Utah Code § 54-3-22

Every public utility shall furnish to the commission at such time and in such form as the commission may require a report in which the public utility shall specifically answer all questions propounded by the commission upon or concerning any matter upon which the commission may desire information. The commission shall have authority to require any public utility to file monthly reports of earnings and expenses, and to file periodical or special, or both periodical and special, reports concerning any matter about which the commission is authorized to inquire or to keep itself informed or which it is required to enforce. All reports shall be under oath when required by the commission.