Tex. Education Code § 66.22: REFUNDING BONDS AND NOTES.

Any bonds or notes issued pursuant to the constitutional provisions described in Section 66.21 of this code, or issued pursuant to this subchapter, may be refunded by the governing board which issued the bonds or notes, upon such terms and conditions, including interest rates and maturities, as may be determined by that board, provided that such terms and conditions shall not be inconsistent with the applicable constitutional provisions. Any such bonds or notes may be so refunded by the issuance of refunding bonds or notes, either to be exchanged for the bonds or notes being refunded and cancelled, or to be sold, with the proceeds to be used for the redemption and cancellation of the bonds or notes being refunded.

Acts 1971, 62nd Leg., p. 3150, ch. 1024, art. 1, Sec. 1, eff. Sept. 1, 1971.