Iowa Code § 443.13: Action by treasurer — apportionment.

Upon failure to pay such sum within thirty days, with all accrued interest, the treasurer shall cause an action to be brought in the name of the treasurer for the use of the proper county, to be prosecuted by the county attorney, or such other person as the board of supervisors may appoint, and when such property has been fraudulently withheld from assessment, there shall be added to the sum found to be due a penalty of fifty percent upon the amount, which shall be included in the judgment. The amount thus recovered shall be by the treasurer apportioned ratably as the taxes would have been if they had been paid according to law.