The state tax commission must complete the equalization of assessments throughout the state during its meeting as the state board of equalization, after receipt of each county auditor’s abstract of the property roll, no later than the fourth Monday of August in the year in which such assessments are made, and, if there is to be a state property tax, shall on that day determine the amount of state property tax which each county must collect and remit to the state, by apportioning the total state property tax among the several counties in the state in the exact proportion that the total equalized valuation of each county, as shown by the property roll for the current year, and the subsequent and missed property rolls for the preceding year, bears to the total equalized valuation of the state from such rolls of all the counties in the state. The state tax commission shall also determine the amount of special state taxes, if any, which each county must collect and remit to the state, and the total amount of such state property and special state taxes found to be due from each county shall be certified to the county auditor of such county by the chairman of the state tax commission, and the county auditor shall, upon receipt of such certificate, file the same in his office; provided, that the total amount of all special state taxes levied for the current year upon property entered upon the subsequent and missed property rolls of each county for such year shall be certified to the county auditor of such county by the chairman of the state tax commission upon receipt of the county auditor’s abstract of the subsequent and missed property rolls.