From the Expert: Even if you qualify for retired pay at age 58, you don’t qualify for TRICARE Prime or Select until you turn 60. However, you are eligible to purchase the premium-based TRICARE Retired Reserve (TRR) health plan for you and your eligible family members.
When you turn 60, you and your family become eligible for the same TRICARE health benefits as all other retired service members.
Learn more about this process at this link.