31 Tex. Admin. Code § 17.29
The rules of evidence as applied in nonjury civil cases in the district courts of this state shall be followed. Irrelevant, immaterial, or unduly repetitious evidence may be excluded. When necessary to ascertain facts not reasonably susceptible to proof under those rules, evidence not admissible under them may be admitted (except where precluded by statute) if it is of a type commonly relied upon by reasonably prudent people in the conduct of their affairs. The rules of privilege recognized by law shall be effective in agency proceedings. Objections to evidentiary offers may be made and shall be noted in the record. Subject to these requirements, if a hearing will be expedited and the interests of the parties will not be prejudiced substantially, any part of the evidence may be received in writing.
31 Tex. Admin. Code § 17.29