--- - |2 Abstract There have been numerous theories from numerous academic fields explaining why individuals engage in tax evasion. Drawing broadly on Social Identity Theory, we predict that exposure to one's national flag can reduce tax evasion by making salient one's national identity, motivating one to sacrifice one's self‐interests for one's country—which would presumably include paying one's fair share of taxes. In three experiments, we found that exposure to American, Australian, and British flags reduced Americans', Australians', and Britons' tax evasion in financially incentivized tasks (Experiments 1, 3) and increased tax‐paying attitudes (Experiment 2). The effects arose because flag primes made salient participants' national identities that then motivated them to help their country. We ruled out social norms and trust in authorities as alternative explanations. As such, flag primes might reduce tax evasion and in doing so improve the economic and societal welfare of a country. - European Journal of Social Psychology, EarlyView.