The primary aim of the research work was to examine the effect of job stress on employees’ performance in an organization. In order to achieve this aim, the Federal Inland Revenue Service Utako MS and IE tax office branch Abuja was chosen as a case study. This research work involves the administration of the questionnaire to obtain data for the study and a random sampling procedure was used in the selection of respondents from the organization (FIRS) under study. The Chi-square statistical test was used in analyzing the data obtained. Based on the analysis above, the research finds that job stress posts a great deal of effect to employee performances and discovered that as a result of stress, there are some dangerous health issues that employees are faced with ranging from both physical and emotional. Therefore, the researcher recommends that revenue/financial generating organizations such as the FIRS, should embark on resizing/reducing employee workload to a more manageable size so as to allow them (employee) put in their best for maximum productivity and finally a conducive working environment should be made available to employee which will aid and serve as a morale booster.