Per Utah state law, the penalty for delinquent taxes is 2.5% (or $10, whichever is greater). However, the penalty is reduced to 1% (or $10, whichever is greater) if all 2017 delinquent taxes and the 1% penalty are paid on or before January 31, 2018.
Interest will be charged after January 31, 2018, effective January 1, 2018.