© 2019 John Wiley & Sons Australia, Ltd Aim: Early Intervention Psychosis Services (EIPS) for people experiencing First Episode Psychosis (FEP) offer important clinical and non-clinical benefits over standard care. Similarly, intervention for Clinical High Risk for Psychosis state (CHR-P) can prevent psychosis, ameliorate symptoms and have non-clinical benefits. This study aimed to estimate associated local economic benefits of FEP and CHR-P services compared with standard care. Methods: Across four south London boroughs, proportion of annual number of new cases of FEP and CHR-P seen by early intervention services was estimated. Economic modelling conducted for England's mental health strategy was applied to estimate local economic impacts of current and improved service provision. Results: Across four London boroughs during 2011/2012, proportion of 15-34 year olds with FEP seen by EIPS was 100.2% assuming 80/100 000 annual incidence whereas proportion with CHR-P seen by CHR-P services was 4.1% assuming 200/100 000 annual incidence. Application of economic modelling suggests that provision of EIPS to reach all new FEP cases each year would free up resources of £13.1m over 10 years including £2.0m to National Health Service (NHS) after the first year. Scaling up to reach all new CHR-P cases each year would free up resources of £19.7m over 10 years with an estimated 10-year cost of implementation gap for each 1 year cohort of £18.9m. An earlier related briefing resulted in increased funding for EIPS and new CHR-P services despite overall cuts to mental health services. Conclusions: Estimation of local economic impacts of FEP and CHR-P services was associated with improved investment in such services.