Document:

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                                                                    EXHIBIT 4.05

                    Certificate Of Trust of AmerUs Capital IV

         This Certificate of Trust of AmerUs Capital IV (the "Trust"), is being
duly executed and filed by the undersigned, as trustee, to form a statutory
trust under the Delaware Statutory Trust Act (12 Del. C. Section 3801 et seq.)
(the "Act").

         1.       Name. The name of the statutory trust formed hereby is AmerUs
Capital IV.

         2.       Delaware Trustee. The name and business address of the trustee
of the Trust with its principal place of business in the State of Delaware is
The Bank of New York (Delaware), 502 White Clay Center, Route 273, Newark,
Delaware 19711, Attention: Corporate Trust Administration.

         3.       Effective Date. This Certificate of Trust shall be effective
upon filing with the Secretary of State of the State of Delaware.

         IN WITNESS WHEREOF, the undersigned, being the sole trustee of the
Trust, has executed this Certificate of Trust in accordance with Section 3811 of
the Act.

                                       The Bank of New York (Delaware),
                                       as Delaware Trustee

                                       By: /s/ Kristine Gullo
                                           --------------------------
                                           Name:   Kristine Gullo
                                           Title:  Vice President<PAGE>

                                                                    Exhibit 4.06

                                 TRUST AGREEMENT

      This TRUST AGREEMENT, dated as of July 12th, 2005, between AmerUs Group
Co., an Iowa corporation, as "Depositor" and The Bank of New York (Delaware) a
Delaware banking corporation as "Trustee". The Depositor and the Trustee hereby
agree as follows:

      1. The trust created hereby shall be known as AmerUs Capital IV, in which
name the Trustee, or the Depositor to the extent provided herein, may conduct
the business of the Trust, make and execute contracts, and sue and be sued.

      2. The Depositor hereby assigns, transfers, conveys and sets over to the
Trustee the sum of $10. The Trustee hereby acknowledges receipt of such amount
in trust from the Depositor, which amount shall constitute the initial trust
estate. The Trustee hereby declares that it will hold the trust estate in trust
for the Depositor. It is the intention of the parties hereto that the Trust
created hereby constitute a statutory trust under Chapter 38 of Title 12 of the
Delaware Code, 12 Del. C. Section 3801 et seq. (the "Statutory Trust Act"), and
that this document constitutes the governing instrument of the Trust. The
Trustee is hereby authorized and directed to execute and file a certificate of
trust with the Delaware Secretary of State in accordance with the provisions of
the Statutory Trust Act.

      3. The Depositor and the Trustee will enter into an amended and restated
Trust Agreement, satisfactory to each such party and substantially in the form
included as an exhibit to the 1933 Act Registration Statement (as defined
below), to provide for the contemplated operation of the Trust created hereby
and the issuance of the Preferred Securities and Common Securities referred to
therein. Prior to the execution and delivery of such amended and restated Trust
Agreement, the Trustee shall not have any duty or obligation hereunder or with
respect to the trust estate, and the Depositor shall take or cause to be taken
any action as may be required to obtain any licenses, consents or approvals
required by applicable law or otherwise. Notwithstanding the foregoing, the
Trustee may take all actions requested by the Depositor in writing which the
Depositor deems necessary, convenient or incidental to effect the transactions
contemplated herein. Except as otherwise expressly required by Section 2 herein,
the Trustee shall not have any duty or obligation under or in connection with
this Trust Agreement or any document contemplated hereby, including, without
limitation, with respect to the administration of the Trust, and no implied
duties or obligations shall be inferred from or read into this Trust Agreement
against or with respect to the Trustee. The Trustee has no duty or obligation to
supervise or monitor the performance of, or compliance with this Trust
Agreement, by the Depositor or any other beneficiaries, any agents or
attorneys-in-fact of the Depositor, or any other trustee of the Trust. The
Trustee shall not be liable for the acts or omissions of the Depositor or any
other beneficiaries, any agents or attorneys-in-fact of the Depositor, or any
other trustee of the Trust nor shall the Trustee be liable for any act or
omission by it in good faith in accordance with the directions of the Depositor.
The right of the Trustee to perform any discretionary act enumerated herein
shall not be construed as a duty. The Trustee accepts the Trust hereby created
and agrees to perform its duties hereunder with respect to the same but only

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upon the terms of this Trust Agreement. The Trustee shall not be personally
liable under any circumstances, except for its own willful misconduct or
negligence. In particular, but not by way of limitation:

            (a) The Trustee shall not be personally liable for any error of
      judgment made in good faith and in the absence of negligence by an officer
      or employee of the Trustee;

            (b) No provision of this Trust Agreement shall require the Trustee
      to expend or risk its personal funds or otherwise incur any financial
      liability in the performance of its rights or duties hereunder, if the
      Trustee shall have reasonable grounds for believing that repayment of such
      funds or adequate indemnity against such risk or liability is not
      reasonably assured or provided to it;

            (c) Under no circumstance shall the Trustee be personally liable for
      any representation, warranty, covenant or indebtedness of the Trust;

            (d) The Trustee shall not be personally responsible for or in
      respect of the genuineness, form or value of the Trust property, the
      validity or sufficiency of this Trust Agreement or for the due execution
      hereof by the Depositor;

            (e) All funds deposited with the Trustee hereunder may be held in a
      non-interest bearing trust account and the Trustee shall not be liable for
      any interest thereon or for any loss as a result of the investment thereof
      at the direction of the Depositor; and

            (f) To the extent that, at law or in equity, the Trustee has duties
      and liabilities relating to the Depositor or the Trust, the Depositor
      agrees that such duties and liabilities are replaced by the terms of this
      Trust Agreement.

      4. The Depositor is hereby authorized, (i) to file with the Securities and
Exchange Commission (the "Commission") and execute, in each case on behalf of
the Trust, (a) the Registration Statement on Form S-3 (the "1933 Act
Registration Statement"), including any pre-effective or post-effective
amendments to such 1933 Act Registration Statement (including the prospectus and
the exhibits contained therein), relating to the registration under the
Securities Act of 1933, as amended, of the Preferred Securities of the Trust and
certain other securities and (b) a Registration Statement on Form 8-A (the "1934
Act Registration Statement") (including all pre-effective and post-effective
amendments thereto) relating to the registration of the Preferred Securities of
the Trust under Section 12(b) of the Securities Exchange Act of 1934, as
amended; (ii) to file with the New York Stock Exchange (the "Exchange") and
execute on behalf of the Trust a listing application and all other applications,
statements, certificates, agreements and other instruments as shall be necessary
or desirable to cause the Preferred Securities to be listed on the Exchange;
(iii) to file and execute on behalf of the Trust such applications, reports,
surety bonds, irrevocable consents, appointments of attorney for service of
process and other papers and documents as shall be necessary or desirable to
register the Preferred Securities under the securities or "Blue Sky" laws, and
to obtain any permits under the insurance laws of such jurisdictions as the
Depositor, on behalf of the Trust, may deem necessary or desirable and (iv) to
execute on behalf of the Trust one or more Underwriting Agreements with one or
more underwriters relating to the offering of the Preferred Securities. In the
event that any filing

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referred to in clauses (i), (ii) and (iii) above is required by the rules and
regulations of the Commission, the Exchange or state securities or blue sky
laws, to be executed on behalf of the Trust by a Trustee, the Depositor and any
Trustee appointed pursuant to Section 8 hereof are hereby authorized to join in
any such filing and to execute on behalf of the Trust any and all of the
foregoing. In connection with all of the foregoing, the Depositor hereby
constitutes and appoints Thomas C. Godlasky, Melinda S. Urion and James A.
Smallenberger, and each of them, as its true and lawful attorneys-in-fact and
agents, with full power of substitution and resubstitution, for the Depositor or
in the Depositor's name, place and stead, in any and all capacities, to sign any
and all amendments (including post-effective amendments) to the 1933 Act
Registration Statement and the 1934 Act Registration Statement and to file the
same, with all exhibits thereto, and other documents in connection therewith,
with the Commission, granting unto said attorneys-in-fact and agents full power
and authority to do and perform each and every act and thing requisite and
necessary to be done in connection therewith, as fully to all intents and
purposes as the Depositor might or could do in person, hereby ratifying and
confirming all that said attorneys-in-fact and agents or any of them, or their
respective substitute or substitutes, shall do or cause to be done by virtue
hereof.

      5. The Trustee is authorized to take such action or refrain from taking
such action under this Trust Agreement as it may be directed in writing by the
Depositor from time to time; provided, however, that the Trustee shall not be
required to take or refrain from taking any such action if it shall have
determined, or shall have been advised by counsel, that such performance is
likely to involve the Trustee in personal liability or is contrary to the terms
of this Trust Agreement or of any document contemplated hereby to which the
Trust or the Trustee is a party or is otherwise contrary to law. If at any time
the Trustee determines that it requires or desires guidance regarding the
application of any provision of this Trust Agreement or any other document, or
regarding compliance with any direction it received hereunder, then the Trustee
may deliver a notice to the Depositor requesting written instructions as to the
course of action desired by the Depositor, and such instructions by or on behalf
of the Depositor shall constitute full and complete authorization and protection
for actions taken and other performance by the Trustee in reliance thereon.
Until the Trustee has received such instructions after delivering such notice,
it may refrain from taking any action with respect to the matters described in
such notice.

      6. The Depositor hereby agrees to (i) reimburse the Trustee for all
reasonable expenses (including reasonable fees and expenses of counsel and other
experts), (ii) indemnify, defend and hold harmless the Trustee and the officers,
directors, employees and agents of the Trustee (collectively, including the
Trustee in its individual capacity, the "Indemnified Persons") from and against
any and all losses, damages, liabilities, claims, actions, suits, costs,
expenses, disbursements (including the reasonable fees and expenses of counsel),
taxes and penalties of any kind and nature whatsoever (collectively,
"Expenses"), to the extent that such Expenses arise out of or are imposed upon
or asserted at any time against such Indemnified Persons with respect to the
performance of this Trust Agreement, the creation, operation, administration or
termination of the Trust, or the transactions contemplated hereby; provided,
however, that the Depositor shall not be required to indemnify an Indemnified
Person for Expenses to the extent such Expenses result from the willful
misconduct, bad faith or negligence of such Indemnified Person, and (iii)
advance to each such Indemnified Person Expenses (including reasonable fees and
expenses of counsel) incurred by such Indemnified Person, in defending any
claim, demand, action, suit or proceeding prior to the final disposition of such
claim, demand, action, suit or

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proceeding upon receipt by the Depositor of an undertaking, by or on behalf of
such Indemnified Person, to repay such amount if it shall be determined that
such Indemnified Person is not entitled to be indemnified therefor under this
Section 6. The obligations of the Depositor under this Section 6 shall survive
the resignation or removal of any Trustee, shall survive the termination of this
Trust Agreement, except by amendment and restatement of this Trust Agreement,
and shall survive the transfer by the Depositor of any or all of its interest in
the Trust.

      7. This Trust Agreement may be executed in one or more counterparts, each
of which shall be deemed an original but all of which together shall constitute
one and the same instrument.

      8. The number of Trustees initially shall be one (1) and thereafter the
number of Trustees shall be such number as shall be fixed from time to time by a
written instrument signed by the Depositor which may increase or decrease the
number of Trustees; provided, however, that to the extent required by the
Statutory Trust Act, one Trustee shall either be a natural person who is a
resident of the State of Delaware or, if not a natural person, an entity which
has its principal place of business in the State of Delaware and otherwise meets
the requirements of applicable Delaware law. Subject to the foregoing, the
Depositor is entitled to appoint or remove without cause any Trustee at any
time. The Trustee may resign upon thirty days' prior notice to the Depositor. If
no successor has been appointed within such thirty day period, the Trustee may,
at the expense of the Depositor, petition a court of competent jurisdiction to
appoint a successor trustee.

      9. This Trust Agreement represents the entire agreement between the
parties hereto with respect to the subject matter hereof, and supersedes all
prior agreements and understandings between the parties, whether written or
oral.

      10. This Trust Agreement shall be governed by and construed in accordance
with the laws of the State of Delaware, without reference to its conflict of law
provisions, and the obligations, rights and remedies of the parties hereunder
shall be determined in accordance with such laws, PROVIDED, HOWEVER, THAT THERE
SHALL NOT BE APPLICABLE TO THE PARTIES HEREUNDER OR THIS TRUST AGREEMENT ANY
PROVISION OF THE LAWS (COMMON OR STATUTORY) OF THE STATE OF DELAWARE PERTAINING
TO TRUSTS THAT RELATE TO OR REGULATE, IN A MANNER INCONSISTENT WITH THE TERMS
HEREOF, (A) THE FILING WITH ANY COURT OR GOVERNMENTAL BODY OR AGENCY OF TRUSTEE
ACCOUNTS OR SCHEDULES OF TRUSTEE FEES AND CHARGES, (B) AFFIRMATIVE REQUIREMENTS
TO POST BONDS FOR TRUSTEES, OFFICERS, AGENTS OR EMPLOYEES OF A TRUST, (C) THE
NECESSITY FOR OBTAINING COURT OR OTHER GOVERNMENTAL APPROVAL CONCERNING THE
ACQUISITION, HOLDING OR DISPOSITION OF REAL OR PERSONAL PROPERTY, (D) FEES OR
OTHER SUMS PAYABLE TO TRUSTEES, OFFICERS, AGENTS OR EMPLOYEES OF A TRUST, (E)
THE ALLOCATION OF RECEIPTS AND EXPENDITURES TO INCOME OR PRINCIPAL, (F)
RESTRICTIONS OR LIMITATIONS ON THE PERMISSIBLE NATURE, AMOUNT OR CONCENTRATION
OF TRUST INVESTMENTS OR REQUIREMENTS RELATING TO THE TITLING, STORAGE OR OTHER
MANNER OF HOLDING OR INVESTING TRUST ASSETS OR (G) THE ESTABLISHMENT OF

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FIDUCIARY OR OTHER STANDARDS OF RESPONSIBILITY OR LIMITATIONS ON THE ACTS OR
POWERS OF TRUSTEES THAT ARE INCONSISTENT WITH THE LIMITATIONS OR AUTHORITIES AND
POWERS OF THE TRUSTEES HEREUNDER AS SET FORTH OR REFERENCED IN THIS AGREEMENT.
SECTION 3540 OF TITLE 12 OF THE DELAWARE CODE SHALL NOT APPLY TO THE TRUST.

      11. This Trust Agreement may be executed in two or more counterparts, each
of which shall be an original, but all such counterparts shall together
constitute one and the same agreement.

      12. This Trust Agreement may be amended and restated by the parties hereto
as necessary to provide for the operation of the Trust; provided, however, that
the Trustee shall not be required to enter into any amendment hereto which
adversely affects the rights, duties or immunities of the Trustee.

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      IN WITNESS WHEREOF, the parties hereto have caused this Trust Agreement to
be duly executed as of the day and year first above written.

                                        AMERUS GROUP CO.,
                                        as Depositor

                                        By: /s/ Thomas C. Godlasky
                                           ----------------------------
                                            Name: Thomas C. Godlasky
                                            Title: President and Chief Operating
                                                   Officer

                                        By: /s/ Melinda S. Urion
                                           ----------------------------
                                            Name: Melinda S. Urion
                                            Title: Executive Vice President,
                                                   Chief Financial Officer and
                                                   Treasurer

                                        THE BANK OF NEW YORK (DELAWARE),
                                        as Trustee

                                        By: /s/ Kristine Gullo
                                           ----------------------------
                                            Name: Kristine Gullo
                                            Title: Vice President

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