PurposeWhile the positive effects of customer citizenship behavior are well established, research on its potential negative consequences is scarce. This study aims to examine the indirect relationship between customer citizenship and dysfunctional customers via customer moral credits and entitlement, as well as the moderating influence of customer citizenship fatigue.Design/methodology/approachStudy 1 employed a cross-sectional design with a self-administered survey. The data were collected from 314 customers using an online research panel. In Study 2, the authors manipulated customer citizenship behavior using 203 participants to establish causality and rule out alternative explanations of the findings of Study 1. In Study 3, the authors replicated Study 2 and enhanced internal validity by using a more controlled experimental design using 128 participants.FindingsThis study shows that when customer citizenship fatigue is high, customer citizenship behavior elicits customer moral credit, which leads to customer entitlement and, in turn, promotes dysfunctional customer behavior. Conversely, when customer citizenship fatigue is low, customer citizenship behavior does not generate moral credit or entitlement, preventing dysfunctional customer behavior.Practical implicationsThe study shows that promoting customer citizenship behavior does not always lead to positive outcomes. Therefore, when promoting customer citizenship behavior, managers should consider the psychological licensing process and ways to mitigate the influence of moral credits.Originality/valueThis study challenges common wisdom and investigates the dark side of customer citizenship behavior. Specifically, it demonstrates that customer citizenship behavior could backfire (e.g. dysfunctional customer behavior). It also shows that only customers who experience a high level of fatigue from their citizenship behaviors are psychologically licensed to gain moral credit, leading to dysfunctional customer behavior.