Payment by results (PbR) is a payment platform for healthcare services. Introduced to acute physical healthcare services in England in 2003–2004, the system has continued to expand and is currently being implemented in acute mental health services. Owing to the variations and complexities of the patients who access specialist psychiatric services, existing clusters do not always accurately capture their needs. The development of PbR tools specific to psychiatric subspecialties is ongoing, but might not be available in the short term. The funding of acute mental health services through PbR might have funding implications for specialist services such as psychiatry of intellectual disability.