From the Summary: "The Civilian Health and Medical Program of the Department of Veterans Affairs (CHAMPVA) was established by the Veterans Health Care Expansion Act of 1973 (P.L. 93-82). CHAMPVA is primarily a health insurance program where certain eligible dependents and survivors of veterans receive care from private sector health care providers. [...] To be eligible for CHAMPVA benefits, the beneficiary must be the spouse or child of a veteran who has a total and permanent service-connected disability, or the widowed spouse or child of a veteran who (1) died as a result of a service-connected disability; or (2) had a total, permanent disability resulting from a service-connected condition at the time of death; or (3) died while on active duty status and in the line of duty; and does not qualify for health care under the Department of Defense (DOD) TRICARE program."
CRS Report for Congress, RS22483
Congressional Research Service: https://crsreports.congress.gov/