(a) A child custody evaluator may not offer an opinion regarding conservatorship of a child who is the subject of a suit or possession of or access to the child unless each basic element of a child custody evaluation as specified in this section and each additional element ordered by the court, if any, has been completed, unless the failure to complete an element is satisfactorily explained as provided by Subsection (b).
(b) A child custody evaluator shall:
(1) identify in the report required by Section 107.113 any basic element or any additional element of a child custody evaluation described by this section that was not completed;
(2) explain the reasons the element was not completed; and
(3) include an explanation of the likely effect of the missing element on the confidence the child custody evaluator has in the evaluator’s expert opinion.

(c) The basic elements of a child custody evaluation under this subchapter consist of:
(1) a personal interview of each party to the suit seeking conservatorship of, possession of, or access to the child;
(2) interviews, conducted in a developmentally appropriate manner, of each child who is the subject of the suit who is at least four years of age during a period of possession of each party to the suit but outside the presence of the party;
(3) observation of each child who is the subject of the suit, regardless of the age of the child, in the presence of each party to the suit, including, as appropriate, during supervised visitation, unless contact between a party and a child is prohibited by court order or the person conducting the evaluation has good cause for not conducting the observation and states the good cause in writing provided to the parties to the suit before the completion of the evaluation;
(4) an observation and, if the child is at least four years of age, an interview of any child who is not a subject of the suit who lives on a full-time basis in a residence that is the subject of the evaluation, including with other children or parties who are subjects of the evaluation, where appropriate;
(5) the obtaining of information from relevant collateral sources, including the review of:
(A) relevant school records;
(B) relevant physical and mental health records of each party to the suit and each child who is the subject of the suit;
(C) relevant records of the department obtained under Section 107.111;
(D) criminal history information relating to each child who is the subject of the suit, each party to the suit, and each person who lives with a party to the suit; and
(E) notwithstanding other law, records or information from any other collateral source that may have relevant information;
(6) for each individual residing in a residence subject to the child custody evaluation, consideration of any criminal history information and any contact with the department or a law enforcement agency regarding abuse or neglect; and
(7) assessment of the relationship between each child who is the subject of the suit and each party seeking possession of or access to the child.
(d) The court may order additional elements of a child custody evaluation under this subchapter, including the following:
(1) balanced interviews and observations of each child who is the subject of the suit so that a child who is interviewed or observed while in the care of one party to the suit is also interviewed or observed while in the care of each other party to the suit;
(2) an interview of each individual, including a child who is at least four years of age, residing on a full-time or part-time basis in a residence subject to the child custody evaluation;
(3) evaluation of the residence of each party seeking conservatorship of a child who is the subject of the suit or possession of or access to the child;
(4) observation of a child who is the subject of the suit with each adult who lives in a residence that is the subject of the evaluation;
(5) an interview, if the child is at least four years of age, and observation of a child who is not the subject of the suit but who lives on a full-time or part-time basis in a residence that is the subject of the evaluation;
(6) psychometric testing, if necessary, consistent with Section 107.110; and
(7) the performance of other tasks requested of the evaluator by the court, including:
(A) a joint interview of the parties to the suit; or
(B) the review of any other information that the court determines is relevant.