Ala. Code § 16-60-92

The authority may from time to time issue refunding bonds for the purpose of refunding any matured or unmatured bonds of the authority then outstanding. Any premium that may be necessary to redeem or retire the bonds to be refunded and all expenses of issuing the refunding bonds may be paid out of the proceeds from the sale of the refunding bonds. The principal of the refunding bonds shall not exceed the principal of the bonds to be refunded plus any such premium and expenses. If the total of the principal and interest maturing with respect to any refunding bonds, during each fiscal year in which any of the bonds secured on a parity with the bonds to be refunded have a stated maturity, does not exceed the total of the principal and interest that would have matured during the same fiscal year on the said bonds to be refunded, then the refunding bonds shall be subrogated and entitled to all priorities, rights and pledges to which the bonds refunded thereby were entitled. Except in cases covered by the preceding sentence, all pledges for the benefit of refunding bonds shall be subject to pledges theretofore made for the benefit of all bonds of the authority then outstanding. All the provisions of Section 16-60-91 shall apply to the refunding bonds issued under this article.