Utah Code § 81-5-609
§ 81-5-609. Limitation -- Child having declarant father.
(1) If a child has a declarant father, a signatory to the declaration of paternity or denial of paternity or a child support services agency may commence a proceeding seeking to rescind the declaration or denial or challenge the parentage of the child only within the time allowed under Section 81-5-306 or 81-5-307. (2) A proceeding under this section is subject to the application of the principles of estoppel established in Section 81-5-608.