Idaho Code § 63-1001

To avoid delinquency, total payment must be made in full to the county tax collector by the due date. Any delinquency shall have the force and effect of a sale to the county tax collector as grantee in trust for the county of the property described. Any payment on a delinquency is, in effect, a partial redemption of the property from tax sale. Interest on a delinquency will be charged at one percent (1%) per month calculated from January 1 following the year the tax lien attached, provided however, that the interest shall not be charged on collection costs.