Abstract This article posits that the multi-level governance literature can benefit from administrative burden theory if scholars are interested in understanding under which conditions policy implementation fails. To support this argument, we build on these two bodies of research to examine how implicit welfare rescaling – where the central government expands its role in a previously devolved policy – may increase administrative burdens for claimants, and to what extent local welfare systems can help to mitigate these burdens despite lacking coordination. To address these research aims, we assess the implementation of the “Ingreso Mínimo Vital,” a national minimum income scheme introduced in Spain within a fragmented regional system. Qualitative fieldwork with frontline professionals and policy experts shows that welfare rescaling heightened claimants’ administrative burdens due to inter-institutional misfit among governance levels. This imposed substantial learning, compliance, and psychological costs on claimants, making frontline professionals essential for guiding them through these challenges.