7 October 2019This paper reports an experimental test of the relative efficiency of a whistleblowing-based audit scheme compared to a random-based audit scheme. We design a between-subjects laboratory experiment with two treatments: a benchmark with a random-based audit scheme and an alternative treatment in which taxpayers can blow the whistle. Compared to the benchmark, the whistleblowing-based audit scheme (i) improves the targeting of evaders, (ii) decreases the monetary amount of tax evasion, and (iii) raises the tax levy.