Utah Code § 34-44-201
§ 34-44-201. Written business relationship.
(1) The business relationship between a sales representative and a principal shall be in a writing signed by both the principal and the sales representative. (2) The writing required by Subsection (1) shall set forth the method by which the sales representative's commission is: (a) computed; and (b) paid. (3) The principal shall provide the sales representative with a copy of the signed writing required by Subsection (1).