The initial implementation design of EU’s asylum policy, reflective of the theory of executive federalism, foresaw that national authorities were to conduct asylum processing. This design shifted and patterns of joint implementation surfaced. Joint implementation broadly refers to staff and experts deployed by the European Asylum Support Office (EASO), an EU agency, working alongside national administrators, including on asylum processing. I scrutinize these patterns and the resulting accountability challenge, drawing from legal analysis, political science theories, and administrative practice. EASO is subject to a mosaic of accountability processes. Two main pitfalls emerge: the balance between accountability and independence; and accessibility for the individual. Against this backdrop, I focus on extra-judicial accountability through the European Ombudsman which, combined with the envisaged internal “individual complaints mechanism”, could help ensure applicants’ procedural rights.