The Directorate General of Taxation has established an online repository called Tax Knowledge Base or TKB. TKB has been widely recognized and used by tax authorities, albeit not maximally. This study used a quantitative descriptive method to analyse constructs of the Unified Theory of Acceptance and Use of Technology to specifically figure out TKB use at KPP Madya South Jakarta I with a sample size of 88. A significant effect was demonstrated by Performance Expectancy on Behavioural Intention, Facilitating Condition and Behavioural Intention to Use Behaviour. Insignificance was apparent in the effect of Effort Expectancy and Social Influence on Use Behaviour. This study recommends that the Directorate General of Taxation should require tax authorities to use TKB on a daily basis.