28 Tex. Admin. Code § 21.3806
A health benefit plan issuer may refuse to provide all or part of an eligibility statement if applicable state or federal law prevents the disclosure of an enrollee's or dependent's personally identifiable information to the requesting participating provider. A health benefit plan issuer that refuses to provide all or part of an eligibility statement shall provide a response to the request for an eligibility statement indicating the reason(s) for refusing to provide the information. Within three days of refusing to provide an eligibility statement under this section, a health benefit plan issuer shall provide a written response indicating the reason(s) for refusing to provide the information and describing the particular state or federal law provision(s) that prevent the disclosure.
28 Tex. Admin. Code § 21.3806