The Defense Enrollment Eligibility Reporting System (DEERS) is a computerized data bank that lists all active and retired military members and their dependents if they meet the eligibility requirements. Active and retired military members are automatically listed but must take action to list their dependents and report any changes to family members' status (marriage, divorce, birth of a child, adoption, etc.) along with changes to mailing addresses. TRICARE contractors check DEERS before processing claims to make sure patients are eligible. You may contact DEERS at 1-800-538-9552.