This study investigates the impact of social norms (descriptive, injunctive, subjective and personal norms) on small business owners' tax compliance intentions during the Australian federal government's $88.8 billion JobKeeper support scheme, implemented during COVID-19 to provide financial relief for affected businesses. Using survey data from 252 small business owners and structural equation modelling, we find that small business owners' own standards of tax compliance behaviour are determined mainly by what their peers (other business owners) actually do in a given situation (descriptive norms) and indirectly by what their coworkers, family and friends expect them to do (subjective norms), but not by general expectations of acceptable behaviour within society (injunctive norms). This suggests that during a crisis situation, where societal injunctive norms have not yet formed, small business owners' tax compliance behaviour is more strongly driven by what their peers 'actually do' than by what others think 'ought' to be done. In further analysis, we find that business owners with low tax compliance intentions are more likely to have overstated their anticipated decline in turnover, meaning they received the JobKeeper subsidy although their businesses were ineligible based on actual earnings. Taken together, these findings suggest that during periods of social norm formation, taxpayers engage in information processing, which allows them to portray themselves as morally appropriate relative to their peers yet pursue economic goals of personal benefit. By identifying the social norms that determine tax compliance in a crisis situation, a normative intervention and communication strategy can be developed by tax authorities to guide the formation of taxpayers' social norms and discourage tax evasion practices in future crises.