Allied health (AH) managers need to be able to quantify workloads to effectively manage the increasing demands on the health system. Workload allocation models provide a means of monitoring, evaluating and determining manageable workloads. This allows managers to ensure equitable distribution of duties and maximise the existing AH workforce output, which will lead to more efficient health service delivery and better patient outcomes. The purpose of this study was to develop and trial an AH workload allocation model incorporating the National Allied Health Casemix Committee Health Activity Classification. A workload allocation model was developed that included a staff workload mapping tool, data analysis spreadsheet and guidelines for calculating procedure times. The model was trialled across three AH professions (occupational therapy, physiotherapy and speech pathology), in two hospital districts, and across inpatient, outpatient and community settings. A total of 30 participants completed the trial. Staff and managers completed a post-trial survey to provide feedback on the workload allocation model. Survey results indicated that staff and managers found the model useful for evaluating and quantifying workloads. Managers believed the model would be useful for preparing business cases and benchmarking staff workloads. Recommendations for improvements to the workload mapping tool were also identified.