Any ordinance assessing a tax pursuant to this act shall contain a finding by the local governing body of the city based upon evidence presented to it that the condition set forth in section 50-1044, Idaho Code, exists and shall provide the methods for reporting and collecting taxes due. Taxes collected pursuant to any such ordinance shall be remitted to the city official designated in such ordinance or other such official contracting, pursuant to this act, with the city to provide collection services, and shall constitute revenue of the city available for any lawful corporate purpose approved by city voters subject to the provisions of this act. In any election, the ordinance submitted to city voters shall: (a) state and define the specific tax to be approved; (b) state the exact rate of the tax to be assessed; (c) state the exact purpose or purposes for which the revenues derived from the tax shall be used; and (d) state the duration of the tax. No tax shall be redefined, no rate shall be increased, no purpose shall be modified, and no duration shall be extended without subsequent approval of city voters. An ordinance adopting any local-option nonproperty tax authorized by this act may provide for separate identification of taxes as may be appropriate. The city clerk of any city adopting an ordinance pursuant to this act shall, immediately following approval of such ordinance, or any amendment thereto, forward a copy of said ordinance or amendment to the chairman of the state tax commission, and the chairman of the state board of tax appeals.