(2) In connection with the issuance of bonds for the purpose of furthering programs described in this title, the agency is authorized to covenant and consent that the interest on any of its bonds, notes or other obligations shall be includable, under the United States Internal Revenue Code of 1986, as amended or any subsequent corresponding internal revenue law of the United States, in the gross income of the holders of the bonds to the same extent and in the same manner that the interest on bills, bonds, notes or other obligations of the United States is includable in the gross income of the holders thereof under said Internal Revenue Code or any such subsequent law. Pursuant to this subdivision, the agency shall not issue bonds, notes or other obligations in an aggregate principal amount exceeding one billion dollars, excluding from such limitation bonds, notes or other obligations issued to refund outstanding bonds, notes or other obligations. No such bond, note or other obligation shall be issued by the agency on or after July twenty-third, two thousand twenty-one, excluding bonds, notes or other obligations issued to refund outstanding bonds, notes or other obligations and no mortgages shall be purchased with the proceeds of such bonds, notes or other obligations after such date. The board of directors of the agency shall establish program guidelines for purposes of bonds, notes or other obligations issued pursuant to this subdivision. The board of directors shall establish from time to time maximum income limits of persons eligible to receive mortgages financed by bonds, notes or other obligations issued pursuant to this subdivision, which income limits with respect to one-third of the total principal amount of mortgages authorized to be so financed shall not exceed one hundred twenty-five percent of the latest maximum income limits permitted under the Internal Revenue Code of 1986, as amended, for mortgagors financed by mortgage revenue bonds, with respect to one-third of such principal amount authorized to be so financed, shall not exceed one hundred thirty-five percent of such income limits, and with respect to one-third of such principal amount authorized to be so financed, shall not exceed one hundred fifty percent of such limits, provided that notwithstanding the foregoing, the maximum income limits of persons eligible to receive mortgages financed by the agency under its neighborhood revitalization program (and any successor program) shall not exceed one hundred fifty percent of the latest maximum income limits permitted under the Internal Revenue Code of 1986, as amended, for mortgagors financed by mortgage revenue bonds.

(3) The fixing of the statutory maximums in this section shall not be construed as constituting a contract between the agency and the holders of its bonds or notes that additional bonds and notes may not be issued subsequently by the agency in the event that such statutory maximums shall subsequently be increased by law.