Okla. Admin. Code § 710:1-5-100
When a taxing division contests the taxpayer's compliance with State tax laws or Commission rules, the taxing division may cause notice to be issued to the taxpayer requiring the taxpayer to appear before the Administrative Law Judge or an Administrative Hearing Officer to show why the taxpayer's license or permit should not be cancelled. The notice shall provide the owner of the license or permit twenty (20) days' notice of date and time of the hearing by registered or certified mail, return receipt requested. Failure to appear at the hearing may result in the cancellation of license or permit. The taxpayer may represent himself or herself or be represented by an attorney, an accountant or other representative approved by the Commission. The taxpayer is to bring all reports and payments for delinquent taxes, penalty and interest to the hearing. Evidence and testimony of witnesses may be presented at the hearing.
Okla. Admin. Code § 710:1-5-100