Utah Code Ann. § 59-7-513
If the time for payment of the amount determined as the tax by the taxpayer is extended under the authority of Subsection 59-7-507(2), there shall be collected as a part of such amount interest at the rate prescribed in Section 59-1-402 from the date when such payment should have been made, if no extension had been granted, until payment is received.
Amended by Chapter 1, 1993 Special Session 2