N.H. Rev. Stat. § 12-G:22

The authority, when authorized by the board, may issue refunding bonds for the purpose of paying any bonds issued under the provisions of RSA 12-G:17-28 at or prior to maturity or upon acceleration or redemption. Refunding bonds may be issued at such times prior to the maturity or redemption of the bonds being refunded as the board may determine. The refunding bonds may be issued in sufficient amounts to pay or provide the principal of the bonds being refunded, together with any redemption premium thereon, any interest accrued or to accrue to the date of payment of such bonds, the expenses of issue of the refunding bonds, the expenses of redeeming the bonds being refunded, and such reserves for debt service or other expenses from the proceeds of such refunding bonds as may be required by a security document securing the bonds. The authorization and issue of refunding bonds, the maturities and other details thereof, the security therefor, the rights of the holders thereof, and the rights, duties, and obligations of the authority in respect to the same shall be governed by the provisions of RSA 12-G:17-28 relating to the issue of bonds other than refunding bonds insofar as the same may be applicable.