The county board or court may make supplemental assessments to correct omissions, errors, or mistakes in the assessment relating to the total cost of the improvement or any other particular, or whenever it is ascertained that the collections of special assessments and interest thereon, together with the net revenues of the system, are not sufficient to pay all bonds issued to finance the system and interest thereon when due. A supplemental assessment shall be preceded by personal or mailed notice to the owner of each parcel included in the supplemental assessment and a hearing as provided for the original assessment.
When an assessment is, for any reason, set aside by a court of competent jurisdiction as to any parcel or parcels of land, or in event the board or court finds that the assessment or any part thereof is excessive, or determines on advice of the county attorney that the assessment or proposed assessment or any part thereof is or may be invalid for any reason, the board or court may, upon notice and hearing as provided for the original assessment, make a reassessment or a new assessment as to such parcel or parcels.
When a tract of land against which a special assessment has been levied is thereafter divided or subdivided by plat or otherwise, the board or court may, on application of the owner of any part of the tract or on its own motion equitably apportion among the various lots or parcels in the tract all the installments of the assessment against the tract remaining unpaid and not then due if it determines that such apportionment will not materially impair collection of the unpaid balance of the original assessment against the tract. The board or court may, and if the special assessment has been pledged to the payment of improvement warrants shall, require the owner or owners, as a condition of such apportionment, to furnish a satisfactory surety bond fully protecting the county against any loss resulting from failure to pay any part of the reapportionment assessment when due. Notice of such apportionment and of the right to appeal shall be mailed to or personally served upon all owners of any part of the tract. Within 30 days after the mailing or service of the notice of such apportionment any such owner may appeal as provided in section 116A.19.