6 January 2017Starting from the observation of taxpayers’ heterogeneity in terms of honesty andof the existence of a perverse social dynamic leading the most honest to evade, wepropose a simple mechanism to restore honesty. In a laboratory experiment, we testthe willingness of subjects to voluntarily contribute to a fund dedicated to financethe fight against tax evasion. This voluntary contribution mechanism, without redis-tribution, is analyzed thanks to several treatments that differ depending on the typeand the level of the required contribution. We show: (i) that a substantial numberof subjects contribute and that the frequency of contribution decreases with the in-crease in the level of contribution; (ii) that the most honest taxpayers are those whocontribute and (iii) that risk aversion deters subjects to contribute, while inequalityaversion encourages them. Finally, in line with the literature on tax evasion, we con-firm that the increase in the audit probability, which is observed only in groups wherethe collective contribution is sufficient, reduces evasion in these groups.