Sections 63-3045, 63-3073, Idaho Code
The annual rate of interest applicable to delinquent taxes accruing or unpaid during all or any part of a calendar year is determined in accordance with Section 63-3045, Idaho Code. The rates are listed at https://tax.idaho.gov/interest. These interest rates also apply to the allowance of a credit or refund of tax erroneously or illegally assessed or collected as provided in Section 63-3073, Idaho Code.
Idaho Admin. Code r. 35.02.01.310