Tex. Human Resources Code § 32.0214

(a) If the commission determines that it is cost-effective and feasible and subject to Subsection (b), the commission shall require each recipient of medical assistance to designate a primary care provider with whom the recipient will have a continuous, ongoing professional relationship and who will provide and coordinate the recipient's initial and primary care, maintain the continuity of care provided to the recipient, and initiate any referrals to other health care providers.

(b) A recipient who receives medical assistance through a Medicaid managed care model or arrangement under Chapter 540 or 540A, Government Code, as applicable, that requires the designation of a primary care provider shall designate the recipient's primary care provider as required by that model or arrangement.