72 Pa. Stat. § 5971d
All taxes unpaid and so returned and docketed, as aforesaid, shall be a first lien, subject as hereinafter stated, on said real estate liable for the payment thereof, together with all charges, interest, expenses and fees added thereto for failure to pay promptly; and such liens shall have priority to and be fully paid and satisfied out of the proceeds of any judicial sale of said property before any mortgage, obligation, claim, lien or estate with which said property may have or shall become charged or for which it may become liable, save and except only the costs of the sale and of the writ upon which it is made, and liens in favor of the Commonwealth of Pennsylvania, which shall have priority to such tax liens. All taxes returned under this or any previous statute supplied hereby shall be first liens until sold, as hereinafter provided, or unless sooner discharged.
72 P.S. § 5971d