Idaho Code § 50-1721A
Whenever any land against which there has been levied any special assessment by any municipality shall have been sold in part or subdivided, the council of that municipality shall have the power to order a segregation of the assessment.
Any person desiring to have such a special assessment against a tract of land segregated to apply to smaller parts thereof shall apply to the municipality which levied the assessment. If the council determines that a segregation should be made, it shall by ordinance order the clerk to make segregation on the original assessment roll as directed in the ordinance. The segregation shall be made as nearly as possible on the same basis as the original assessment was levied, and the total of the segregated parts of the assessment shall equal the assessment before segregation. The ordinance shall describe the original tract, the amount and date of the original assessment, and shall define the boundaries of the divided parts and the amount of the assessment chargeable to each part. A certified copy of the ordinance shall be filed with the county recorder. The council may require, as a condition to the order of segregation, that the person seeking it pay the municipality the reasonable engineering and clerical costs incident to making the segregation. No segregation need be made if the council shall find that by such segregation the security of the lien for such assessment will be so jeopardized as to reduce the security for any outstanding local improvement district obligations payable from such assessment.
Idaho Code § 50-1721A