Tex. Estates Code § 1202.1521

Sec. 1202.1521. LETTER OR CERTIFICATE: REQUIREMENTS IF ALLEGED INCAPACITY BASED ON INTELLECTUAL DISABILITY. (a) If an intellectual disability is the basis of a ward's alleged incapacity, instead of the letter or certificate required under Section 1202.152(a), the court shall, subject to Subsection (c), consider a written letter or certificate the applicant presents from:

(1) a physician licensed in this state; or

(2) a psychologist licensed in this state or certified by the Health and Human Services Commission to perform the examination, in accordance with rules adopted by the executive commissioner of the commission governing examinations of that kind.

(b) The letter or certificate must:

(1) state, in the physician's or psychologist's opinion, whether the ward has the capacity, or sufficient capacity with supports and services, to do any of the activities listed in Section 1202.152(b)(1);

(2) state how or in what manner the ward's ability to make or communicate reasonable decisions concerning himself or herself is affected by the ward's mental capacity;

(3) include any other information required by the court; and

(4) be dated within the period prescribed by Section 1202.152(a)(1) or (2).

(c) The physician or psychologist who provides a letter or certificate under this section must preferably have experience examining individuals with an intellectual disability. For purposes of this subsection, a physician or psychologist is considered to have experience examining individuals with an intellectual disability if the physician or psychologist has an established patient-provider relationship with the ward.