Iowa Code § 326.16

1. If the fees for proportional registration are not paid to each contracting jurisdiction entitled thereto on the basis of the proportional registration application and supporting documents filed with the department by the fleet owner within a reasonable amount of time as determined by the department, the department shall calculate late payment penalties. The fleet owner shall be notified by regular mail that fees and penalties are due and must be paid within thirty days of the invoice date. If fees and penalties are not received, the fleet owner shall be notified by certified mail that the owner’s registration has been suspended.

2. A five percent late payment penalty shall be assessed if an invoice is not paid within thirty days of the invoice date or within thirty days of January 31 of the registration year, whichever is later, with an additional five percent penalty assessed the first of each month thereafter until all fees and penalties are paid. In addition, the fees due for registration in this state shall be a debt due to the state of Iowa.

3. Failure to receive a renewal notice or an invoice by mail, facsimile transmission, or any other means of delivery does not relieve the registrant of the financial responsibility for the renewal fees, invoiced amount, or accrued penalties.