Experimental Design
We will analyze treatment effects separately by distance to the tunnel, comparing taxpayers who are closer versus farther away (using pre-defined distance bins defined as 0-1.5km, 1.5-3km,3-5km,+5k. This heterogeneity is central because the intervention is explicitly about making the benefits of the project salient, and proximity is a natural proxy for expected individual benefit. If the tax–benefit linkage matters, effects should be stronger among those with higher exposure to the project (closer properties). At the same time, the sign is not mechanically pinned down: some taxpayers may react positively to learning that their taxes finance a visible local investment, while others may react negatively if they perceive the project as irrelevant, poorly targeted, or not worth the cost, even if they live nearby. We will also report pooled effects across all distances.
We will explore heterogeneity by baseline compliance (past payment history). We expect larger effects among taxpayers who have a margin to adjust, such as occasional or late payers, and smaller effects among never-payers and always-on-time payers. Never-payers may be less responsive to informational content because nonpayment is likely driven by constraints or persistent disengagement, while consistently compliant taxpayers have limited room to increase compliance.