A city may establish a self-supported improvement district operation fund, and may certify taxes not to exceed the rate limitation as established in the ordinance creating the district, or any amendment thereto, each year to be levied for the fund against all of the property in the district, for the purpose of paying the administrative expenses of the district, which may include but are not limited to administrative personnel salaries, a separate administrative office, planning costs including consultation fees, engineering fees, architectural fees, and legal fees and all other expenses reasonably associated with the administration of the district and the fulfilling of the purposes of the district. The taxes levied for this fund may also be used for the purpose of paying maintenance expenses of improvements or self-liquidating improvements for a specified length of time with one or more options to renew if such is clearly stated in the petition which requests the council to authorize construction of the improvement or self-liquidating improvement, whether or not such petition is combined with the petition requesting creation of a district. Parcels of property which are assessed as residential property for property tax purposes are exempt from the tax levied under this section except residential properties within a duly designated historic district or property classified as residential property under section 441.21, subsection 14, paragraph “a”, subparagraph (6). A tax levied under this section is not subject to the levy limitation in section 384.1.