Behavioral Research to Track Unpaid Motor Vehicle Taxes in Kalasin Provincial Administrative Organizations

This study aims to examine the development of motor vehicle tax and fee collection through the lens of behavioural science. Focusing on the case of the Kalasin Provincial Administrative Organization (PAO) in Thailand, the research explores the underlying causes of persistent non-compliance with motor vehicle tax obligations and evaluates innovative strategies to enhance revenue collection. As motor vehicle taxes constitute a vital source of income for local administrative bodies—supporting critical infrastructure and essential public services, chronic underpayment poses a significant fiscal challenge. Nationwide data indicate that over 10.27 billion baht in motor vehicle taxes remain uncollected annually. To address this issue, the study investigates structural inefficiencies within the tax collection process, including administrative bottlenecks and the lack of coordination between Provincial Transport Offices and local governments. Drawing upon behavioral insights, the research evaluates the efficacy of nudging strategies subtle, non-coercive interventions aimed at influencing taxpayer behavior. Specifically, the study tested the impact of personalized reminder letters sent to delinquent vehicle owners, with messaging crafted to highlight legal consequences, social norms, the societal value of public services, and civic duty. The findings reveal a statistically significant increase in tax compliance among recipients of the reminder letters, with the most pronounced effect observed in the group exposed to messages that emphasised legal penalties. These results underscore the potential of low-cost behavioural interventions to substantially improve the efficiency of tax collection. Importantly, the study estimates that if similar behavioural strategies were implemented across other provinces in the northeastern region—where tax delinquency remains high—they could help recover up to 41.35% of outstanding revenue, equivalent to more than 4.2 billion baht of the national total. Strengthening inter-agency collaboration, expanding accessible payment channels, and improving follow-up mechanisms for delinquent taxpayers are therefore recommended as key policy measures to promote sustainable local fiscal development.