It is essential that you keep information in the Defense Enrollment Eligibility Reporting System (DEERS) current for you and your family. DEERS is a worldwide computerized database of uniformed service members (active duty and retired), their family members, and others who are eligible for military benefits, including TRICARE. The key to receiving timely, effective TRICARE benefits—including doctor appointments, prescriptions, payment of health care expenses, etc.—is proper and current registration in DEERS.
Registering in DEERS does not mean you are enrolled in TRICARE. To enroll in TRICARE Prime you must complete an enrollment form and mail it or turn it in at the TRICARE Service Center. You may also enroll on-line through the beneficiary web enrollment application