Tex. Gov't Code § 1207.082

An issuer may issue refunding bonds to be exchanged under this subchapter to refund part of an outstanding issue of bonds, notes, or other obligations only if the issuer demonstrates to the attorney general at the time of the refunding that, based on then current conditions, the issuer will have adequate resources available at the times required to provide for the payment of the unrefunded part of the outstanding issue when due.