When the property which is subject to school taxes is returnable annually to the tax commissioner or tax receiver of the county, that officer shall assess the property at the valuation fixed in the annual returns if that valuation is satisfactory to him. If the valuation fixed in the annual returns is not satisfactory to the tax commissioner or tax receiver, he shall make an assessment of the property within 30 days after receiving the return from the best information he can procure and he shall notify in writing the person or officer making the returns of the assessment. Each person or officer making a return may contest the taxability of the property within 20 days after receiving the notice. In lieu of requiring separate returns for purposes of school taxation, the assessment determined pursuant to this Code section, when completed and entered upon the tax digest, shall be adopted and used by the county boards of education or other school authorities authorized by law to levy taxes for school purposes in counties or school districts. Should the taxpayer desire to contest the taxability of the property under this Code section, he may do so by bringing an action for equitable relief in the superior court of the county where the property is assessed.