53 Pa. Stat. § 25895
They shall triennially make a valuation for all purposes of municipal taxation, and shall have the power to administer oaths. They shall have the power to make a new assessment in any ward or wards they deem necessary in any subsequent year, other than triennial years, in the manner prescribed by law for the triennial assessment. Any property owners shall have the right to be heard by the full board, sitting as a board of revision, on appeal from any valuation. The assessment, as aforesaid, shall remain the lawful assessment for purposes of city taxation until the next assessment. Nothing herein contained shall be construed to repeal the act of July nine, one thousand eight hundred and ninety-seven, providing for the classification of real estate and other property for purposes of taxation, and for the election of assessors and prescribing the duties thereof, in cities of the second class, except as far as the same may be inconsistent herewith.
The councils shall, by ordinance, make all further needful rules and regulations for the government of this department.
53 P.S. § 25895