In the current audit markets, there is much attention given to the tax auditors' role in ensuring tax compliance as the tax audit is currently the IRBM's primary activity. This study using questionnaires to examine the relationship between core competencies towards their performance in completing audit cases. The increase in tax auditor's performance may reduce the number of unresolved audit cases and increase the voluntary compliance among the taxpayers. 231 questionnaires were completed and returned to be further analysed. It takes a competent tax auditor to resolve all the audit cases and reduce the issues of dissatisfaction among taxpayers on the attitude and performance of the tax auditors. It is the responsibility of the tax administrator to improve the efficiency of tax audits by enhancing the competency of tax auditors. The result in this study shows a positive relationship between skills and knowledge towards performance.