Do Behavioral Nudges in Prepopulated Tax Forms Affect Compliance? Experimental Evidence with Real Taxpayers

Defaults, in the form of prepopulated fields within the tax form, have been identified as potential mechanisms that tax authorities can use to reduce noncompliance. They achieve this by simplifying the process of filing taxes, thus reducing the scope for errors. However, defaults may increase the scope for evasion if set incorrectly. The authors report experimental data on the effect of correct and incorrect defaults. They find that prepopulating tax returns is a worthwhile policy only if it is done with highly reliable information. Setting default levels that underestimate taxpayers' true tax liability leads to significant drops in compliance and tax revenue. The authors also study whether nudges that contain messages with descriptive norms about compliance can mitigate the adverse effect of prepopulated returns with incorrect values. Nudges that react to inputs from the taxpayer effectively raise compliance, whereas static nudges do not. This result demonstrates the limits to the applicability of nudges in a public policy sphere as well as possible adverse effects resulting from poor implementation.