Most secondary (high) schools in a broad range of jurisdictions internationally engage in various forms of high stakes, standardized assessment and related qualifications. In this paper, we interrogate how educational achievement regimes -- especially via the reporting of curriculum and assessment 'data' -- continue to mobilize particular gender norms. Drawing on Derrida's notion of haunting we explore how such regimes impose and reinscribe stable and binary gendered patterning and create what Barad has named 'entangled relationalities of inheritance' [https://bibliotheek.ehb.be:2102/10.3366/drt.2010.0206,] despite young people (and many schools) moving towards greater recognition of non-binary genders. Drawing on assessment data from Aotearoa New Zealand, we look at both generalized reporting of educational achievement data along the lines of 'male' and 'female' and on reporting of a single (historically gendered) curriculum subject -- health education. We argue that such systems are 'haunted' by stable gender categorizations and hierarchies and we ask what this means for the reporting of educational assessment data and the erasure of identities that don't align with the binary.