24 Pa. Stat. § 6-676
In all school districts of the third class, excepting school districts of that class which are located wholly within the boundary lines of cities of the third class and where such third class school districts comprise the same territory as such city of the third class in which the same is so located, and in all school districts of the fourth class, the school taxes shall be levied and assessed upon all the property upon which the county taxes are levied and assessed.
In all school districts of the third class which are located wholly within the boundary lines of any city of the third class, and where such third class school district comprises the same territory as such city of the third class in which the same is so located, the school taxes shall be levied and assessed on the real estate and personal property therein as contained in the assessment made for city tax purposes: Provided, That in any such school district of the third class which is situated within a county of the fourth to the eighth class, the board of school directors may, by resolution, accept the provisions of "The Fourth to Eighth Class County Assessment Law" irrespective of whether or not the city has accepted the provisions of such assessment law, and in such case the school taxes shall be levied and assessed upon all the property upon which the county taxes are levied and assessed.
24 P.S. § 6-676