Supplementary material for "Rebuilding Trust, Restoring Compliance: An Experimental Study of Tax Morale among Young Taxpayers"

Improving voluntary tax compliance has become a critical challenge for developing economies, where limited enforcement capacity often constrains the effectiveness of traditional deterrence-based tax policies. While previous studies highlight the importance of social norms and institutional trust in shaping tax behavior, limited experimental evidence examines how normative environments interact with fiscal policy signals such as tax amnesties. This study investigates how social norms and tax amnesty policies influence tax morale while controlling for trust in government. The analysis draws on data from a scenario-based factorial experiment involving 300 undergraduate students from four public universities in Southern Sumatra, representing emerging taxpayers whose fiscal attitudes are still forming. A 2 × 2 between-subjects experimental design was implemented, and the data were analyzed using analysis of covariance (ANCOVA) in R to estimate the main and interaction effects of social norms and tax amnesty.