A Dissertation Submitted to MUDCC in Partial Fulfillment of the Requirements for the Award of the Degree of Master of Science in Human Resource Management (MSc-HRM) of Mzumbe University.A study on Assessment of the Effectiveness of Staff Utilisation was done at Tanzania Revenue Authority and the general objective was to investigate the effective and efficient use of staff and provide the actual situation of utilisation levels based on time, job challenges, working environment, skills and competencies. Along side this, the study specifically intended to determine the actual time spent by staff working on core business activities, determine the level of utilization of the available workforce in order to know whether their work challenges are proportional to their skills and competencies, assess the usage of technology in improving staff service delivery to stakeholders and to assess whether work environment affects staff utilization. Both theoretical and empirical literature was reviewed. The study was based on the Flow Theory framework and Person – Environmental Fit Theory to ascertain whether TRA operational employees are optimally utilized. It employed case study design that covered the population of all 700 Dar es Salaam Domestic Revenue Tax Regions population by selecting a sample of 250 employees as units of inquiry. The study assessed the utilization of available workforce proportionate to skills and competencies, established the actual time spent by staff working on core business activities, assessed the usage of technology in improving staff service delivery to stakeholders and assessed whether the work environment affects staff utilization. The study revealed that, operational staffs under the Domestic Revenue Department in Dar es Salaam are generally not utilized at optimal level. The findings from the analysis indicate that 47.2% of the staff are overstretched, while 43.5% are fully utilized and 9.3% are underutilized. This means that overall, 56.5% of staff are not optimally utilized. The main reason for under utilisation is lack of flow in operations complimented with shortage of staff; systems downtime; inadequate working tools and poor working environments. In order to address the anomalies the study recommends the following for policy implications: Conducting Workload analysis as an on-going activity, redeployment of staff who are out of flow to areas where their competency can better be utilized, improve working environment, establish induction programs and formalized coaching and mentoring programs and introduce motivational schemes that shall enhance staff morale. In order for the organisation to utilise its staff effectively there must be a match between a job, skills and qualification which results to balanced work flow and person fit.