The county clerk, when making out the tax books for the State and county tax for the collector, shall in each year extend the special tax in separate columns against each taxpayer’s name or taxable property in the district, as other taxes are extended, which shall be collected the same as State and county taxes, and known as the permanent road fund of the district; provided that such special tax shall not be extended in any road district located in any county in which a county unit road district has been established after the effective date, as provided in Section 6-125 of this Code, upon which the county takes over and becomes responsible for the construction, maintenance and repair of all county unit district roads in such county.