to fill. The incidence of internal control weaknesses, unsatisfactory and deteriorating service delivery have the undesired effect of not only weakening the organization ability to effectively collect revenue but also encourages collusion, fraud, embezzlements, loss of cash (revenue), assets conversion genuine and deliberate mistakes, corruption, lack of transparency and accountability for revenue collection and other assets. Despite considerable investment, service delivery is unsatisfactory and degenerating. For the enhancement of the attainment of the mission and goals of the organization, it is therefore necessary that these hindrances be removed. The management of the organization should familiarize themselves with internal control procedures that will ensure effective service delivery and the desired revenue generation. Thus, the purpose of this study is to examine and evaluate the internal control system in operation at Tanzania Revenue Authority with a view of knowing whether strengthening of internal controls can have any effect of revenue collection. On the recommendation the research has achieved a considerable ground with regard to TRA Dar es salaam and their systems of control which has opened up the organization for further research work. Future study should link TRA to level of compliance by taxpayers to ascertain how the two relate in respect to each other. The study should also be done with comparison to other revenue bodies to recommend for other revenue collection measures. A replication of this study should be done after some time to find out if there are any changes that might have taken place as a result of time difference and then comparisons to be made with the current data, so that viable recommendations can be drawn. It is further recommended that the top management hierarchy to be reviewed to curb duplication of duties which has been evidenced by the study.