Idaho Code § 63-3503B
Every producer of electricity by means of wind energy, by means of solar energy or by means of geothermal energy in this state shall file with the state tax commission of the state of Idaho an operator's statement in the manner as provided for in section 63-404, Idaho Code, and shall include thereon a statement of the prior calendar year's gross wind energy earnings, gross solar energy earnings or gross geothermal energy earnings. Upon examining and verifying said statement, the state tax commission shall compute the amount of the wind energy tax, solar energy tax or the geothermal energy tax based on the gross wind energy earnings, gross solar energy earnings or the gross geothermal energy earnings and shall allot to each county in which the property of such producer is situated, and otherwise exempted from taxation by section 63-602JJ, Idaho Code, either: that proportion of the total wind energy tax, that proportion of the total solar energy tax or that proportion of the total geothermal energy tax of such producer shown to be due as the same proportion that the total original cost of property situated in such county, and otherwise exempted from taxation by section 63-602JJ, Idaho Code, bears to the total original cost of such property of such producer for the wind energy project, of such producer for the solar energy project or of such producer for the geothermal energy project. The state tax commission shall then, for each county, apportion the wind energy tax, solar energy tax or geothermal energy tax so allotted to such county among the several taxing units thereof within which any property of such producer is situated, and otherwise exempted from taxation by section 63-602JJ, Idaho Code, by apportioning to each such taxing unit that proportion of the wind energy tax, solar energy tax or geothermal energy tax so allotted to such county. For such apportionment, the state tax commission shall calculate the weighted original cost which shall be the product of the original cost of such property within such taxing unit times such taxing unit's property tax levy for the prior year and the weighted apportionment rate which shall be the ratio of the wind energy tax, of the solar energy tax or of the geothermal energy tax, as the case may be, allotted to such county, to the aggregate weighted original cost for all such taxing units within which the property is located and then shall calculate the apportionment of the wind energy tax, solar energy tax or geothermal energy tax for each such taxing unit to be equal to the product of the weighted original cost times the weighted apportionment rate. The state tax commission shall, on or before the third Monday in May, notify the state superintendent of public instruction, the county auditor, and the county treasurer of such allotment and apportionment and the amounts thereof. On or before the first Monday in August, the county auditor shall notify the appropriate taxing units of the amount of wind energy tax, the amount of solar energy tax or the amount of the geothermal energy tax being apportioned and the amount of the solar energy tax distributed to each of these taxing units during the twelve (12) months immediately preceding July 1 of the current tax year.
Idaho Code § 63-3503B