Utah Code § 59-5-210

Every decision of the commission shall be in writing and notice of the decision shall be mailed to the taxpayer within 10 days. All decisions become final upon the expiration of 30 days after notice has been mailed to the taxpayer, unless proceedings are taken within such time for a review in accordance with Title 63G, Chapter 4, Administrative Procedures Act, in which case it becomes final as specified in the Administrative Procedures Act.