Digital citizenship education (DCE) is a concept that looks to develop learners as competent, critical, and active participants in digitally connected societies. "The New Zealand Curriculum" ("NZC") conveys a vision of DCE across subject disciplines, yet digital citizenship is scarcely defined in teaching content or learning objectives. This article reviews existing conceptions of DCE and their position in curricula, before using a postdigital lens to develop a novel conception, "speculative DCE." This conception is rooted in the need to examine knowledge, issues, and speculative visions of the future through and beyond different subject disciplines. "NZC" and accompanying documents are assessed for their applicability to accommodate different conceptions of DCE. Analysis suggests that the emphasis on a future-focused approach, combined with curriculum integration, has scope for unpacking sociotechnical relations, developing transdisciplinarity, and enacting speculative DCE.