72 Pa. Stat. § 8907-B
If and to the extent that the contracting authority pledges amounts required to be transferred to the fund of the contracting authority under section 1904-B for the payment of bonds issued by the contracting authority, until all bonds secured by the pledge of the contracting authority, together with the interest on the bonds, are fully paid or provided for, the Commonwealth pledges to and agrees with any person, firm, corporation or government agency, whether in this Commonwealth or elsewhere, and to and with any Federal agency subscribing to or acquiring the bonds issued by the contracting authority that the Commonwealth itself will not, nor will it authorize any government entity to, abolish or reduce the size of the neighborhood improvement zone; to amend or repeal section 1904- B(a.1), (b) or (d); to limit or alter the rights vested in the contracting authority in a manner inconsistent with the obligations of the contracting authority with respect to the bonds issued by the contracting authority; or to otherwise impair revenues to be paid under this article to the contracting authority necessary to pay debt service on bonds. Nothing in this section shall limit the authority of the Commonwealth or any government entity to change the rate, tax bases or any subject of any specific tax or repealing or enacting any tax.
72 P.S. § 8907-B