72 Pa. Stat. § 5570c
This act shall be construed to apply to all such taxes whether or not liens for such taxes had been returned for nonpayment, or have been filed in the office of the prothonotary of the county, or proceedings for the collection of such taxes have been instituted in any court in said county, or where real property has been sold to a county, city, borough, town, township, school district or poor district at a tax sale or on a tax lien, and the period of redemption has not expired; but this act shall not be construed to apply to cases where real property has been sold other than to a county, city, borough, town, township, school district or poor district at a tax sale or on a tax lien, and where the period of redemption has not expired. The taxpayer shall be liable for the payment of all costs incurred, except the solicitor's fees, where liens for such taxes have been returned for nonpayment, or have been filed in the office of the prothonotary, or proceedings for the collection thereof have been instituted in any court.
72 P.S. § 5570c