This article investigates changes in the right to social assistance – a means-tested cash support programme, regulated by the Social Services Act – for irregularised migrants over a period of four decades, 1982–2022. The article makes the case that austerity policies have hollowed out the right to support, with significant repercussions for those with irregularised residency status. In doing so, it draws on a range of empirical data to shed light on the dynamics of legal change over time and across various settings, identifying both continuities and critical turning points. The latter include shifts in national or local migration policies, and novel intersections between migration law and social law, epitomised by court judgments that have redrawn the lines of inclusion and exclusion in the sphere of rights holders. The article also highlights continuous issues concerning inconsistencies in the legal sources made used of by courts, neglect of children’s interests and needs, and an application of requirements for participation in work-related activities that disadvantage migrants and citizens alike. Ultimately, the article offers insights into how social rights can be preserved in the context of increasingly restrictive migration and social policies.