There is an ample literature on the determinants of tax compliance. Several field experiments have evaluated the effect and comparative relevance of sending deterrence and moral suasion messages to taxpayers. The effect of different delivery mechanisms, however, has not been evaluated so far....

Most tax agencies use letters as the method of communicating with taxpayers. Still, other technologies exist that could be more effective. This paper reports the results of a field experiment conducted by the National Tax Agency of Colombia (DIAN), using phone calls to reduce tax delinquencies....