The main objective of this study was to investigate the factors which influence effectiveness of tax audit in Somali Regional State Revenue Authority. To achieve the objective, we have used quantitative approach and explanatory & descriptive research designs to investigate the effects of the factors on the effectiveness of tax audit under the study. The data collection instrument was structured close ended survey questionnaires using the five point Likert scale adopted from different scholars in previous studies. The sample size was 64 respondents and all population members were included and 64 questionnaires were filled and returned. To achieve the objectives of the study, the researcher used multiple regression analysis using SPSS software. The result of this finding indicated that management support, information system, and resource availability had a positively significant contribution while tax audit independence was found to be insignificant effect on the effectiveness of tax audit in Somali Regional State Revenue Authority. It is recommended that leaders under study ought to combine and use the resources wisely.