Introduction Payment by results system in mental health services Payment by Results (PbR) is 'the payment system in England under which commissioners pay health care providers for each patient seen or treated, taking into account the complexity of the patient's health care needs' (Department of Health [DH] 2012). In April 2012, the DH mandated PbR to National Health Service (NHS) mental health services in England (DH 2009, Howitt 2009). PbR offers a means of increasing accountability for targeted service delivery and documentation of outcomes in a range of service areas including occupational therapy (DH 2011a, 2011b, 2010a, 2010b, 2009). The adoption of the PbR system is based on the care pathways and care packages approach (Self et al 2008). The approach was developed by South West Yorkshire Mental Health NHS Foundation Trust as a classification system that categorized working-age and older service users based on need. Service users were allocated to one of 20 'clusters', based on scores from the Mental Health Clustering Tool (MHCT), an instrument that incorporated items from the Health of the Nations Outcome Scales (HoNOS, Wing et al 1999) and the Summary of Assessments of Risk and Need (SARN, Self et al 2008).