beliefs about groups who are generally believed to exploit the tax system would be most effective, even if the subject is not a member of these groups.

The obvious group to use to distinguish these two effects is rich people. There is substantial reason for citizens to believe that the rich in society are not paying their full tax burden. The Panama Papers revealed the extent to which wealthy citizens around the world have been using various legal and extralegal methods to avoid paying tax in their home countries (Harding 2016). Similarly, companies are able to use various accounting mechanisms and legal structures to pay rates well below the formal rates (for instance the average corporate tax rate actually paid by US companies was 12.1% of profits in 2011 compared to a headline rate of 39.1% (Paletta 2011)).

The mechanism behind social norms treatments is important to understand because it affects what tax authorities should prioritize in terms of messaging and enforcement. If descriptive norms are the relevant mechanism, then focusing enforcement efforts on average taxpayers will be most effective because it will change the descriptive norms that are relevant to the most people. However, if the free-rider mechanism is the important one, it suggests that tax authorities should instead focus their enforcement efforts on visibly cracking down on tax evasion by groups who are most seen as exploiting the system, such as the richest taxpayers (Motel 2015).

We compare three different social norm treatments focusing on the tax paying behavior of people generally, rich people and companies. On the reference group account, only the people treatment should be effective, while the avoiding being a sucker account would predict that all treatments could be effective but especially the rich people and companies treatments.

We ran this survey in five English speaking countries covering a variety of development and tax compliance levels: Kenya, Australia, the United States, the Philippines, and South Africa. Our results support the free-rider interpretation of social norm interventions. We find large effects of priming rich people’s tax compliance (our treatments all suggest that tax compliance is relatively high) on two measures of tax morale. However, we find no evidence of an effect of priming ordinary people’s tax compliance and only a weak non-significant effect of priming corporate tax compliance.

# Study design

We split respondents into four experimental groups: three treatment groups and a control group.

The first treatment gave a standard descriptive norms message: “Last year most [country] citizens paid the tax they owed. It is uncommon for people to cheat on their taxes.” To reinforce this message (and implicitly get respondents to endorse it), we asked “Do you think it is a good thing that most people are paying their taxes?” with the response options yes and no.

The other two treatments emphasized the tax paying behavior of groups the respondent would not be expected to belong to but are generally believed to have high rates of tax evasion. Either “Last year most rich [country] citizens paid the tax they owed. It is uncommon for rich people to cheat on their taxes.” or “Last year most [country] companies paid the tax they owed. It is uncommon for companies to cheat on their taxes,” with follow-up questions “Do you think it is a good thing that most rich people are paying their taxes?” and “Do you think it is a good thing that most companies are paying their taxes?” respectively.