AbstractIntroductionWe will use a sub-sample of a current longitudinal study to investigate the impact of COVID-19 on the health and wellbeing of ex-service personnel in the UK. The study will provide evidence for the UK Office of Veterans’ Affairs (OVA), UK stakeholders supporting the ex-service community, and evidence to inform our international counterparts working with ex-service communities in allied countries regarding the impact of COVID-19 on the health and wellbeing of ex-service personnel.Methods and analysisParticipants were eligible to participate if they lived in the UK, had Regular service history from the UK Armed Forces and had previously completed the King’s Centre for Military Health Research (KCMHR) Health and Wellbeing survey between 2014–2016. Participants who met these criteria were recruited through email to take part in an online questionnaire. The study provides additional quantitative longitudinal data on this sub-sample. Data are being collected June 2020-September 2020. Specific measures are used to capture participants’ COVID-19 experiences, health and wellbeing status and lifestyle behaviours. Other key topics will include questions regarding the impact of COVID-19 pandemic on employment, finances, volunteering, charitable giving, accommodation and living arrangements, help-seeking behaviours, as well as any potential positive changes during this period.Ethics and DisseminationEthical approval has been gained from King’s College London Research Ethics Committee (Ref: HR-19/20–18626). Participants were provided with information and agreed to a series of consent statements before enrolment. Data are kept on secure servers with access to personally identifiable information limited. Findings will be disseminated to the OVA, UK ex-service stakeholders and international research institutions through stakeholder meetings, project reports and scientific publications.Strengths and limitations of this studyStrengths include recruitment from a population where underlying characteristics are known, and longitudinal data is held on their health and wellbeing.There has been rapid roll-out of the survey to ensure relevance for participants’ COVID-19 experiences and use of validated measures for mental health and wellbeing outcomes.Study limitations include recruitment from a specific cohort; hence the study cannot comment on the impact of COVID-19 in other veteran populations.