Idaho Code § 50-1008

All special assessments levied in any city to which the provisions of this act are made applicable shall be due and payable to the city treasurer and, if not paid within thirty (30) days after mailing of notification of assessment, shall be declared delinquent and be certified to the tax collector of the county by the city clerk, not later than the first day of August and shall be by said tax collector placed upon the tax roll and collected in the same manner and subject to the same penalties as other city taxes; provided, however, that special assessments certified to the tax collector which are placed on property qualifying for a widow’s exemption may be returned to the taxing district from which they originated if the special assessments are not paid within three (3) years. All money received on special assessments shall be held by the city treasurer as a special fund to be applied to the payment of the improvement for which the assessment was made, and said money shall be used for no other purpose whatever unless to reimburse such city for money expended for such improvement.