Any person who has a direct pecuniary interest in the resolution of a contested case may request to be admitted as an interested party with the agreement of all parties. Such persons must submit the request to the Tax Hearings Attorney assigned to the case. The Tax Hearings Attorney will transmit the request to the parties of record, and if the case is docketed at SOAH, to the assigned ALJ. If admitted, the interested party's participation will be limited to the extent of the party's interest.
34 Tex. Admin. Code § 1.24