This interim final rule implements the primary features of section 701 and partially implements several other sections of the National Defense Authorization Act for Fiscal Year 2017 (NDAA-17). The law makes significant changes to the TRICARE program, especially to the health maintenance organization (HMO)-like health plan, known as TRICARE Prime; to the preferred provider organization health plan, previously called TRICARE Extra and now to be called TRICARE Select; and to the third health care option, known as TRICARE Standard, which will be terminated as of December 31, 2017, and replaced by TRICARE Select. The statute also adopts a new health plan enrollment system under TRICARE and new provisions for access to care, high value services, preventive care, and healthy lifestyles. In implementing the statutory changes, this interim final rule makes a number of improvements to TRICARE. Specifically, this rule will enhance beneficiary access to health care services, including increased geographic coverage for the TRICARE Select provider network, reduced administrative hurdles for TRICARE Prime enrollees to obtain urgent care services and specialty care referrals, and promotion of high value services and medications and telehealth services. It will also expand TRICARE coverage of preventive care services and prevention and treatment of obesity and refining cost-benefit assessments for TRICARE plan specifications that remain under DoD's discretion.