Despite the introduction of online tax filing platforms in Nigeria, taxpayer compliance rates remain suboptimal with significant variations in platform usage and effectiveness. This study examined the effect of online tax filing platforms on taxpayer compliance, specifically assessing the effects of platform accessibility, user experience quality, and technical capabilities on compliance behavior. The study employed a quantitative cross-sectional survey design with 578 registered taxpayers selected through multi-stage sampling across Nigeria's six geopolitical zones. Data were collected using a structured questionnaire and analyzed using Partial Least Squares Structural Equation Modeling (PLS-SEM). Results revealed that all three platform characteristics significantly and positively influenced taxpayer compliance. The combined model explained 54.2% of variance in taxpayer compliance. To enhance compliance, the study recommends: (1) Revenue agencies partnering with telecom providers to improve connectivity and develop offline filing options for better accessibility; (2) Tax authorities redesigning interfaces for intuitiveness and reliability, coupled with expanded support services, to elevate user experience; and (3) Government investing in cybersecurity, mobile optimization, and system integrations to strengthen technical capabilities and foster taxpayer trust