From and after January first, one thousand nine hundred and thirty-seven the proper authorities of each city of the second class A, and of the school district, and poor district, within or coextensive therewith or having territory therein, charged with the levying of taxes within the territorial limits of cities of the second class A, shall annually levy their respective taxes and cause the same to be collected at the same time or times as required by existing law for the levy and collection of county taxes in such cities: Provided, however, That all taxables shall have the right to make payment of all such taxes by installment payments thereon, as provided under existing law.
53 P.S. § 30754