Where lands situate in one county now are or hereafter shall be annexed to a borough situate in an adjoining county, the authorities in the county wherein the land is actually situated, now or hereafter having authority to make the assessments on which the county and poor taxes are levied shall assess the taxable property within the lines of land lying in such county, and shall record the same in a separate book. This assessment shall be made by the authority that would have made the assessment had the land not been annexed to the borough. The owners of all property so assessed shall have the same right of appeal from this assessment as any other taxable in the same county.
72 P.S. § 5020-420