This article explores the Brazilian carteira de trabalho (work card) and its usage on the sugarcane plantations of Alagoas, Northeast Brazil. It draws on photography and interviews with rural workers to analyse how documents have been used to manage and reproduce precarious work. On the plantations, work cards function as a managerial tool allowing workforce surveillance and control. Moreover, sugar mills can control rural workers’ mobility and shape the agricultural reserve army by retaining these documents, thereby immobilising wage workers. While the work card symbolises occupational citizenship and materialises the labour legislation, in practice, it becomes a disciplinary instrument supporting the agribusiness’ strategies of identification, control, and deployment of precariously employed and exploited labour on the plantations. Finally, the article contributes with an innovative historical–biographical approach to the study of institutional mechanisms used to produce and reproduce precarious work in Brazil’s sugarcane plantations.