Utah Code Ann. § 59-2-1331 – Date tax is delinquent -- Penalty -- Interest -- Payments -- Refund of prepayment.

(1)
1. (a) Except as provided in Subsection (1)(b), all taxes, unless otherwise specifically provided for under Section 59-2-1332, or other law, unpaid or postmarked after November 30 of each year following the date of levy, are delinquent, and the county treasurer shall close the treasurer's office for the posting of current year tax payments until a delinquent list has been prepared.
2. (b) Notwithstanding Subsection (1)(a), if November 30 falls on a Saturday, Sunday, or holiday:
  1. (i) the date of the next following day that is not a Saturday, Sunday, or holiday shall be substituted in Subsection (1)(a) and Subsection 59-2-1332(1) for November 30; and
  2. (ii) the date of the day occurring 30 days after the date under Subsection (1)(b)(i) shall be substituted in Subsection 59-2-1332(1) for December 30.
(2)
1. (a) Except as provided in Subsection (2)(e), for each parcel, all delinquent taxes on each separately assessed parcel are subject to a penalty of 2.5% of the amount of the delinquent taxes or $10, whichever is greater.
2. (b) Unless the delinquent taxes, together with the penalty, are paid on or before January 31, the amount of taxes and penalty shall bear interest on a per annum basis from the January 1 immediately following the delinquency date.
3. (c) Except as provided in Subsection (2)(d), for purposes of Subsection (2)(b), the interest rate is equal to the sum of:
  1. (i) 6%; and
  2. (ii) the federal funds rate target:
    1. (A) established by the Federal Open Markets Committee; and
    2. (B) that exists on the January 1 immediately following the date of delinquency.
4. (d) The interest rate described in Subsection (2)(c) may not be:
  1. (i) less than 7%; or
  2. (ii) more than 10%.
5. (e) The penalty described in Subsection (2)(a) is 1% of the amount of the delinquent taxes or $10, whichever is greater, if all delinquent taxes and the penalty are paid on or before the January 31 immediately following the delinquency date.
(3) If the delinquency exceeds one year, the amount of taxes and penalties for that year and all succeeding years shall bear interest until settled in full through redemption or tax sale. The interest rate to be applied shall be calculated for each year as established under Subsection (2) and shall apply on each individual year's delinquency until paid.
(4) The county treasurer may accept and credit on account against taxes becoming due during the current year, at any time before or after the tax rates are adopted, but not subsequent to the date of delinquency, either:
1. (a) payments in amounts of not less than $10; or
2. (b) the full amount of the unpaid tax.
(5)
1. (a) At any time before the county treasurer mails the tax notice described in Section 59-2-1317, the county treasurer may refund amounts accepted and credited on account against taxes becoming due during the current year.
2. (b) Upon recommendation by the county treasurer, the county legislative body shall adopt rules or ordinances to implement the provisions of this Subsection (5).