Idaho Code § 50-1739
As soon as any assessment or instalment thereof, of any local improvement district shall become delinquent, the treasurer shall, if such assessment be collected in one (1) payment, mark the same delinquent on the assessment roll, or if for an instalment of an assessment, on the "Local Improvement Instalment Docket," and shall add to the amount shown on said assessment roll, or instalment docket, a penalty of two per cent (2%) thereon. Within ten (10) days thereafter the treasurer shall prepare and issue to the municipality, in which such local improvement district is located, a delinquency certificate to the property included in each such delinquent assessment or instalment, which certificate shall have the force and effect of a sale of said property to the municipality for the amount thereof, said certificate shall bear date as of the time such assessment or instalment became delinquent and shall be for the amount thereof plus the penalty charged thereon. Such certificate shall contain, besides the description of the property to be sold, the name of the person assessed, if known, or if unknown, that fact, the amount of the assessment of instalment, plus penalty thereon; the number of the assessment and the name of the improvement district in which assessed; the date when such certificate will go to deed and shall bear interest from date thereof at the rate of ten per cent (10%) per annum. Such certificates shall be made in duplicate, bound together in books in numerical order and filed in the office of the treasurer; provided, that after one (1) such certificate has been issued no further delinquency certificate shall be issued for subsequent instalments of the same assessment, except as hereinafter provided, and whenever any subsequent instalment shall thereafter become delinquent the treasurer shall so mark the same in the instalment docket and add the penalty thereto, as hereinbefore provided, and the same shall draw interest at the rate of ten per cent (10%) per annum from date of delinquency until the end of the month in which it is paid.
Idaho Code § 50-1739