The engagement will run until March 31, with findings helping to ensure that future mental health services for veterans best meet their needs.
The NHS provides 12 mental health services across England specifically for veterans, which enable specialist staff to care for their mental health needs, direct them to the most appropriate service and give them effective treatment.
The services started in 2010 after the publication of Fighting Fit: a mental health plan for servicemen and veterans, by former surgeon-commander Dr Andrew Murrison MP, which called for extra support to be given to veterans.
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Launching the engagement, head of Health and Justice, Armed Forces and their Families and Public Health Commissioning Kate Davies said: "Most of the contracts for these services are due to end in September 2016. So this gives us an opportunity to ask what users think of them.
"The responses we receive will help us build on the strengths of our current mental health services for veterans and develop our future services. We want our services to be easily accessible to veterans, to take account of their experiences, and to give them high-quality and sensitive care, treatment and support – regardless of when they leave the armed forces."
It is estimated that more than 6 million ex-service personnel live in the UK, including spouses, widows, children and 2.8 million veterans.
While the rate of mental health problems among serving personnel and recent veterans seems to be broadly similar to that of the general UK population, a recent NHS England report said that "veterans aged 16 to 54 are more likely to experience common mental health problems.”
Working-age veterans are also more likely to report depression. Some also experience anxiety and post-traumatic stress disorder, which may involve alcohol or drug misuse.
To find out more and to complete the engagement survey, visit: www.engage.england.nhs.uk/survey/veterans-mental-health-services.