55 Pa. Stat. § 697.14
The effectuation of the authorized purposes of the authority created under this act shall and will be in all respects for the benefit of the people of this Commonwealth, for the increase of their commerce and prosperity, and for the improvement of their health and living conditions; and since the authority will be performing essential government functions in effectuating such purposes, the authority shall not be required to pay any taxes or assessments upon any property acquired or used by it for such purposes, or fees, bridge tolls or other charges imposed or authorized to be imposed by virtue of any law of the Commonwealth, except vehicle registration fees, liquid fuels taxes, fuel use taxes, gross receipts taxes imposed as an excise on the use of public highways, and tolls imposed by the Pennsylvania Turnpike Commission. The authority shall have the power to make payments in lieu of taxes or special assessments. The bonds issued by the authority, and their transfer and the income therefrom, including any profits made on the sale thereof, shall be free from State and local taxation within this Commonwealth, other than gift, estate, succession or inheritance taxes.
55 P.S. § 697.14