This registration contains the data analysis plan for data collected from the fifth wave of the Optimising Wellbeing in Severe Mental Ill-Health (OWLS) project conducted by researchers at the University of York (OWLS 5). This project explores how the Covid-19 pandemic has affected people with severe mental illness, while also attempting to understand how the physical health and wellbeing of this population can be improved. The OWLS 5 survey asked questions related to the following domains: mental health and wellbeing; and employment/finance.