53 Pa. Stat. § 30903
The lands sold under this act may be redeemed by the owner or by any one interested in said lands, at any time within one year such sale, by the payment to the city treasurer of the full amount which the purchaser paid to said treasurer for taxes and costs and ten percent in addition thereto, and when the sale has been made for less than the taxes and costs, the party redeeming shall pay to said treasurer the balance of taxes and costs which were not made by the sale of the said property. In case there are any city taxes levied, either before or after the said sale, which remain unpaid, the person redeeming shall pay the same and all penalties, interest and lien costs thereon, and in case the purchaser has paid any taxes, of any kind whatsoever, assessed and levied against said property, the same shall be reimbursed to said purchaser before any redemption shall take effect. The said treasurer shall keep in his office a book or schedule in which he shall enter all the sales made by him, giving a description of each property sold, the name of the person as the owner thereof, as the same appears upon the duplicate or has been returned to him, the time of sale and the price at which sold, together with the cost. Each respective city shall have the right to bid at any such sale, the amount of taxes and costs and, if necessary, purchase such lands.
53 P.S. § 30903