This study aims to analyze the effects of tax knowledge and taxpayer awareness on motor vehicle taxpayer compliance, with service quality serving as a moderating variable at SAMSAT Balikpapan City Region. Based on the Theory of Planned Behavior, this study examines how internal and external factors influence taxpayers’ intentions to comply with tax obligations. A quantitative research approach was employed using primary data collected through questionnaires distributed to 124 motor vehicle taxpayers. The data were analyzed using Variance-based Structural Equation Modeling (SEM) with SmartPLS 4 software to examine both direct and moderating relationships among the variables. The findings reveal that tax knowledge does not have a significant effect on motor vehicle taxpayer compliance. In contrast, taxpayer awareness has a positive and significant effect on taxpayer compliance, indicating that a higher level of awareness encourages greater compliance with tax obligations. Furthermore, service quality successfully moderates and strengthens the relationship between tax knowledge and taxpayer compliance, suggesting that high-quality public services can enhance the effectiveness of taxpayers’ knowledge in promoting compliance. However, service quality does not moderate the relationship between taxpayer awareness and taxpayer compliance, implying that awareness independently influences compliance regardless of the quality of services received. This study concludes that improving taxpayer awareness and maintaining high-quality public services are essential strategies for increasing motor vehicle taxpayer compliance and supporting more effective tax administration.