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                                                                    Exhibit 4.12

                    AGREEMENT AS TO EXPENSES AND LIABILITIES

     AGREEMENT AS TO EXPENSES AND LIABILITIES (this "Agreement") dated as of
[_______], between AGL RESOURCES, INC., a Georgia corporation (the "Guarantor"),
AGL CAPITAL CORPORATION, a Nevada corporation (the "Company") and AGL CAPITAL
TRUST III, a Delaware business trust (the "Trust").

                                    RECITALS

     WHEREAS, the Trust intends to issue its common securities (the "Common
Securities") to, and receive Debentures from, the Company and to issue and sell
[ ]% Trust Preferred Securities (the "Preferred Securities") with such powers,
preferences and special rights and restrictions as are set forth in the Amended
and Restated Trust Agreement dated [______], as the same may be amended from
time to time (the "Trust Agreement");

     WHEREAS, the Company shall directly or indirectly own all of the Common
Securities of the Trust and shall issue the Debentures;

     NOW, THEREFORE, in consideration of the purchase by each holder of the
Preferred Securities, which purchase the Guarantor and the Company hereby agree
shall benefit the Guarantor and the Company and which purchase the Guarantor and
the Company acknowledge shall be made in reliance upon the execution and
delivery of this Agreement, the Guarantor, the Company, including in its
capacity as holder of the Common Securities, and the Trust hereby agree as
follows:

                                    ARTICLE I

     Section 1.1 Guarantee by the Guarantor. Subject to the terms and conditions
hereof, the Guarantor hereby irrevocably and unconditionally guarantees to each
person or entity to whom the Trust is now or hereafter becomes indebted or
liable (the "Beneficiaries") the full payment when and as due, of any and all
Obligations (as hereinafter defined) to such Beneficiaries. As used herein,
"Obligations" means any costs, expenses or liabilities of the Trust other than
obligations of the Trust to pay to holders of any Preferred Securities or other
similar interests in the Trust the amounts due such holders pursuant to the
terms of the Preferred Securities or such other similar interests, as the case
may be. This Agreement is intended to be for the benefit of, and to be
enforceable by, all such Beneficiaries, whether or not such Beneficiaries have
received notice hereof.

     Section 1.2 Term of Agreement. This Agreement shall terminate and be of
no further force and effect upon the later of (a) the date on which full payment
has been made of all amounts payable to all holders of all the Preferred
Securities (whether upon redemption, liquidation, exchange or otherwise); and
(b) the date on which there are no Beneficiaries remaining; provided, however,
that this Agreement shall continue to be effective or shall be reinstated, as
the case may be, if at any time any holder of Preferred Securities or any
Beneficiary must restore payment of any sums paid under the Preferred
Securities, under any obligation, under the Trust Preferred Securities Guarantee
Agreement dated the date hereof

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between the Guarantor and The Bank of New York, as guarantee trustee, or under
this Agreement for any reason whatsoever. This Agreement is continuing,
irrevocable, unconditional and absolute.

     Section 1.3 Waiver of Notice. The Guarantor and the Company hereby waive
notice of acceptance of this Agreement and of any obligation to which it applies
or may apply, and the Guarantor and the Company hereby waive presentment, demand
for payment, protest, notice of nonpayment, notice of dishonor, notice of
redemption and all other notices and demands.

     Section 1.4 No Impairment. The obligations, covenants, agreements and
duties of the Guarantor and the Company under this Agreement shall in no way be
affected or impaired by reason of the happening from time to time of any of the
following:

     (a)  the extension of time for the payment by the Trust of all or any
portion of the obligations or for the performance of any other obligation under,
arising out of, or in connection with, the obligations;

     (b)  any failure, omission, delay or lack of diligence on the part of the
Beneficiaries to enforce, assert or exercise any right, privilege, power or
remedy conferred on the Beneficiaries with respect to the obligations or any
action on the part of the Trust granting indulgence or extension of any kind; or

     (c)  the voluntary or involuntary liquidation, dissolution, sale of any
collateral, receivership, insolvency, bankruptcy, assignment for the benefit of
creditors, reorganization, arrangement composition or readjustment of debt of,
or other similar proceedings affecting, the Trust or any of the assets of the
Trust.

     There shall be no obligation of the Beneficiaries to give notice to, or
obtain the consent of, the Company with respect to the happening of any of the
foregoing.

     Section 1.5 Enforcement. A Beneficiary may enforce this Agreement directly
against the Guarantor and the Company, and the Company waives any right or
remedy to require that any action be brought against the Trust or any other
person or entity before proceeding against the Guarantor and the Company.

                                  ARTICLE II

     Section 2.1 Binding Effect. All guarantees and agreements contained in this
Agreement shall bind the successors, assigns, receivers, trustees and
representatives of the Guarantor and the Company and shall inure to the benefit
of the Beneficiaries.

     Section 2.2 Amendment. So long as there remains any Beneficiary or any
Preferred Securities of any series are outstanding, this Agreement shall not be
modified or amended in any manner adverse to such Beneficiary or to the holders
of the Preferred Securities.

     Section 2.3 Notices. Any notice, request or other communication required or
permitted to be given hereunder shall be given in writing by delivering the same
by facsimile transmission

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(confirmed by mail), telex, or by registered or certified mail, addressed as
follows (and if so given, shall be deemed given when mailed or upon receipt of
an answer back, if sent by telex):

                             AGL RESOURCES INC.
                             817 West Peachtree Street, N.W.
                             Atlanta, Georgia 30308
                             Attn: Richard T. O'Brien

                             AGL CAPITAL CORPORATION
                             2325-B Renaissance Drive
                             Las Vegas, Nevada 89119
                             Attn: Paul R. Shlanta

                             AGL CAPITAL TRUST III
                             2325-B Renaissance Drive
                             Las Vegas, Nevada 89119
                             Attn: Paul R. Shlanta

     Section 2.4 Governing Law. This agreement shall be governed by and
construed and interpreted in accordance with the laws of the State of Georgia
(without regard to conflict of laws principles).

     THIS AGREEMENT is executed as of the day and year first above written.

                                       AGL RESOURCES, Inc.


                                       By: ___________________________________
                                           Richard T. O'Brien
                                           Executive Vice President and Chief
                                           Financial Officer

                                       AGL CAPITAL CORPORATION


                                       By: ___________________________________
                                           Paul R. Shlanta, President

                                       AGL Capital TRUST III


                                       By: ___________________________________
                                           Paul R. Shlanta, Administrative
                                           Trustee

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