Each ad valorem property tax of a taxing district shall apply to all the taxable property of the district, or to all the taxable property in a tax zone of a district that has established two or more tax zones within the district, as shown by the assessment roll last compiled by the assessor. The assessor, upon the application of the governing body or of the duly accredited officer of any such taxing district, shall furnish a certificate, properly verified, showing the aggregate valuation of the taxable property therein.
ORS 310.100