53 Pa. Stat. § 56709.1
If in any township there is any construction of a building or buildings not otherwise exempt as a dwelling after January first of any year and the building is not included in the tax duplicate of the township, the county assessment office shall, upon the request of the board of commissioners, direct the assessor in the county assessment office to inspect and reassess, subject to the right of appeal and adjustment by statute, all taxable property in the township to which major improvements have been made after January first of any year and to give notice of the reassessments within ten days to the authority responsible for assessments, the township and the property owner. The real property shall be added to the duplicate and shall be taxable for township purposes at the reassessed valuation for that proportionate part of the fiscal year of the township remaining after the property was improved. Any improvement made during the month shall be computed as having been made on the first day of the month. A certified copy of the additions or revisions to the duplicate shall be furnished by the board of township commissioners to the township tax collector, together with the board's warrant for collection of the same, and within ten days the township tax collector shall notify the owner of the property of the taxes due the township.
53 P.S. § 56709.1