Armed groups tax. Journalistic accounts often include a tone of surprise about this fact, while policy reports tend to strike a tone of alarm, highlighting the link between armed group taxation and ongoing conflict. Policymakers often focus on targeting the mechanisms of armed group taxation as part of their conflict strategy, often described as ‘following the money’. We argue that what is instead needed is a deeper understanding of the nuanced realities of armed group taxation, the motivations behind it, and the implications it has for an armed group’s relationship with civilian and diaspora populations, as well as the broader international community. This paper builds on two distinct literatures, on armed groups and on taxation, to provide the first systematic exploration into the motivation of armed group taxation. Based on a review of the diverse practices of how armed groups tax, we highlight that a full account of their motivation needs to go beyond revenue collection, and engage with key themes around legitimacy, population control, institution building, and the performance of public authority. We problematise common approaches towards armed group taxation and state-building, and outline key questions of a new research agenda.