Exhibit (h)(4)

May 1, 2005

IXIS Advisor Funds Trust I
IXIS Advisor Funds Trust II
IXIS Advisor Funds Trust III
399 Boylston Street
Boston, MA 02116

Re: Fee Waiver/Expense Reimbursement

Ladies and Gentlemen:

     IXIS Asset Management Advisors, L.P. notifies you that it will waive its
management fee (and, to the extent necessary, bear other expenses of the Funds
listed below) through the dates listed below to the extent that expenses of each
class of a Fund, exclusive of brokerage, interest, taxes and deferred
organizational and extraordinary expenses, would exceed the following annual
rates:

Name of Fund                                         Expense Cap
------------                                         -----------

May 1, 2005 through April 30, 2006:

   Harris Associates Focused Value Fund      1.70% for Class A shares
                                             2.45% for Class B shares
                                             2.45% for Class C shares

   Harris Associates Large Cap Value Fund    1.30% for Class A shares
                                             2.05% for Class B shares
                                             2.05% for Class C shares
                                             1.05% for Class Y shares

   CDC IXIS Moderate Diversified Portfolio   1.65% for Class A shares
                                             2.40% for Class C shares

January 31, 2005 through April 30, 2006:

   IXIS Equity Diversified Portfolio*        1.65% for Class A shares
                                             2.40% for Class C shares

     With respect to each Fund, IXIS Asset Management Advisors, L.P. shall be
permitted to recover expenses it has borne subsequent to the effective date of
this agreement (whether through reduction of its management fee or otherwise) in
later periods to the extent that a Fund's expenses fall below the annual rates
set forth above. Provided, however, that a Fund is not



obligated to pay any such deferred fees more than one year after the end of the
fiscal year in which the fee was deferred.

     During the periods covered by this letter agreement, the expense cap
arrangement set forth above for each of the Funds may only be modified by a
majority vote of the "non-interested" Trustees of the Trusts affected.

     For purposes of determining any such waiver or expense reimbursement,
expenses of the class of the Funds shall not reflect the application of balance
credits made available by the Funds' custodian or arrangements under which
broker-dealers that execute portfolio transactions for the Funds' agree to bear
some portion of Fund expenses.

     We understand and intend that you will rely on this undertaking in
preparing and filing the Registration Statements on Form N-1A for the above
referenced Funds with the Securities and Exchange Commission, in accruing each
Fund's expenses for purposes of calculating its net asset value per share and
for other purposes permitted under Form N-1A and/or the Investment Company Act
of 1940, as amended, and expressly permit you to do so.

                                     IXIS Asset Management Advisors, L.P.


                                           By: /s/ Coleen Downs Dinneen
                                               ---------------------------------
                                               Coleen Downs Dinneen

                                           Title: Senior Vice President, General
                                                  Counsel, Secretary & Clerk