Cal. Streets and Highways Code § 31165

Any funding or refunding bonds may be issued in a principal amount sufficient to provide funds for: (a) The payment of the bonds to be funded or refunded thereby. (b) All expenses incidental to the calling, retiring, or payment of the outstanding bonds and the issuance of the funding or refunding bonds, including the difference in amount between the par value of the funding or refunding bonds and any amount less than par for which they may be sold. (c) Any amount necessary to be made available for the payment of interest upon the funding or refunding bonds from the date of their sale to the date of maturity or payment of the bonds to be funded or refunded out of the proceeds of the sale, or the date upon which the bonds to be funded or refunded will be paid pursuant to the call thereof or agreement with the holders thereof. (d) The premium, if any, necessary to be paid in order to call or retire the outstanding bonds.