ALLIANT ENERGY CORPORATION
                               401(k) SAVINGS PLAN






               (As Amended and Restated Effective January 1, 2002)


                                TABLE OF CONTENTS
                                -----------------

                                                                            PAGE
                                                                            ----

ARTICLE I. INTRODUCTION........................................................1
     1.1      Establishment and Purpose........................................1
     1.2      Legal Requirements...............................................1
     1.3      Absence of Guarantee.............................................1
     1.4      Employment Rights................................................1
     1.5      Litigation by Participants.......................................1
     1.6      Controlling Law..................................................1
     1.7      Merger or Consolidation of Plan and Trust Fund...................2
     1.8      Gender and Number................................................2
     1.9      Participating Groups and Schedules...............................2
     1.10     Effective Dates..................................................2

ARTICLE II. DEFINITIONS........................................................3
     2.1      Account..........................................................3
     2.2      Affiliated Company...............................................3
     2.3      Alliant Common Stock Fund........................................3
     2.4      Alliant ESOP Fund................................................3
     2.5      Alliant Non-ESOP Fund............................................3
     2.6      Beneficiary......................................................3
     2.7      Code.............................................................4
     2.8      Committee........................................................4
     2.9      Company..........................................................4
     2.10     Company  Contributions...........................................4
     2.11     Compensation.....................................................4
     2.12     Corporation......................................................5
     2.13     Deferred Cash Contributions......................................5
     2.14     Disability.......................................................5
     2.15     Employee Pretax Account..........................................5
     2.16     Employer Contribution Account....................................5
     2.17     Employer Match A Account.........................................5
     2.18     Employer Match B Account.........................................5
     2.19     ERISA............................................................5
     2.20     Highly Compensated Employee......................................5
     2.21     Investment Funds.................................................5
     2.22     Participant......................................................6
     2.23     Participant Loan Fund............................................6
     2.24     Participating Group..............................................6
     2.25     Plan.............................................................6
     2.26     Plan Year........................................................6

                                       i

                                                                            PAGE
                                                                            ----

     2.27     Post-86 Aftertax Account.........................................6
     2.28     Pre-87 Aftertax Account..........................................6
     2.29     Prior Plan Monies Account........................................6
     2.30     Rollover Contributions...........................................6
     2.31     Rollover Contribution Account....................................6
     2.32     Schedule.........................................................6
     2.33     Spouse...........................................................6
     2.34     Trust Agreement..................................................6
     2.35     Trust Fund.......................................................6
     2.36     Trustee..........................................................7
     2.37     Valuation Date...................................................7

ARTICLE III. PARTICIPATION.....................................................8
     3.1      Eligibility Requirements.........................................8
     3.2      Participation Requirements.......................................8
     3.3      Duration of Participation........................................9
     3.4      Leased Employees.................................................9
     3.5      Collective Bargaining Unit Employees.............................9
     3.6      Nonresident Alien................................................9
     3.7      Common Law Employees.............................................9

ARTICLE IV. DEFERRED CASH CONTRIBUTIONS.......................................10
     4.1      Contribution (Payroll) Deduction................................10
     4.2      Age 50 Catch-Up Contributions...................................10
     4.3      Effect of Contribution (Payroll) Deduction......................11

ARTICLE V. CONTRIBUTIONS......................................................12
     5.1      Deferred Cash Contributions.....................................12
     5.2      Company Contributions...........................................12
     5.3      Actual Deferral Percentage......................................12
     5.4      Required Test and Adjustment....................................13
     5.5      Adjustment to Company Contribution Accounts.....................14
     5.6      Rollover Contributions..........................................16

ARTICLE VI. ACCOUNTS..........................................................17
     6.1      Valuation of Accounts...........................................17
     6.2      Allocation of Contributions and Withdrawals.....................17
     6.3      Allocation of Net Earnings or Losses............................17
     6.4      Allocation of Distributions.....................................17
     6.5      Limitations on Allocations......................................17

                                       ii

                                                                            PAGE
                                                                            ----

ARTICLE VII. INVESTMENT OF TRUST FUNDS........................................19
     7.1      Investment Funds................................................19
     7.2      Investment Elections............................................19
     7.3      Special Provisions Re: Common Stock of
               Alliant Energy Corporation.....................................20
     7.4      Loans...........................................................21

ARTICLE VIII. NONFORFEITURE OF BENEFITS.......................................24

ARTICLE IX. DISTRIBUTIONS.....................................................25
     9.1      Distributions as a Result of Termination or Disability..........25
     9.2      Direct Transfer of Eligible Rollover Distributions..............26
     9.3      Payments to Beneficiary.........................................27
     9.4      Provision Regarding Unpaid Loans................................27
     9.5      Participant's Interest Not Transferable.........................28
     9.6      Facility of Payment.............................................28

ARTICLE X. WITHDRAWALS DURING EMPLOYMENT......................................29
     10.1     Hardship Withdrawals............................................29
     10.2     Other In-Service Withdrawals....................................30

ARTICLE XI. ADMINISTRATION....................................................32
     11.1     Plan Administered by Committee..................................32
     11.2     Indemnity for Liability.........................................33
     11.3     Appeal from Denial of Claims....................................33
     11.4     USERRA Compliance...............................................34

ARTICLE XII. AMENDMENT AND TERMINATION........................................35
     12.1     Amendment.......................................................35
     12.2     Right to Terminate Plan.........................................35

ARTICLE XIII. TOP-HEAVY RESTRICTIONS..........................................36
     13.1     General.........................................................36
     13.2     Minimum Benefits................................................37

ARTICLE XIV. LEVERAGING.......................................................38
     14.1     Acquisition Loans...............................................38
     14.2     Loan Suspense Account...........................................38
     14.3     Restrictions on Allocations.....................................39
     14.4     Impact on Annual Additions Limitations..........................39
     14.5     Company Contributions...........................................40
     14.6     Excess Match....................................................40
     14.7     Nonterminable Rights............................................40

                                       iii

                                                                            PAGE
                                                                            ----

Schedule A....................................................................41

Schedule B....................................................................42

Schedule C....................................................................44

Schedule D....................................................................45



                                       iv

                            ARTICLE I. INTRODUCTION
                            -----------------------

1.1       Establishment and Purpose. Effective May 29, 1998 the Interstate Power
          Company 401(k) Plan and IES Industries Inc. Employee Savings Plan were
          merged into the Wisconsin Power and Light Company Employees'
          Retirement Savings Plan, with the merged plan renamed the Interstate
          Energy Corporation 401(k) Savings Plan. The Plan was renamed the
          Alliant Energy Corporation 401(k) Savings Plan effective June 30, 1999
          and was amended in several other respects prior to 2002. This
          restatement is effective January 1, 2002 and is intended (i) to
          satisfy applicable statutory and regulatory requirements, (ii) to
          implement an employee stock ownership plan as a portion of the Plan in
          order to make the Company eligible for the dividend deduction
          provisions of Code Section 404(k), and (iii) to implement certain
          other design changes. The purpose of the Plan is to encourage savings
          and to provide tax-effective compensation to eligible employees.

1.2       Legal Requirements. The Plan is intended to constitute both a
          qualified cash or deferred compensation arrangement within a profit
          sharing plan within the meaning of Code Sections 401(k) and 402(a)(8)
          and a stock bonus plan which is an employee stock ownership plan
          within the meaning of Code Sections 404(k) and 4975(e)(7). The Trust
          Agreement providing for the investment of contributions made hereunder
          and for the payment of benefits to Participants is intended to
          constitute a qualified trust within the meanings of Code Sections 401
          and 501(a).

1.3       Absence of Guarantee. Neither the Committee, the Trustee, the
          Corporation, nor the Company in any way guarantees the Trust Fund
          against loss or depreciation. The Company does not guarantee any
          payment to any person. The liability of the Company, the Trustee, the
          Corporation, and the Committee to make any payment under this Plan
          will be limited to the assets in the Trust Fund which are available
          for that purpose.

1.4       Employment Rights. The Plan shall not constitute a contract of
          employment with any employee. Participation in the Plan will not give
          any Participant the right to be retained in the employ of the Company,
          nor any right or claim to any distribution under the Plan, unless such
          claim has specifically accrued under the terms of the Plan.

1.5       Litigation by Participants. To the extent permitted by law, if a legal
          action begun against the Trustee, the Corporation, the Company, or the
          Committee by or on behalf of any person, results in a decision adverse
          to that person; or if a legal action arises because of conflicting
          claims to a Participant's Account(s), the cost and expense incurred by
          the Trustee, the Corporation, the Company, and the Committee of
          defending or participating in the action will be charged, to the
          extent permitted by law, to the sums, if any, which were involved in
          the action or were payable to the Participant or other person
          concerned.

1.6       Controlling Law. Except to the extent superseded by laws of the United
          States, the laws of Wisconsin shall be controlling in all matters
          relating to the Plan.

1.7       Merger or Consolidation of Plan and Trust Fund. Neither the Plan nor
          the Trust Fund may be merged or consolidated with, nor may its assets
          and liabilities be transferred to, any other plan or trust, unless
          each Participant would (if such plan then terminated) be entitled to a
          benefit immediately after the merger, consolidation or transfer which
          is equal to or greater than the benefit to which such Participant
          would have been entitled immediately before the merger, consolidation
          or transfer (if the Plan had then terminated).

1.8       Gender and Number. Where the context permits, words in the masculine
          gender shall include the feminine and neuter genders, the single shall
          include the plural, and the plural shall include the singular.

1.9       Participating Groups and Schedules. The eligible employees are
          comprised of a number of different Participating Groups. As a result
          of collective bargaining, prior plan benefits, and/or other factors,
          the substantive provisions vary between the Participating Groups and
          are reflected in both the basic text and the applicable Schedules with
          respect to applicable Accounts. In the event a Participant transfers
          from one Participating Group to another, except as otherwise provided,
          assets in a particular Account shall remain in such Account and be
          subject to the rules applicable for such Account.

1.10      Effective Dates. The USERRA rules in paragraph 11.4 shall be
          retroactively effective to December 12, 1994. The discrimination tests
          reflected in Sections 5.4 and 5.5 as they applied in the pre-2002
          document shall be retroactively amended to reflect that the "current
          year" method was utilized in 1998 for all groups except for the WPL
          bargaining group and in 2000 for all groups.

                                       2

                             ARTICLE II DEFINITIONS
                             ----------------------

As used in this Plan, the following terms shall have the meanings set forth
below, unless the context clearly indicates otherwise:

2.1       Account or Accounts means the record of a Participant's interest in
          the Plan, composed of the Employee Pretax Account, the Employer
          Contribution Account, the Employer Match A Account, the Employer Match
          B Account, the Pre-87 Aftertax Account, the Post-86 Aftertax Account,
          the Prior Plan Monies Account, and the Rollover Account.

2.2       Affiliated Company means any corporation or other entity which is
          treated as a single employer with the Corporation pursuant to Code
          Section 414(b), (c), (m) or (o), including the Corporation and any
          other Company.

2.3       Alliant Common Stock Fund means the Investment Fund described in
          paragraph 7.3. It has two subaccounts, the Alliant ESOP Fund and the
          Alliant Non-ESOP Fund.

2.4       Alliant ESOP Fund means the Alliant Energy Corporation ESOP Stock
          Fund, which is the portion of the Alliant Common Stock Fund comprised
          of the assets of the Alliant Common Stock Fund on January 1, 2002,
          plus any Company Contributions or Rollover Contributions thereafter
          which are invested to the Alliant Common Stock Fund, minus any
          transfers, withdrawals or distributions out of the Alliant Common
          Stock Fund attributable to the Alliant ESOP Fund pursuant to
          paragraphs 5.5 or 7.2 or Articles IX or X. In addition, on January 1,
          2003 and each January 1 thereafter, the Alliant ESOP Fund shall
          include the assets transferred to it from the Alliant Non-ESOP Fund.
          The Alliant ESOP Fund as in existence from time to time constitutes
          the employee stock ownership plan portion of the Plan and is intended
          to be primarily invested in the common stock of Alliant Energy
          Corporation.

2.5       Alliant Non-ESOP Fund means the Alliant Energy Corporation Non-ESOP
          Stock Fund, which is the portion of the Alliant Common Stock Fund
          attributable to Deferred Cash Contributions made after December 31,
          2001, plus any transfers to the Alliant Common Stock Fund after
          January 1, 2002 pursuant to paragraph 7.2 and any loan repayments to
          the Alliant Common Stock Fund after January 1, 2002 pursuant to
          paragraph 7.4, minus any transfers, withdrawals or distributions out
          of the Alliant Common Stock Fund attributable to the Alliant Non-ESOP
          Fund pursuant to paragraphs 5.4 or 7.2 or Articles IX or X.
          Notwithstanding the foregoing, on January 1, 2003 and each January 1
          thereafter, the assets in the Alliant Non-ESOP Fund shall be
          automatically transferred to the Alliant ESOP Fund, and the Alliant
          Non-ESOP Fund shall begin the year with no assets.

2.6       Beneficiary shall mean the Spouse, if then living, unless an
          alternative Beneficiary is designated by the Participant and such
          designation is consented to by the Spouse in accordance with
          procedures established by the Committee. In the event the Participant
          is not married or has no living Spouse, Beneficiary shall mean any
          person

                                       3

          designated as such by the Participant on a form supplied by the
          Committee to receive the benefits payable upon the death of the
          Participant. If no such designation is in effect at the time of the
          death of the Participant, or if no person so designated with the
          consent of the Spouse, if so required hereby, shall survive the
          Participant, the Beneficiary shall be the Spouse, if then living; and
          if the Spouse is not then living, then the Participant's estate. A
          Participant may at any time change a designated Beneficiary; provided,
          however, that no such change shall be effective unless in writing on
          forms provided by the Committee and provided any such designation is
          consented to by the Spouse. Except as otherwise provided in a valid
          beneficiary designation, a Beneficiary living at the death of a
          Participant may designate his own Beneficiary, and, in the event of
          death without a valid designation, the next Beneficiary shall be such
          Beneficiary's estate. Notwithstanding the foregoing, in the event of
          the Participant's divorce, the former spouse shall cease to be a
          Beneficiary unless after such divorce the Participant completes a new
          designation naming such individual as a Beneficiary.

2.7       Code means the Internal Revenue Code of 1986 as amended from time to
          time.

2.8       Committee means the Employee Total Compensation Committee appointed by
          the Board of Directors of the Corporation. Such Committee has the
          responsibility for the administration of the Plan as provided in
          Article XI.

2.9       Company means collectively, unless the context indicates otherwise,
          the Corporation, Alliant Energy Corporation, Interstate Power and
          Light Company, Wisconsin Power and Light Company, Alliant Energy
          Resources, Inc., Alliant Energy Integrated Services Company,
          Industrial Energy Applications, Inc., Schedin & Associates, Inc., SVBK
          Consulting Group, Inc., Cogenex Corporation, Energy Performance
          Services Inc., Alliant Energy International, Inc., Alliant Energy
          Investments, Inc., Heartland Properties, Inc., Capital Square
          Financial Corporation, Alliant Energy Transportation, Inc., Transfer
          Services, Inc., Williams Bulk Transfer Inc., Cedar Rapids and Iowa
          City Railway Co., and other Affiliated Companies to which the Plan has
          been extended by action of the Committee.

2.10      Company Contributions means the contributions made to the Plan by the
          Company on behalf of a Participant in accordance with paragraph 5.2.

2.11      Compensation means for a Participant for the Plan Year, the aggregate
          of:

          (a)  base pay and overtime pay, plus

          (b)  such incentive pay, if any, as is identified by the Committee,
               prior to the payment of any such amount, as includible as
               "Compensation" hereunder, plus

          (c)  the amount of any salary reduction contributions pursuant to Code
               Sections 125, 132(f), and 401(k) from the amounts in (a) and (b)
               above.

                                       4

          The maximum annual compensation taken into account hereunder for
          purposes of calculating any Participant's accrued benefit (including
          the right to any optional benefit) and for all other purposes under
          the Plan shall be two hundred thousand dollars ($200,000) or such
          higher amount permitted pursuant to Code Section 401(a)(17).

2.12      Corporation means Alliant Energy Corporate Services, Inc. or any
          successor or successors.

2.13      Deferred Cash Contributions means the contributions made to the Plan
          by the Company for a Participant in accordance with the Participant's
          contribution (payroll) deduction under Article IV.

2.14      Disability means the inability to engage in any substantial gainful
          activity by reason of any medically determinable physical or mental
          impairment, which impairment is, or is anticipated to be, total and
          permanent in the judgment of the Committee. Any Participant who
          receives long-term disability benefits pursuant to a plan sponsored by
          the Company is presumptively disabled for purposes of this Plan. The
          "Disability Date" is the date on which the Participant becomes
          disabled or the date the Participant begins to receive such disability
          benefits, whichever date the Participant so elects.

2.15      Employee Pretax Account means the Account reflecting a Participant's
          interest in the Plan related to Deferred Cash Contributions and
          previous employee pre-tax contributions as determined by the
          Committee.

2.16      Employer Contribution Account means the Account reflecting part or all
          of a Participant's interest in the Plan related to Company
          Contributions for applicable Participating Groups as provided in the
          applicable Schedules.

2.17      Employer Match A Account means the Account reflecting part or all of a
          Participant's interest in the Plan related to Company Contributions
          for applicable Participating Groups as provided in the applicable
          Schedules and/or prior employer contributions as determined by the
          Committee.

2.18      Employer Match B Account means the Account reflecting part or all of a
          Participant's interest in the Plan related to Company Contributions
          for applicable Participating Groups as provided in the applicable
          Schedules and/or prior employer contributions as determined by the
          Committee.

2.19      ERISA means the Employee Retirement Income Security Act of 1974, as
          amended from time to time.

2.20      Highly Compensated Employee means an employee defined in paragraph
          5.3.

2.21      Investment Funds means those funds defined in paragraph 7.1 hereof.

                                       5

2.22      Participant means an employee who satisfies the participation
          requirements of Article III.

2.23      Participant Loan Fund means the Investment Fund which reflects any
          amounts loaned to a Participant pursuant to paragraph 7.4 which are
          considered a segregated investment by such Participant.

2.24      Participating Group means a group of employees of the Company who are
          subject to substantially similar substantive provisions hereunder as
          provided in such group's applicable Schedule.

2.25      Plan means the "Alliant Energy Corporation 401(k) Savings Plan" as set
          forth in this document, and as amended from time to time.

2.26      Plan Year means a calendar year which begins on January 1 and ends on
          December 31.

2.27      Post-86 Aftertax Account means the Account reflecting a Participant's
          interest in the Plan related to after-tax employee contributions made
          after 1986 as determined by the Committee.

2.28      Pre-87 Aftertax Account means the Account reflecting a Participant's
          interest in the Plan related to after-tax employee contributions made
          prior to 1987 as determined by the Committee.

2.29      Prior Plan Monies Account means the Account reflecting a Participant's
          interest in the Plan related to certain prior employer contributions
          as determined by the Committee.

2.30      Rollover Contributions means a Participant's contributions as
          determined under paragraph 5.6 hereof.

2.31      Rollover Contribution Account means the Account reflecting a
          Participant's interest in the Plan related to Rollover Contributions
          and/or prior rollovers as determined by the Committee.

2.32      Schedule means one of the attachments at the end hereof that explain
          the substantive provisions applicable to the various Participating
          Groups.

2.33      Spouse means the person who is legally married to the Participant as
          of any date of reference.

2.34      Trust Agreement means any written agreement establishing a trust for
          purposes of receiving, holding, investing, and disposing of the Trust
          Fund.

2.35      Trust Fund means the Trust Fund established pursuant to a Trust
          Agreement for purposes of receiving and investing contributions made
          pursuant to this Plan and for

                                       6

          the purpose of paying distributions hereunder. Any such Trust shall be
          qualified under Code Section 501(a).

2.36      Trustee means the person acting as Trustee under any Trust Agreement.

2.37      Valuation Date means the date that Accounts are valued, i.e., each
          business day.


                                       7

                           ARTICLE III. PARTICIPATION
                           --------------------------

3.1       Eligibility Requirements.

          (a)  The eligibility requirements are identified for each
               Participating Group in the applicable Schedule.

          (b)  For purposes of this section, "hours of service" shall mean:

               (i)  each hour for which such employee is directly or indirectly
                    paid, or entitled to payment, for the performance of duties
                    for an Affiliated Company;

               (ii) each hour such employee is paid for holidays, vacation or
                    other time not worked;

               (iii) each hour such employee would have normally worked while on
                    disciplinary suspension or on approved leave-of-absence due
                    to sickness, accident, military service, or government
                    service during time of war, or other cause; provided
                    however, that he returns to active employment at the
                    expiration of such leave-of-absence, otherwise no hours of
                    service shall be credited for such periods;

               (iv) each hour such employee would have worked while disabled and
                    receiving payments under the terms of the Company's sick
                    leave plan or long-term disability plan; and

               (v)  each hour for which back pay, irrespective of mitigation of
                    damages, is either awarded or agreed to; provided, however,
                    that no more than five hundred one (501) hours shall be
                    credited for payments of back pay for a period of time
                    during which the employee performed no duties.

               When computing hours of service, overtime hours shall be treated
               as straight time hours; and there shall be no duplication of
               credit for hours which might otherwise be creditable under more
               than one of the above listed categories.

          (c)  A rehired employee in an eligible status who previously completed
               the eligibility requirements for the Participating Group in which
               rehired, shall be eligible to participate on the date of rehire.

3.2       Participation Requirements. To become a Participant in the Plan, an
          eligible employee must either:

          (a)  affirmatively make a contribution (payroll) deduction under
               paragraph 4.1 hereof, or

          (b)  elect to make a Rollover Contribution under paragraph 5.6 hereof.

                                       8


3.3       Duration of Participation. An employee who has become a Participant
          shall continue to be a Participant in the Plan until the first
          Valuation Date on which no balance remains in any of his Accounts.

3.4       Leased Employees. A person who is a "leased employee" within the
          meaning of Code Section 414(n) and (o) shall not be eligible to
          participate in the Plan, but in the event such a person was
          participating or subsequently becomes eligible to participate herein,
          credit shall be given for the person's service as a leased employee
          toward completion of the Plan's eligibility requirements, including
          any service for an Affiliated Company. A "leased employee" for this
          purpose is any person (other than a common law employee of an
          Affiliated Company) who, pursuant to an agreement between an
          Affiliated Company and any other person has performed services for the
          Affiliated Company on a substantially full-time basis for a period of
          at least one year, if such services are performed under the primary
          direction of or control by the Affiliated Company.

3.5       Collective Bargaining Unit Employees. An employee in a collective
          bargaining unit with which the Company has a bargaining agreement
          shall not be eligible to participate in the Plan unless, and then only
          to the extent, such bargaining agreement specifically provides.

3.6       Nonresident Alien. A person shall not be eligible to participate in
          the Plan if such person is a nonresident alien who receives no earned
          income from the Company that constitutes income from sources within
          the United States.

3.7       Common Law Employees. Coverage under the Plan is limited to persons
          who are treated by the Company as common law employees for federal
          employment tax purposes. In the event the Company changes its
          treatment of a person from independent contractor to common law
          employee, for whatever reason, coverage shall apply prospectively as
          of the date of such change.

                                       9

                    ARTICLE IV. DEFERRED CASH CONTRIBUTIONS
                    ---------------------------------------

4.1       Contribution (Payroll) Deduction. An eligible employee may elect to
          make Deferred Cash Contributions by a contribution (payroll) deduction
          in an amount in any multiple of one percent (1%) from zero percent
          (0%) of his Compensation up to a maximum of nineteen percent (19%).
          Such maximum percentage may be amended by action of the Committee from
          time to time, including the establishment of a separate maximum rate
          for Highly Compensated Employees. New or revised elections may be made
          on a daily basis in the manner provided by the Committee. The
          Committee may limit or reduce the Deferred Cash Contributions of
          Highly Compensated Employees, as provided for in paragraph 5.4 hereof.

          Notwithstanding the foregoing provisions of this paragraph 4.1 and
          subject to paragraph 10.1(e), the maximum amount that a Participant
          may elect to have contributed for any Plan Year pursuant to a
          contribution (payroll) deduction shall not exceed eleven thousand
          dollars ($11,000) in 2002 and the applicable amount for future years
          as provided in Code Section 402(g), reduced by the amount of any
          contributions made by an Affiliated Company for such Plan Year on
          behalf of the Participant pursuant to a salary reduction agreement
          under any other qualified plan under Code Section 401(k) maintained by
          the Affiliated Company. In the event such limitation is exceeded for a
          Plan Year, then, notwithstanding any other provision of the Plan or
          law, such excess, to the extent it has been contributed to the Plan,
          plus any income and minus any loss allocable thereto, shall be
          distributed to the Participant not later than April 15 next following
          the end of such Plan Year. Excess contributions to be distributed from
          an Employee Pretax Account, plus any income and minus any loss
          allocable thereto, shall be distributed from the Investment Funds in
          which such Account is invested at the time of distribution pro rata in
          accordance with the balance of the Account in each of the Investment
          Funds as of the Valuation Date next preceding the date of distribution
          but adjusted for any later loan made from the Account, except that no
          amount shall be distributed from the Account invested in the
          Participant Loan Fund until the balance in the other Investment Funds
          has been distributed. For purposes of this paragraph, the income or
          loss allocable to the excess contributions to be distributed from such
          Account for a Plan Year shall be determined by multiplying the total
          income or loss of the Account for such Plan Year by a fraction, the
          numerator of which is the excess contributions to be distributed from
          such account for such Plan Year and the denominator of which is the
          balance in such Account as of the end of such Plan Year.

4.2       Age 50 Catch-Up Contributions. Effective July 1, 2002, additional
          Deferred Cash Contributions shall be permitted on a pre-tax basis for
          Participants who are at least age forty-nine (49) by the December 31
          preceding the applicable calendar year in the amount of $1,000 for
          2002, $2,000 for 2003, $3,000 for 2004, $4,000 for 2005 and $5,000 for
          2006 and thereafter (as adjusted by cost of living increases pursuant
          to Code Section 414(v)). Such catch-up contributions shall be
          collected pursuant to the payroll deduction election of the
          Participant in the manner determined by the Committee. Eligible
          Participants are those who have attained the stated age and

                                       10

          otherwise reach the limitation on Deferred Cash Contributions imposed
          either by law or by the design of the Plan. For all purposes of the
          Plan such catch-up contributions shall be treated as Deferred Cash
          Contributions, except to the extent that such catch-up contributions
          shall not be eligible for matching contributions hereunder nor subject
          to any restrictions hereunder such as paragraphs 4.1 and 5.4 except as
          otherwise specified in Code Section 414(v).

4.3       Effect of Contribution (Payroll) Deduction. A Participant who has a
          contribution (payroll) deduction in effect for any Plan Year will have
          the elected portion of his Compensation deferred in order to have it
          contributed to the Plan by the Company on behalf of the Participant as
          a Deferred Cash Contribution. A contribution (payroll) deduction shall
          become effective as soon as practicable commencing after the later of
          the election or the applicable entry date. Once effective, a
          contribution (payroll) deduction shall remain in effect until the
          earliest of the following events to occur:

          (a)  The applicable date determined by the Committee following the
               Company's receipt of the Participant's notification changing his
               contribution (payroll) deduction;

          (b)  The Participant's termination date;

          (c)  The Disability Date of the Participant;

          (d)  The application of the adjustment defined in paragraph 5.4 or the
               limitation provided in paragraphs 4.1 and 4.2; or

          (e)  The receipt of a hardship withdrawal in accordance with paragraph
               10.1.

                                       11

                            ARTICLE V. CONTRIBUTIONS
                            ------------------------

5.1       Deferred Cash Contributions. The Company shall periodically make
          Deferred Cash Contributions to this Plan, equal to the amounts elected
          by Participants in accordance with Article IV hereof. The Company
          shall periodically forward all Deferred Cash Contributions to the
          Trustee as soon as practicable in the form of cash; provided all such
          contributions are so forwarded by the fifteenth (15th) day of the
          month following the salary deferral.

5.2       Company Contributions. Subject to the provisions of paragraph 5.4, the
          Company shall make Company Contributions for each of its Participants
          in the amounts identified for each Participating Group in the
          applicable Schedule. The Company shall periodically forward all
          Company Contributions to the Trustee; provided that all Company
          Contributions in respect of a pay period are so forwarded no later
          than the time for filing (including extensions thereof) the Company's
          Federal income tax return for the tax year in which such pay period
          occurs. Company contributions shall be allocated to the applicable
          Account as provided for the Participating Group in the applicable
          Schedule.

5.3       Actual Deferral Percentage. The actual deferral percentage for a
          specified group of employees eligible to be Participants pursuant to
          paragraph 3.1 (as hereinafter described) for a Plan Year shall be the
          average of one hundred (100) times the result (calculated separately
          for each employee in such group) obtained by dividing the amount of
          Deferred Cash Contributions actually paid to the Plan for each such
          employee for such Plan Year by the employee's compensation for the
          portion of such Plan Year for which Deferred Cash Contributions were
          made or could have been made for such employee. For the purposes of
          this paragraph and the second paragraph of paragraph 5.5, the term
          "compensation" means compensation for services performed for the
          Company that is currently includable in the employee's gross income
          and, if elected by the Company, any amounts contributed by the Company
          pursuant to a salary reduction agreement and which is not includable
          in the gross income of the employee under either Code Section 125 or
          402(a)(8). As soon as practicable after the end of the Plan Year, the
          Committee shall calculate the actual deferral percentages for the Plan
          Year for the group of employees who are Highly Compensated Employees
          for the Plan Year and for the group of employees who are not Highly
          Compensated Employees for the Plan Year. For the purposes of this
          Article V, the term "Highly Compensated Employee" means:

          (a)  A highly compensated active employee includes any employee who
               performs service for the Affiliated Companies and who:

               (i)  was a five percent (5%) owner during the prior Plan Year or
                    the current Plan Year, or

                                       12

               (ii) received compensation from the Affiliated Companies in
                    excess of eighty-five thousand dollars ($85,000) (as
                    adjusted pursuant to Code Section 415(d)) during the prior
                    Plan Year.

          (b)  For purposes of this definition and the tests in paragraphs 5.4
               and 5.5, the compensation and contribution history of the merged
               plans prior to the merger date shall be considered and
               aggregated.

          (c)  The determination of who is a Highly Compensated Employee will be
               made in accordance with Code Section 414(q).

5.4       Required Test and Adjustment. The following test shall be applied
          separately to (i) those Participants who are not in a collective
          bargaining unit and (ii) those Participants who are in a collective
          bargaining unit, with each separate unit also being tested separately.
          Notwithstanding the provisions of paragraphs 4.1 and 5.1, if the
          actual deferral percentage for the employees eligible to be
          Participants pursuant to paragraph 3.1 who are Highly Compensated
          Employees for any Plan Year exceeds, or in the judgment of the
          Committee is likely to exceed, the greater of (a) or (b) as follows:

          (a)  The actual deferral percentage for the prior Plan Year for the
               employees who are not Highly Compensated Employees for such prior
               Plan Year, multiplied by 1.25, or

          (b)  The actual deferral percentage for such prior Plan Year for the
               employees who are not Highly Compensated Employees for such prior
               Plan Year, multiplied by two (2); provided, however, that the
               actual deferral percentage for the employees who are Highly
               Compensated Employees for the Plan Year may not exceed the actual
               deferral percentage for the prior Plan Year for the employees who
               are not Highly Compensated Employees for such prior Plan Year by
               more than two (2) percentage points;

          then amounts contributed, or to be contributed, on behalf of
          Participants who are Highly Compensated Employees for such Plan Year
          shall be reduced at such time and in such manner as the Committee
          shall determine under rules and regulations uniformly applied and
          consistent with the following provisions of this paragraph so that the
          actual deferral percentage for employees who are Highly Compensated
          Employees for such Plan Year does not exceed the greater of (a) or (b)
          above. If during the Plan Year a Participant who is a Highly
          Compensated Employee for such Plan Year also participated in any other
          plan of the Company which includes a cash or deferred arrangement
          qualifying under Code Section 401(k), his compensation and
          contributions made pursuant to the cash or deferred arrangement under
          such other plan shall be taken into account for purposes of applying
          the tests under (a) or (b) above. In order to accomplish the
          foregoing, the Committee, in its discretion, may adjust the amount of
          contribution (payroll) deductions authorized pursuant to the
          provisions of paragraph 4.1 for such future period as may be required
          and shall do so by making such adjustments in the amounts to be
          contributed on behalf of

                                       13

          Participants who are Highly Compensated Employees for such Plan Year
          in the order of the contribution (payroll) deductions authorized by
          Participants who are Highly Compensated Employees beginning with the
          highest of such percentages. After the end of the Plan Year, if there
          are any excess amounts that must be refunded in order to satisfy the
          test, the Committee shall refund Deferred Cash Contributions
          previously made to the Highly Compensated Employees who made the
          contributions with the largest dollar amounts, leveling the maximum
          dollar amount until such excess is fully refunded. The amount by which
          Deferred Cash Contributions previously made on behalf of a Participant
          for a Plan Year is reduced, plus any income and minus any loss
          allocable thereto, shall be paid, notwithstanding any other provision
          of the Plan or law, to the Participant not later than the end of the
          following Plan Year. Such distribution shall be made from the
          Investment Funds in which the Participant's Employee Pretax Account is
          invested at the time of distribution pro rata in accordance with the
          balance of such Account in each of the Investment Funds as the
          Valuation Date next preceding the date of distribution but adjusted
          for any later loan made from the Account, except that no amount shall
          be distributed from the Account invested in the Participant Loan Fund
          until the balance in the other Investment Funds has been distributed.
          For purposes of this paragraph, the income or loss allocable to such
          contributions to be distributed from a particular Account for a Plan
          Year shall be determined by multiplying the total income or loss of
          the Account for such Plan Year by a fraction, the numerator of which
          is the amount of contributions to be distributed from such Account for
          such Plan Year and the denominator of which is the balance in such
          Account as of the end of the Plan Year.

5.5       Adjustment to Company Contribution Accounts. The following test shall
          be applied separately to (i) those Participants who are not in a
          collective bargaining unit and (ii) those Participants who are in a
          collective bargaining unit, with each separate unit also being tested
          separately. Notwithstanding the provisions of paragraph 5.2, if the
          average contribution percentage for the employees who are Highly
          Compensated Employees for any Plan Year exceeds, or in the judgment of
          the Committee is likely to exceed, the greater of (a) or (b) as
          follows:

          (a)  The average contribution percentage for the prior Plan Year for
               the eligible employees who are not Highly Compensated Employees
               for such prior Plan Year, multiplied by 1.25; or

          (b)  The average contribution percentage for such prior Plan Year for
               the employees who are not Highly Compensated Employees for such
               prior Plan Year, multiplied by two (2); provided, however, that
               the average contribution percentage for the employees who are
               Highly Compensated Employees for the Plan Year may not exceed the
               average contribution percentage for the prior Plan Year for the
               employees who are not Highly Compensated Employees for such prior
               Plan Year by more than two (2) percentage points; and provided
               further that the provisions of this subparagraph (b) shall be
               inapplicable to the extent prescribed by Treasury regulations to
               prevent the multiple use of this alternative limitation;

                                       14

          then the amounts contributed, or to be contributed, on behalf of
          Participants who are Highly Compensated Employees for such Plan Year
          shall be reduced at such time and in such manner as the Committee
          shall determine under rules and regulations uniformly applied and
          consistent with the following provision of this paragraph so that the
          average contribution percentage for the employees who are Highly
          Compensated Employees for such Plan Year does not exceed the greater
          of (a) or (b) above. If during the Plan Year a Participant who is a
          Highly Compensated Employee for such Plan Year also participated in
          any other plan of the Company to which employer matching contributions
          or employee contributions required to be taken into account hereunder
          are made, his compensation and such contributions made under such
          other plan shall be taken into account for purposes of applying the
          tests under (a) or (b) above. In order to accomplish the foregoing,
          the Committee, in its discretion, may adjust the amount of Company
          Contributions to be made pursuant to the provisions of paragraph 5.2
          for such future period as may be required and shall do so by making
          such adjustments in the amounts to be contributed to Accounts on
          behalf of Participants who are Highly Compensated Employees for such
          Plan Year in the order of the contribution percentage (determined in
          accordance with the last paragraph of this paragraph) of such
          Participants beginning with the highest of such percentages. After the
          end of the Plan Year, if there are any excess amounts that must be
          reduced in order to satisfy the test, the Committee shall reduce
          Company Contributions previously made to the Highly Compensated
          Employees with the largest dollar amounts, leveling the maximum dollar
          amount until such excess is fully reduced. The amount by which
          contributions previously made to a Participant's Account for a Plan
          Year are so reduced, plus any income and minus any loss allocable
          thereto, shall be paid to the Participant not later than the end of
          the following Plan Year. In addition, if reductions in a Participant's
          Deferred Cash Contributions are made pursuant to paragraph 5.4, the
          Committee shall reduce Company Contributions previously made with
          respect to any such contributions pursuant to the provisions of
          paragraph 5.2 and such amount, plus any income and minus any loss
          allocable thereto, shall be paid to the Participant not later than the
          end of the following Plan Year. Such reductions in contributions from
          the Participant's Account, plus any income and minus any loss
          allocable thereto, shall be made from the investment fund in which
          such contributions were invested. For purposes of this paragraph, the
          income or loss allocable to contributions for a Plan Year shall be
          determined by multiplying the total income or loss of the applicable
          Account for such Plan Year by a fraction, the numerator of which is
          the amount by which contributions to such Account are to be reduced
          for such Plan Year and the denominator of which is the balance in such
          Account as of the end of such Plan Year.

          For purposes of this paragraph, "average contribution percentage" for
          a specified group of employees eligible to be Participants pursuant to
          paragraph 3.1 for a Plan Year shall be the average of one hundred
          (100) times the result (calculated separately for each employee in
          such group) obtained by dividing the amount actually contributed to
          the Account of each such employee under paragraph 5.2 for such Plan
          Year by the employee's compensation for the portion of such Plan Year
          for which Company Contributions were made or could have been made for
          such employee.

                                       15

5.6       Rollover Contributions. An employee of the Company who is not excluded
          from participation pursuant to paragraph 3.5 or 3.6 may elect to
          rollover into the Plan (a "Rollover Contribution") in the form of cash
          any benefits of such employee arising out of participation by such
          employee or such employee's deceased spouse in an employee pension
          benefit plan maintained by an Affiliated Company or a former employer
          of such person or any individual retirement account to the maximum
          extent permitted by law, excluding after-tax accounts.

          An employee who makes a rollover into the Plan prior to becoming a
          Participant pursuant to paragraph 3.1 shall be treated as a
          Participant hereunder solely with respect to the rollover, until such
          time that the requirements of paragraph 3.1 are satisfied.


                                       16

                              ARTICLE VI. ACCOUNTS
                              --------------------

6.1       Valuation of Accounts. As of the end of each business day the
          Account(s) of each Participant shall be valued, subject to the
          adjustments described in paragraphs 6.2, 6.3, and 6.4 hereof. As soon
          as practicable after the end of each Plan Year, the Trustee shall
          cause to be delivered to the Participant, a statement summarizing the
          activity in the Participant's Account during the previous year and
          showing the value of investment in the Account, broken down by
          Investment Fund(s).

6.2       Allocation of Contributions and Withdrawals. After the end of each pay
          period, Deferred Cash Contributions and Company Contributions made by
          the Company on behalf of each Participant pursuant to Article V,
          during the pay period then ending, shall be added to the proper
          Account of each such Participant. All distributions pursuant to
          paragraphs 4.1, 5.4, and 5.5 and withdrawals made by Participants
          shall be deducted from the proper Account of each such Participant as
          of the date of payment.

6.3       Allocation of Net Earnings or Losses. As of each Valuation Date, there
          shall be determined the net earnings or losses of each of the
          Investment Funds, other than the Participant Loan Fund, adjusted for
          any costs or expenses payable from the Trust Fund pursuant to the
          Trust Agreement. Such net earnings or losses determined as of the
          Valuation Date, shall be allocated as of that date to the Account(s)
          of all Participants in the proportion that each Account balance is
          invested in such Investment Fund as of the preceding Valuation Date,
          adjusted for any withdrawals and distributions described in paragraph
          6.2, Participant loans made from such Investment Fund described in
          paragraph 7.4, transfers to the Investment Fund from other Investment
          Funds, transfers from the Investment Fund to other Investment Funds,
          Rollover Contributions made to such Investment Fund, and Deferred Cash
          Contributions, Company Contributions and interest and loan repayments
          on Participant loans made since the last Valuation Date and invested
          in such Investment Fund, bears to the total of all such Account
          balances in each Investment Fund so adjusted.

6.4       Allocation of Distributions. As of each Valuation Date, after the
          allocations under paragraphs 6.2 and 6.3 have been made, any
          distributions to be made to a Participant under Article IX shall be
          deducted from the proper Accounts of the Participant. The value of any
          distributions shall be based on the Valuation Date preceding the
          distribution.

6.5       Limitations on Allocations. The Plan is subject to the limitations on
          benefits and contributions imposed by Code Section 415 which are
          incorporated herein by this reference. The limitation year shall be
          the Plan Year. Any amounts not allocable to a Participant by reason of
          the limitations incorporated herein shall be allocated and reallocated
          during the limitation year among all other eligible Participants to
          the extent permitted by the limitations in lieu of Company
          Contributions. Any amounts

                                       17

          which cannot be allocated or reallocated due to the limitations shall
          be credited to a suspense account subject to the following conditions:

          (a)  amounts in the suspense account shall be allocated in lieu of
               Company Contributions among all eligible Participants hereunder
               at such time, including termination of the Plan or complete
               discontinuance of Company contributions, as the foregoing
               limitations permit,

          (b)  no investment gains or losses shall be allocated to the suspense
               account,

          (c)  no further Company contributions shall be permitted until the
               foregoing limitations permit their allocation to Participant's
               accounts, and

          (d)  upon termination of the Plan any unallocated amounts in the
               suspense account shall revert to the Company.


                                       18

                     ARTICLE VII. INVESTMENT OF TRUST FUNDS
                     --------------------------------------

7.1       Investment Funds. Contributions made under this Plan shall be
          deposited in the Trust Fund for purposes of investment. The Trust Fund
          shall consist of the Alliant Common Stock Fund, the Participant Loan
          Fund and at least three (3) or more additional Investment Funds as
          shall be designated from time to time by the Committee. Investment
          Funds are not separate trust funds but are funds reflecting various
          types of investments that the Trustee shall from time to time
          establish upon direction of the Committee. Each Participant's share in
          the Trust Fund shall consist of an undivided interest in the
          respective assets allocated to one (1) or more of such Investment
          Funds from time to time. Except as otherwise provided, each
          Participant's share in each such Investment Fund as of any Valuation
          Date shall be that proportion of such Investment Fund that his
          Accounts in such Investment Fund as of such date bear to the total
          Accounts of all Participants in such Investment Fund as of the
          Valuation Date that such share is being determined.

7.2       Investment Elections.

          (a)  A Participant's Account(s) and new contributions thereto shall be
               invested in one (1) or more of the Investment Funds. Except as
               otherwise provided herein, the allocation among the Investment
               Funds shall be directed by the Participant in the manner and to
               the extent provided by the Committee.

          (b)  Amounts invested in the Alliant Common Stock Fund shall be
               automatically divided between the Alliant ESOP Fund and the
               Alliant Non-ESOP Fund by the nature of such funds, without
               direction by the Participant.

          (c)  Amounts in the Employer Match A Account shall be automatically
               invested in the Alliant Common Stock Fund and shall remain in
               such fund until distribution or withdrawal pursuant to paragraph
               5.5 or Articles IX or X with two exceptions.

               (i)  During the thirty (30)-day period immediately prior to
                    "retirement," a Participant who is a bargaining unit
                    employee of Wisconsin Power and Light Company or Interstate
                    Power Company may redirect part or all of the assets of the
                    Employer Match A Account into any other Investment Fund. For
                    such purpose, "retirement" means the termination of
                    employment with the Affiliated Companies by reason of
                    retirement in accordance with the Wisconsin Power and Light
                    Company Retirement Plan B or the Interstate Power Company
                    Retirement Income Plan, as applicable, or their successors.

               (ii) For a period of six (6) Plan Years (unless the qualified
                    Participant's account has theretofore been completely
                    distributed), beginning with the later of 2003 or the year
                    next following the year in which a Participant becomes a
                    qualified Participant, a qualified Participant may

                                       19

                    elect to transfer the eligible diversification amount out of
                    the Alliant Common Stock Fund. A Participant becomes a
                    qualified Participant in the later of the Plan Year in which
                    he attains age fifty-five (55) or completes ten (10) years
                    of participation in the Plan, as determined by the
                    Committee; a Participant remains a qualified Participant
                    following termination of employment until his account has
                    been completely distributed. The eligible diversification
                    amount is the result obtained by subtracting transfers in
                    prior years from the Alliant Common Stock Fund related to
                    the Employer Match A Account under this diversification
                    provision, from twenty-five percent (25%) of the sum of (i)
                    the Participant's account balance in the Employer Match A
                    Account as of the December 31 immediately preceding an
                    election to transfer, and (ii) such prior transfers;
                    provided, however, that in the sixth (6th) year in which an
                    election hereunder may be made, fifty percent (50%) shall be
                    substituted for twenty-five percent (25%). An election to
                    transfer hereunder shall be made during the first ninety
                    (90) days of the Plan Year in the manner prescribed for such
                    purpose by the Committee; an election may be revoked or
                    modified during such ninety (90)-day period.

          (d)  The Plan is intended to constitute a plan described in ERISA
               Section 404(c) with respect to all investments except those funds
               in the Employer Match A Account.

7.3       Special Provisions Re: Common Stock of Alliant Energy Corporation.

          (a)  The Alliant Common Stock Fund shall be invested in the common
               stock of Alliant Energy Corporation, which stock constitutes
               "qualifying employer securities" as defined in ERISA, and such
               cash equivalent as is deemed appropriate by the Committee for
               liquidity purposes from time to time. Such qualifying employer
               securities shall be acquired, held and disposed of in accordance
               with the terms and provisions of this Plan; subject, however, to
               such limitations, if any, as may be provided for in ERISA. Any
               dividends received on common stock in this fund shall be
               reinvested by the Trustee in common stock of Alliant Energy
               Corporation as soon as possible.

          (b)  Each Participant shall have the right to direct the Trustee as to
               the exercise of all voting rights with respect to the
               Participant's proportional interest in common stock of Alliant
               Energy Corporation held in the Alliant Common Stock Fund. If the
               Trustee has not received directions as to the voting of any such
               stock by the fifth (5th) day before the meeting of shareholders
               at which such vote is to be taken, then such non-voted shares
               shall be voted by the Trustee pursuant to the directions of the
               Committee. There shall be delivered to such Participant all
               reports, financial statements, proxies and proxy soliciting
               material which are delivered to holders of common stock of
               Alliant Energy Corporation in connection with each meeting of
               stockholders.

                                       20

          (c)  Purchases and sales of common stock of Alliant Energy Corporation
               may be made by the Trustee on the open market or directly from or
               to Alliant Energy Corporation. For each Investment Date, for
               shares purchased directly from or sold directly to Alliant Energy
               Corporation, the price of all shares purchased or sold under the
               Plan will be the weighted average purchase price determined as
               follows: the average of the high and low prices, carried to three
               decimal places, of the common stock of Alliant Energy Corporation
               reported as New York Stock Exchange - Composite Transactions on
               the date of purchase or sale by the Trustee, "the Investment
               Date" (or, if no trading in the common stock of Alliant Energy
               Corporation occurs on such Exchange on the Investment Date on the
               next preceding day on which the common stock is so traded).

          (d)  Notwithstanding any other provisions of the Plan, a Participant
               may elect to receive a current cash payment of any dividends paid
               on shares of Alliant Energy Corporation common stock in the
               Alliant Common Stock Fund attributable to the Alliant ESOP Fund.
               Such election shall be made in the manner provided by the
               Committee. The Committee shall decide from time to time whether
               payments of dividends shall be made quarterly, semi-annually or
               annually, but in no event shall such payments be made later than
               ninety (90) days after the end of the Plan Year in which the
               dividends are paid by the Company. Any check processing fee
               charged by the Trustee or other service provider shall be charged
               against the Participant's Account(s) and shall be subtracted from
               such Investment Fund as is determined according to rules
               established by the Committee. In the event a Participant fails to
               make an election, the dividends shall be retained in the Alliant
               ESOP Fund. This election for a current distribution of dividends
               shall not apply to dividends attributable to the Alliant Non-ESOP
               Fund.

7.4       Loans.

          (a)  Upon the application of a Participant, the Committee, in
               accordance with a uniform and nondiscriminatory policy, may
               direct the Trustee to make a loan to such Participant for any
               reason. Loans shall be made upon such terms as the Committee
               shall specify consistent with the provisions of this paragraph.
               Any loan approved by the Committee will be disbursed on such date
               as the Committee shall direct provided the Participant is then an
               employee.

          (b)  The amount of any loan shall be charged against the Participant's
               Account(s) in the manner determined by the Committee and against
               the Investment Fund, other than the Participant Loan Fund, in
               which such Account(s) is invested pro rata in accordance with the
               balance of such Account(s) in each of such Investment Funds as of
               the Valuation Date prior to the date the loan is made. A loan
               application fee shall be charged against the Participant's
               Account(s) and shall be subtracted from such Investment Fund as
               is determined according to rules established by the Committee.

                                       21

          (c)  No loan to any Participant, when added to the outstanding balance
               of all other loans from the Plan made to the Participant, shall
               exceed the smallest of:

               (i)  fifty thousand dollars ($50,000), reduced by the excess, if
                    any, of the highest outstanding balance of all loans from
                    all qualified plans of the Affiliated Companies, to the
                    Participant during the one (1) year period ending on the day
                    before the date on which the loan is made over the
                    outstanding balance of loans from such plans to the
                    Participant on the date the loan is made;

               (ii) fifty percent (50%) of the balance in the Participant's
                    Account, as of the most recent Valuation Date for which a
                    valuation is available, as adjusted for any distributions,
                    withdrawals, contributions or loan payments made after such
                    Valuation Date;

               (iii) the balance of the eligible Participant's Accounts but
                    excluding the Employer Match A Account and the Employer
                    Contribution Account; or

               (iv) such other limit as the Committee may impose on a uniform
                    and consistent basis.

          (d)  The rate of interest on a loan made in any given Plan Year, and
               for the duration of such loan, shall be determined from time to
               time by the Committee.

          (e)  Any loan to a Participant shall be repaid by the Participant in
               such manner as the Committee shall determine, subject to the
               limitations of this subparagraph. The Committee shall require
               that the loan and interest thereon be repaid biweekly by payroll
               deduction over a period which shall not exceed:

               (i)  ten (10) years where the proceeds of the loan are to be
                    applied to acquire a dwelling unit which within a reasonable
                    time (determined at the time the loan is made) is to be used
                    as the principal residence of the Participant, or

               (ii) five (5) years for all other loans.

               Each installment shall be paid through payroll deductions by the
               Company from the compensation of the Participant. The Company
               shall deposit with the Trustee the sums so deducted or paid. Any
               loan under the Plan may be prepaid without penalty. Partial
               prepayments shall not be permitted. Amounts received by the Trust
               Fund as a repayment of a loan to a Participant or as payment of
               interest on a loan to a Participant shall be added to the
               Participant's Account(s) on a pro rata basis against which
               amounts were withdrawn and allocated to the Investment Funds in
               accordance with the Participant's election under paragraph 7.2
               with respect to the investment of contributions in effect at the
               time. Principal amounts received by the Trust

                                       22

               Fund as a repayment of a loan to a Participant shall be
               subtracted from the Participant Loan Fund.

          (f)  Each loan to a Participant shall be evidenced by a note, payable
               to the order of the Trustee, for the amount of the loan including
               interest thereon. Each loan shall be secured by a pledge of the
               borrower's Account, which pledge shall give the Trustee a
               security interest in all of the Participant's then existing, and
               thereafter acquired, rights in his Account. By accepting the
               loan, the Participant automatically assigns, as security for the
               loan, such rights in his Account.

          (g)  If a loan installment is not fully paid within thirty (30) days
               following the biweekly due date, the Committee shall give written
               notice to the Participant (or former Participant). If such loan
               installment payment is not made within sixty (60) days
               thereafter, the Committee may direct the trustee to apply an
               amount equal to or less than fifty percent (50%) of the vested
               balance in the Participant's Account, to the extent permitted by
               law and applicable Internal Revenue Service regulations, by the
               amount of unpaid loan balance including interest then due. This
               amount would be treated as having been received by the
               Participant as a distribution under the plan. The Participant's
               interest in his/her Account shall be reduced in the order
               determined by the Committee.

          (h)  Loans shall be available to all Participants who are active
               employees on an equivalent basis.

          (i)  The terms of all Participant loans are subject to the review and
               approval of the Committee and are subject to appeal by the
               Participant in accordance with paragraph 11.3.

          (j)  The Committee shall not approve a loan of less than one thousand
               dollars ($1,000) and no more than three (3) loans shall be
               outstanding for a Participant at any one time.

          (k)  Notwithstanding the foregoing provisions of Article VII, upon
               termination of employment, for any reason other than Disability,
               all outstanding loans of the terminated Participant shall be
               payable in full. If full payment is not received within the
               thirty (30)-day grace period specified by the Trustee, the unpaid
               portion of the loan will be treated as having been received by
               the Participant as a distribution under the Plan to the extent
               permitted by law and applicable Internal Revenue Service
               regulations.

                                       23

                    ARTICLE VIII. NONFORFEITURE OF BENEFITS
                    ---------------------------------------

          Notwithstanding anything to the contrary contained in this Plan, a
          Participant's right to receive distributions from his Account(s) shall
          at all times be nonforfeitable.


                                       24

                           ARTICLE IX. DISTRIBUTIONS
                           -------------------------

9.1       Distributions as a Result of Termination or Disability.

          (a)  Except with respect to a Participant in pay status, if the
               balance in the Accounts of a terminated Participant does not
               exceed five thousand dollars ($5,000), the Participant shall
               receive a distribution equal to such value in a lump sum. Such
               distribution shall be made as soon as practicable after the
               Participant's termination date or the effective date of this
               restatement, if later.

          (b)  If the balance in the Accounts of a Participant exceeds five
               thousand dollars ($5,000), the Participant may make an election
               to request distribution of his Accounts in a form and at the time
               permitted under this subparagraph. Such distribution shall
               commence as soon as practicable after such election is made. In
               no event, however, shall distribution of a Participant's Account
               commence later than the end of the month following the January 1
               after attainment of age seventy and one-half (70 1/2) by the
               Participant, except that a Participant who remains employed by an
               Affiliated Company may elect to defer commencement until
               termination of employment. If an election is not made, the
               Participant's Accounts shall remain invested in the Plan. The
               Participant shall retain the right to change the investment
               allocation among the various Investment Funds in accordance with
               paragraph 7.2. A notice shall be provided to the Participant
               explaining his right to consider the benefit election for at
               least thirty (30) days, although a Participant may elect to
               commence benefits sooner than thirty (30) days after receiving
               the notice.

               (i)  An eligible Participant may elect a lump sum distribution.

               (ii) An eligible Participant may elect annual installments. The
                    period of time shall be elected by the Participant and shall
                    not exceed the life expectancy of the Participant or the
                    joint life expectancies of the Participant and the
                    Beneficiary, fixed as of the date of commencement. At any
                    time the Participant may elect to accelerate the payment of
                    the remaining Account in a lump sum.

               (iii) Special distribution options are applicable to a
                    Participant who was a participant in the Interstate Power
                    Company 401(k) Plan on April 30, 1998 with respect to the
                    entire Account. Installment payments may be made annually,
                    quarterly, or monthly, as elected by the Participant. In the
                    case of an election of quarterly or monthly payments, the
                    Participant's Account will be assessed an administrative fee
                    per check determined by the Committee. With respect to the
                    installment period, the Participant may elect prior to the
                    commencement of benefits to recalculate annually the life
                    expectancies of the Participant and, if the spouse is so
                    designated, the Beneficiary. In addition, upon eligibility
                    to commence benefit payments, such a Participant may elect
                    partial

                                       25

                    distributions in any amount and at any time, subject to the
                    assessment of an administrative fee per check.

          (c)  Where a Participant has elected a deferred or installment form of
               payment, any funds from time to time remaining in his Account
               shall be valued and adjusted as provided for in Article VI
               hereof.

          (d)  A distribution shall be made in cash, except that a Participant
               shall be entitled to elect to receive any amount in his Account
               which is invested in the Alliant Common Stock Fund, in whole
               shares of common stock of Alliant Energy Corporation. In order to
               exercise such election, the Participant shall so notify the
               Committee at the same time the Participant gives the Committee
               the notice of the form of benefit selected. Payments of partial
               distributions shall reduce the applicable Accounts in each
               Investment Fund, other than the Participant Loan Fund,
               proportionately.

          (e)  The provisions of the Plan are intended to comply with IRC
               Section 401(a)(9) which prescribes certain rules regarding
               minimum distributions and requires that death benefits be
               incidental to retirement benefits. All distributions under the
               Plan shall be made in conformance with IRC Section 401(a)(9) and
               the regulations thereunder which are incorporated herein by
               reference. The provisions of the Plan governing distributions are
               intended to apply in lieu of any default provisions prescribed in
               regulations; provided, however, that IRC Section 401(a)(9) and
               the regulations thereunder override any Plan provisions
               inconsistent with such Code Section and regulations. For purposes
               of this provision, the Plan will apply the minimum distribution
               requirements in accordance with the regulations that were
               proposed on January 17, 2001, notwithstanding any provision of
               the Plan to the contrary.

9.2       Direct Transfer of Eligible Rollover Distributions.

          (a)  Notwithstanding any provision of the Plan to the contrary that
               would otherwise limit a distributee's election under this
               paragraph, a distributee may elect, at the time and in the manner
               prescribed by the Committee, to have any portion of an eligible
               rollover distribution paid directly to an eligible retirement
               plan specified by the distributee in a direct rollover as such
               terms are defined herein.

          (b)  An eligible rollover distribution is any distribution of all or
               any portion of the balance to the credit of the distributee,
               except that an eligible rollover distribution does not include:
               any distribution that is one of a series of substantially equal
               periodic payments (not less frequently than annually) made for
               the life (or life expectancy) of the distributee or the joint
               lives (or joint life expectancies) of the distributee and the
               distributee's designated beneficiary, or for a specified period
               of ten (10) years or more; any distribution to the extent such
               distribution is required under Code Section 401(a)(9); any
               hardship withdrawal; any dividend payment pursuant to
               subparagraph 7.3(d) and the

                                       26

               portion of any distribution that is not includible in gross
               income (determined without regard to the exclusion for net
               unrealized appreciation with respect to employer securities).

          (c)  An eligible retirement plan is an individual retirement account
               described in Code Section 408(a), an individual retirement
               annuity described in Code Section 408(b), an annuity plan
               described in Code Section 403(a), or a qualified trust described
               in Code Section 401(a), an annuity contract under Code Section
               403(b), or an eligible plan under Code Section 457(b) maintained
               by a state, political subdivision of a state, or any agency of a
               state or political subdivision of a state that accepts the
               distributee's eligible rollover distribution.

          (d)  A distributee includes an employee or former employee. In
               addition, the employee's or former employee's surviving spouse
               and the employee's or former employee's spouse or former spouse
               who is the alternate payee under a qualified domestic relations
               order, as defined in Code Section 414(p), are distributees with
               regard to the interest of the spouse or former spouse.

          (e)  A direct rollover is a payment by the Plan to the eligible
               retirement plan specified by the distributee.

          (f)  Effective upon the issuance of final regulations applicable
               thereto, in the event that a distributee receiving a mandatory
               distribution in excess of one thousand dollars ($1,000) does not
               make an election between a direct rollover and a cash payment,
               the distribution shall be made in the form of a direct rollover
               to an individual retirement account selected for such purpose by
               the Committee.

9.3       Payments to Beneficiary. In the event of death of a Participant prior
          to distribution in full of his Accounts, any amounts remaining in his
          Accounts shall be paid to such Participant's Beneficiary. Except to
          the extent provided in subparagraph (b), such distribution shall be
          made in a lump sum within ninety (90) days following the date of death
          of the Participant, unless the Beneficiary is the Participant's estate
          and a fiduciary of the estate has not been appointed by such date, in
          which case payment shall be made as soon as administratively
          practicable. Any payment to a Beneficiary shall be made in cash,
          except that a Beneficiary shall be entitled to elect to receive any
          amount in his Account which is invested in the Alliant Common Stock
          Fund, in whole shares of common stock of Alliant Energy Corporation.
          In order to exercise such election, the Beneficiary shall so notify
          the Committee at least fifteen (15) days prior to the time the
          distribution is to be made. The Beneficiary shall have no right to
          change the Investment Funds selected by the Participant.

9.4       Provision Regarding Unpaid Loans. Notwithstanding the foregoing
          provisions of Article IX, if a distribution under this Article IX of a
          Participant's Account is to be made prior to repayment of any
          outstanding loan of the Participant, then the unpaid portion of all
          loans made to the Participant under the Plan will be treated as having
          been received by the Participant as a distribution under the Plan.

                                       27

9.5       Participant's Interest Not Transferable. Except as may be required by
          application of the tax withholding provisions of the Code or of a
          State's income tax laws or except as provided in paragraph 7.4(f), the
          interests of Participants and their Beneficiaries under this Plan and
          Trust Agreement are not subject to the claims of creditors and may not
          be voluntarily or involuntarily sold, transferred, alienated or
          assigned. Notwithstanding the preceding sentence, the Plan shall pay
          benefits to the person or persons named in a qualified domestic
          relations order, in accordance with procedures established by the
          Committee, in the amount and to the extent provided in such order. If
          any such order so directs, distribution of benefits to the alternate
          payee may be made in a lump sum pursuant to the Plan's procedures but
          at a time not permitted for distributions to the Participant.

9.6       Facility of Payment. When a person entitled to distributions under the
          Plan is under legal disability, or, in the Committee's opinion, is in
          any way incapacitated so as to be unable to manage his financial
          affairs, the Committee may direct the Trustee to pay such
          distributions to such person's legal representative; or the Committee
          may direct the application of such distributions for the benefit of
          such persons. Any payment made in accordance with the preceding
          sentence shall be a full and complete discharge of any liability for
          such payment under the Plan.

                                       28

                    ARTICLE X. WITHDRAWALS DURING EMPLOYMENT
                    ----------------------------------------

10.1      Hardship Withdrawals.

          (a)  To alleviate a hardship, the Committee, upon application by a
               Participant who is an active employee, may authorize a
               distribution from such Participant's Rollover Account and
               Employee Pretax Account. For purposes of this paragraph 10.1, the
               term "hardship" shall mean:

               (i)  Unreimbursed medical expenses described in Code Section
                    213(d) incurred by the Participant, the Participant's Spouse
                    or any dependents of the Participant as defined in Code
                    Section 152) or necessary for these individuals to obtain
                    medical care;

               (ii) Costs directly related to the purchase (excluding mortgage
                    payments) of a principal residence for the Participant;

               (iii) Payment of tuition and related educational fees for the
                    next twelve (12) months of post-secondary education for the
                    Participant, his Spouse, children or dependents;

               (iv) Payments necessary to prevent the eviction of the
                    Participant from his principal residence or foreclosure on
                    the mortgage of the Participant's principal residence; and

               (v)  Any other circumstance that the Internal Revenue Service
                    announces as qualifying as a "hardship" under Code Section
                    401(k).

          (b)  Before a hardship withdrawal is granted in accordance with this
               paragraph 10.1, the Participant shall be required to take any
               other withdrawals under this Article X, the maximum loan
               available to him under paragraph 7.4, and cash dividend payments
               under subparagraph 7.3(d). If such accounts are insufficient to
               meet the hardship, the Participant shall then be permitted to
               make a hardship withdrawal of an amount sufficient to alleviate
               the hardship.

          (c)  In no event shall the hardship withdrawal from the Employee
               Pretax Account exceed all Deferred Cash Contributions and the
               earnings on such contributions accumulated prior to October 1,
               1988.

          (d)  A request for a hardship withdrawal under this paragraph 10.1
               shall be made in the manner prescribed by the Committee. The
               Committee shall establish a uniform and nondiscriminatory policy
               for reviewing withdrawal applications and any determination made
               by the Committee shall be final (but subject to appeal under
               paragraph 11.3).

          (e)  The provisions of this subparagraph (e) shall apply to a
               Participant who receives a hardship withdrawal. Notwithstanding
               Article IV, such a

                                       29

               Participant shall not be permitted to have Deferred Cash
               Contributions made on his behalf to this Plan or any other plan
               qualified under Code Section 401(k) maintained by the Company or
               an affiliated company for six (6) months following his receipt of
               such hardship withdrawal. Notwithstanding Article IV, the amount
               of Deferred Cash Contributions for the Calendar Year following
               such withdrawal shall not exceed the Code Section 402(g) limit
               reduced by the amount of such Participant's Deferred Cash
               Contributions for the calendar year in which the withdrawal
               occurs.

          (f)  No more than one (1) such hardship withdrawal may be made by a
               Participant in any Plan Year.

          (g)  All hardship withdrawals shall be paid in a single lump sum as
               soon as practicable after application for a withdrawal is
               received and acted upon by the Committee. The withdrawal shall be
               made in cash, except that a Participant shall be entitled to
               elect to receive any amount that is attributable to an investment
               in the Alliant Common Stock Fund, in whole shares of common stock
               of Alliant Energy Corporation. In order to exercise such
               election, the Participant shall so notify the Committee at the
               same time the Participant gives the Committee the request for the
               withdrawal. Payments of withdrawals shall reduce the applicable
               Accounts in each Investment Fund, other than the Participant Loan
               Fund, proportionately.

10.2      Other In-Service Withdrawals.

          (a)  Once each Plan Year an active employee may elect to withdraw all
               or any portion of the employee's Rollover Account.

          (b)  After attainment of age fifty-nine and one-half (59 1/2), a
               Participant on May 29, 1998 who was a participant in the Iowa
               Southern Utilities Company Savings Incentive Plan on January 1,
               1994 shall be entitled to commence distribution of the entire
               Account in the forms available pursuant to paragraph 9.1(b)
               notwithstanding that such Participant is an active employee.

          (c)  After attainment of age fifty-nine and one-half (59 1/2), a
               Participant on May 29, 1998 who was a participant in the
               Interstate Power Company 401(k) Plan on April 30, 1998 shall be
               entitled to commence distribution of the entire Account in the
               forms available pursuant to paragraph 9.1(b) notwithstanding that
               such Participant is an active employee.

          (d)  A Participant on May 29, 1998 who was a participant in the Iowa
               Southern Utilities Company Savings Plan on January 1, 1994 shall
               be entitled once each Plan Year to withdraw all or any portion of
               such person's Post-86 Aftertax Account and Pre-87 Aftertax
               Account notwithstanding that such Participant is an active
               employee.

                                       30

          (e)  A Participant on May 29, 1998 who was a participant in the
               Interstate Power Company 401(k) Plan on April 30, 1998 shall be
               entitled once each Plan Year to withdraw all or any portion of
               such person's Rollover Account, Pre-87 Aftertax Account and Prior
               Plan Monies Account notwithstanding that such Participant is an
               active employee.

          (f)  The withdrawal shall be made in cash, except that a Participant
               shall be entitled to elect to receive any amount that is
               attributable to an investment in the Alliant Common Stock Fund,
               in whole shares of common stock of Alliant Energy Corporation. In
               order to exercise such election, the Participant shall so notify
               the Committee at the same time the Participant gives the
               Committee the request for the withdrawal. Payments of withdrawals
               shall reduce the applicable Accounts in each Investment Fund,
               other than the Participant Loan Fund, proportionately.

                                       31

                           ARTICLE XI. ADMINISTRATION
                           --------------------------

11.1      Plan Administered by Committee. The Plan shall be administered by the
          Employee Total Compensation Committee consisting of such number of
          persons (not less than three (3) or more than five (5)) who shall be
          appointed by and serve at the pleasure of the Board of Directors. No
          member of the Committee who is an Employee shall receive compensation
          for his services as a member of the Committee. The Committee shall
          have the duties specified hereunder, including, but not by way of
          limitation, the following:

          (a)  To select investment managers;

          (b)  To construe and interpret the Plan, decide all questions of
               eligibility and determine the amount, manner and time of payment
               of any benefits and loans under the Plan;

          (c)  To prescribe procedures to be followed for the proper and
               efficient administration of the Plan;

          (d)  To prepare and distribute information explaining the Plan to
               Participants;

          (e)  To receive from the Company and from Participants such
               information as shall be necessary for the proper administration
               of the Plan;

          (f)  To furnish the Company, upon request, such annual reports with
               respect to the administration of the Plan as are reasonable and
               appropriate;

          (g)  To receive from the Trustee or other institutions or individuals,
               and to review and keep on file, reports of the financial
               condition and of the receipts and disbursements for the Plan;

          (h)  To employ individuals to assist in the administration of the
               Plan;

          (i)  To keep such accounts and records as necessary or proper in the
               performance of its duties under the Plan;

          (j)  To establish and implement procedures necessary for determining
               whether an order is a qualified domestic relations order and to
               administer such procedures and any distributions under such order
               in a nondiscriminatory and consistent manner;

          (k)  To establish and implement procedures necessary to determine
               whether or not a request for withdrawal or loan meets the
               requirements specified herein; provided, however, that in no
               instance is the Committee required to audit the actual use of
               such funds once the Committee has determined that the request
               meets the conditions specified herein;

                                       32

          (l)  To direct the establishment of three (3) or more Investment
               Funds;

          (m)  To establish investment policies and objectives for each such
               Investment Fund; and

          (n)  To appoint an administrator as its agent.

          The Committee shall have no power to add to, subtract from or modify
          any of the terms of the Plan, or to change or add to any benefits
          provided by the Plan, or to waive or fail to apply any requirements of
          eligibility under the Plan except as hereinafter provided.
          Notwithstanding the foregoing, the Committee may enact nonsubstantive
          amendments to the Plan which are required exclusively for the purpose
          of either correcting administrative inefficiencies or of conforming
          the Plan with governmental laws, regulations, or requirements.

          Notwithstanding the foregoing, the Chairman of the Committee is
          authorized to adopt collectively bargained plan changes and
          substantially similar changes for non-collectively bargained
          employees.

          The Committee may act at a meeting, or by writing without a meeting,
          by the vote or written assent of a majority of its members. The
          Committee and any other person(s) to whom the Committee may delegate
          any duty or power in connection with the administration of the Plan,
          shall be entitled to rely conclusively upon, and shall be fully
          protected in any action taken in good faith in reliance upon any
          information, opinions or reports which shall be furnished to them by
          any accountant, counsel or other specialist, to the extent provided by
          law.

          The Committee shall have discretionary authority to determine
          eligibility for benefits and to construe the terms of the Plan; any
          such determination or construction shall be final and binding on all
          parties unless arbitrary and capricious.

11.2      Indemnity for Liability. The Company shall indemnify the members of
          the Committee, and each fiduciary who is an employee of the Company,
          against any and all claims, losses, damages, expenses, including
          counsel fees, incurred by said fiduciaries, and any liability
          including any amounts paid in settlement with such fiduciary's
          approval, arising from the fiduciary's action or failure to act;
          except when the same is judicially determined to be attributable to
          the gross negligence or willful misconduct of such fiduciary.

11.3      Appeal from Denial of Claims. If any claim for benefits under the Plan
          is wholly or partially denied by the Committee, the claimant shall be
          given notice in writing of such denial, by registered or certified
          mail. Such notice shall be given as soon as reasonable after the
          denial; and the notice of denial shall set forth the specific reasons
          for such denial, specific reference to pertinent Plan provisions on
          which the denial is based, and a description of the Plan's claim
          review procedure. The claimant shall be advised that such claimant or
          a duly authorized representative of the claimant may request a review
          by the entire Committee, of the decision denying the claim. Such

                                       33

          request for review must be in writing and filed with the Committee
          within forty-five (45) days after such notice of denial has been
          received by the claimant. Any such claimant may review pertinent
          documents and submit issues and comments in writing within the same
          forty-five (45) day period. If such a request is so filed, a review
          shall be made by the Committee within sixty (60) days after receipt of
          such request. The claimant may be present at such review, offer
          additional evidence, cross-examine witnesses and present arguments to
          the Committee to support the claim. The claimant shall be given
          written notice of the final decision resulting from such review, which
          shall include specific reasons for the decision and specific
          references to the pertinent Plan provisions on which the final
          decision is based.

11.4      USERRA Compliance. Notwithstanding any provision of the Plan to the
          contrary, contributions, benefits and service credit with respect to
          qualified military service will be provided in accordance with Code
          Section 414(u). Loan repayments will be suspended under the Plan as
          permitted under Code Section 414(u)(4).

                                       34

                     ARTICLE XII. AMENDMENT AND TERMINATION
                     --------------------------------------

12.1      Amendment. Except as otherwise provided herein and in Sections 2.9,
          4.1 and 11.1, Alliant Energy Corporation shall have the sole and
          exclusive right to amend or modify the Plan at any time and for any
          reason, by the action of its Board of Directors. Notwithstanding
          anything to the contrary, the Committee shall at all times administer
          the Plan in such fashion that the Plan is maintained as a benefit plan
          meeting the requirements of ERISA and Code Sections 401(a), 401(k),
          and 404(a), or any other applicable provisions of law and shall have
          the power to amend the Plan to comply with such requirements and to
          obtain a favorable determination letter from the Internal Revenue
          Service. No amendment of the Plan shall cause any part of the Trust
          Fund or a Participant's Account(s) to be used for, or diverted to,
          purposes other than the exclusive benefit of the Participants or their
          Beneficiaries. Notwithstanding the foregoing, no amendment to the Plan
          shall decrease a Participant's accrued benefit or vested percentage or
          eliminate an optional form of distribution for a previously accrued
          benefit to the extent required by law.

12.2      Right to Terminate Plan. The Corporation contemplates that the Plan
          shall be permanent. Nevertheless, in recognition of the fact that
          future conditions and circumstances cannot now be entirely foreseen,
          Alliant Energy Corporation reserves unto its Board of Directors the
          sole and exclusive right to terminate the Plan for any reason and at
          any time. Upon termination of the Plan, the Account(s) of each
          Participant shall be distributed to such Participant as a lump sum
          payment.

                                       35

                      ARTICLE XIII. TOP-HEAVY RESTRICTIONS
                      ------------------------------------

13.1      General. Notwithstanding any provision to the contrary herein, in
          accordance with Code Section 416, if the Plan is a top-heavy plan for
          any Plan Year, then the provisions of this Section shall be
          applicable. The Plan is "top-heavy" for a Plan Year if as of its
          "determination date" (i.e. the last day of the preceding Plan Year or
          the last day of the Plan's first Plan Year, whichever is applicable),
          the total present value of the accrued benefits of key employees (as
          defined in Code Section 416(i)(1) and applicable regulations) exceeds
          sixty percent (60%) of the total present value of the accrued benefits
          of all employees under the plan (excluding those of former key
          employees and employees who have not performed any services during the
          preceding one (1) year period) (as such amounts are computed pursuant
          to Section 416(g) and applicable regulations using a five percent (5%)
          interest assumption and a 1971 GAM mortality assumption) unless such
          plan can be aggregated with other plans maintained by the applicable
          controlled group in either a permissive or required aggregation group
          and such group as a whole is not top-heavy. Any nonproportional
          subsidies for early retirement and benefit options are counted
          assuming commencement at the age at which they are most valuable. In
          addition, a plan is top-heavy if it is part of a required aggregation
          group which is top-heavy. Any plan of a controlled group may be
          included in a permissive aggregation group as long as together they
          satisfy the Code Section 401(a)(4) and 410 discrimination
          requirements. Plans of a controlled group which must be included in a
          required aggregation group include any plan in which a key employee
          participates or participated at any time during the determination
          period (regardless of whether the plan has terminated) and any plan
          which enables such a plan to meet the Section 401(a)(4) or 410
          discrimination requirements. The present values of aggregated plans
          are determined separately as of each plan's determination date and the
          results aggregated for the determination dates which fall in the same
          calendar year. A "controlled group" for purposes of this Section
          includes any group employers aggregated pursuant to Code Sections
          414(b), (c) or (m). The calculation of the present value shall be done
          as of a valuation date which for a defined contribution plan is the
          determination date and for a defined benefit plan is the date as of
          which funding calculations are generally made within the twelve month
          period ending on the determination date. Solely for the purpose of
          determining if the Plan, or any other plan included in a required
          aggregation group of which this Plan is a part, is top-heavy (within
          the meaning of Section 416(g) of the Code) the accrued benefit of an
          Employee other than a key employee (within the meaning of Section
          416(i)(1) of the Code) shall be determined under:

          (a)  the method, if any, that uniformly applies for accrual purposes
               under all plans maintained by the controlled group, or

          (b)  if there is no such method, as if such benefit accrued not more
               rapidly than the slowest accrual rate permitted under the
               fractional accrual rate of Section 411(b)(1)(C) of the Code.

                                       36

13.2      Minimum Benefits. If a defined contribution plan is top-heavy in a
          Plan Year, non-key employee participants who have not separated from
          service at the end of such Plan Year will receive allocations of
          employer contributions and forfeitures at least equal to the lesser of
          three percent (3%) of compensation (as defined in Code Section 415)
          for such year or the percentage of compensation allocated on behalf of
          the key employee for whom such percentage was the highest for such
          year (including any salary reduction contributions). If a defined
          benefit plan is top-heavy in a Plan Year and no defined contribution
          plan is maintained, the employer-derived accrued benefit on a life
          only basis commencing at the normal retirement age of each non-key
          employee shall be at least equal to a percentage of the highest
          average compensation for five consecutive years, excluding any years
          after such Plan permanently ceases to be top-heavy, such percentage
          being the lesser of:

          (a)  twenty percent (20%), or

          (b)  two percent (2%) times the years of service after December 31,
               1983 in which a Plan Year ends in which the Plan is top-heavy.

          If the controlled group maintains both a defined contribution plan and
          a defined benefit plan which cover the same non-key employee, such
          employee will be entitled to the defined benefit plan minimum and not
          to the defined contribution plan minimum.

                                       37

                            ARTICLE XIV. LEVERAGING
                            -----------------------

14.1      Acquisition Loans. At the direction of the Board, the Trustee shall
          incur "Acquisition Loans" from time to time to finance the acquisition
          of Stock for the Trust Fund (such Stock being the "Financed Shares")
          or to repay a prior Acquisition Loan. An installment obligation
          incurred in connection with the purchase of Stock shall constitute an
          Acquisition Loan. An Acquisition Loan, shall be for a specific term,
          shall be a reasonable rate of interest and shall not be payable on
          demand except in the event of default. An Acquisition Loan may be
          secured by a collateral pledge of the Financed Shares so acquired. No
          other assets of the Trust Fund may be pledged as collateral for an
          Acquisition Loan and no lender shall have recourse against the Trust
          Fund other than any Financed Shares remaining subject to pledge. Any
          pledge of Financed Shares shall provide for the release of shares so
          pledged in a manner provided in paragraph 14.2. Repayments of
          principal and interest on any Acquisition Loan shall be made by the
          Trustee only from Company contributions paid in cash to enable the
          Trustee to repay such Acquisition Loan, from earnings attributable to
          such Company contributions, or from any cash dividends received by the
          Trust Fund on such Financed Shares. An Acquisition Loan may constitute
          an extension of credit to the Trust Fund from a party in interest (as
          defined in ERISA).

14.2      Loan Suspense Account. Financed Shares shall initially be credited to
          a "Loan Suspense Account" and shall be allocated to the Alliant Energy
          Corporation ESOP Stock Fund subaccounts of Participants as payments
          are made on the Acquisition Loan. The number of Financed Shares to be
          released from the Loan Suspense Account for allocation to eligible
          Participants' subaccounts in any year (as Company Contributions
          pursuant to paragraph 5.1) shall be equal to the number of shares in
          the Loan Suspense Account immediately before the release multiplied by
          whichever of the following fractions is applicable as determined by
          the Committee:

               (i)  If, but only if, the conditions in (A) through (D) below are
                    met, the numerator of the fraction shall be the amount of
                    principal paid on the Acquisition Loan for the year and the
                    denominator shall be the outstanding principal balance due
                    on the Acquisition Loan at the beginning of the year (or on
                    the date of the Acquisition Loan, if made after the
                    beginning of the Plan Year).

                    (A)  The Acquisition Loan provides for annual payments of
                         principal and interest at a cumulative rate that is not
                         less rapid at any time than level annual payments of
                         such amounts for ten (10) years.

                    (B)  Interest included in any loan payment is disregarded
                         only to the extent that it would be determined to be
                         interest under standard loan amortization schedules.

                                       38

                    (C)  The duration of the Acquisition Loan (considering any
                         new loan resulting from the renewal, extension or
                         refinancing of the initial loan as being part of the
                         same Acquisition Loan) does not exceed ten (10) years.

                    (D)  The Acquisition Loan provides for the release of any
                         Financed Shares held as collateral for the loan in the
                         manner specified in this paragraph.

               (ii) In any other case, the numerator of the fraction shall be
                    the amount of principal and interest paid for the year and
                    the denominator shall be the sum of the numerator plus the
                    total of principal and interest to be paid for all future
                    years.

          A separate Loan Suspense Account shall be established for each
          separate Acquisition Loan. Notwithstanding the foregoing, in the event
          payments for a Plan Year are based in part on dividends on Stock
          previously allocated to Participants' subaccounts, the portion of the
          Financed Shares released from the Loan Suspense Account attributable
          to dividends on Stock in Participants' subaccounts shall be deemed to
          be the number of shares with a fair market value equal to the amount
          of dividends so used, and such Stock shall be allocated to the
          applicable subaccounts based on the dividends generated by such
          subaccounts; any remaining Financed Shares released for that Plan Year
          shall be allocated as provided in paragraph 5.2.

14.3      Restrictions on Allocations. In accordance with the requirements of
          Code Section 409(n), to the extent that a Company shareholder sells
          Stock to the Trust Fund and elects (with the consent of the Company)
          nonrecognition of gain under Code Section 1042, no portion of the
          Stock purchased subject to Code Section 1042 (or any dividends or
          other income attributable thereto) may be allocated to the account of:

               (i)  the selling shareholder;

               (ii) his spouse, brothers or sisters (whether by the whole or
                    half blood), ancestors or lineal descendants; or

               (iii) any shareholder owning (as determined under Code Section
                    318(a)) more than twenty-five percent (25%) in value of any
                    class of Stock.

          In addition to the foregoing, no allocation of Company Contributions
          shall be made to such disqualified participants in lieu of such Stock.

14.4      Impact on Annual Additions Limitations. As provided in paragraph 6.5,
          the provisions of Code Section 415 shall be applicable, including the
          provisions which treat as the annual additions for any limitation year
          the principal repayment on the Acquisition Loan rather than the fair
          market value of the Financed Shares which are released for allocation
          from the Loan Suspense Account.

                                       39

14.5      Company Contributions. Notwithstanding Article V, the Company shall
          contribute each year such amount, if any, as may be necessary to
          permit the Trustee to pay currently maturing obligations under an
          Acquisition Loan, taking into account dividends and other income
          available to the Trustee for that purpose.

14.6      Excess Match. After the application of and notwithstanding paragraphs
          5.2 and 14.2, in the event that the market value of Financed Shares
          released from the Loan Suspense Account would result in an allocation
          in excess of the match contemplated in the applicable Schedules, the
          Committee shall increase the matching percentage of Participants who
          are not subject to the terms of collective bargaining agreements in
          the manner determined in the sole discretion of the Committee in order
          to allocate in full the shares released.

14.7      Nonterminable Rights. Except as otherwise permitted by applicable law,
          Financed Shares may not be subject to a put, call, or other option or
          buy-sell or similar arrangement while held by and when distributed
          from the Plan, whether or not the Plan is then an employee stock
          ownership plan.

                                       40

                                   Schedule A

                     Alliant Energy Corporate Services, Inc.
                        Wisconsin Power and Light Company
        Interstate Power and Light Company (all nonbargaining employees)
Interstate Power and Light Company (bargaining employees at the IES operations)

3.1(a)    An employee of the Company shall become eligible to participate in the
          Plan as of the first day of the calendar month immediately following
          the latest of:

          (i)  date of employment with the Company;

          (ii) attainment of age eighteen (18); and

          (iii) either:

               (1)  for a regular full-time or regular part-time employee
                    customarily scheduled to work at least fifty percent (50%)
                    of the time of a regular full-time employee, completion of
                    thirty (30) consecutive days of service; or

               (2)  for any other employee of the Participating Group,
                    completion of the first twelve (12) months of employment or
                    any subsequent calendar year during which at least one
                    thousand (1,000) hours of service are earned.

          For purposes of the WPL bargaining group, "regular" employee includes
          a "special temporary" employee.

5.2       The amount of the Company Contributions each pay period shall equal
          fifty percent (50%) of the Deferred Cash Contributions made on behalf
          of such Participant under paragraph 5.1 for the applicable pay period,
          provided, however, that in no event shall Company Contributions be
          made for any pay period in excess of fifty percent (50%) of six
          percent (6%) of the Participant's Compensation for such pay period. No
          later than ninety (90) days following the end of the Plan Year, an
          additional Company Contribution will be allocated to the accounts of
          all Participants who 1) were active Participants in the Plan as of the
          last day of the Plan Year, 2) had contributed six percent (6%) of
          Compensation during the Plan Year, and 3) did not receive a match
          equal to three percent (3%) of Compensation. The amount of the
          additional contribution shall be the difference between fifty percent
          (50%) of six percent (6%) of base pay in the Plan Year less the amount
          of Company Contributions previously applied to the Deferred Cash
          Contributions for the Plan Year. Company Contributions made on behalf
          of a Participant shall be allocated to the Employer Match A Account.

                                       41

                                  Schedule B

                         Alliant Energy Resources, Inc.
                   Alliant Energy Integrated Services Company
                      Industrial Energy Applications, Inc.
                           Schedin & Associates, Inc.
                           SVBK Consulting Group, Inc.
                               Cogenex Corporation
                        Energy Performance Services Inc.
                       Alliant Energy International, Inc.
                        Alliant Energy Investments, Inc.
                           Heartland Properties, Inc.
                      Capital Square Financial Corporation
                       Alliant Energy Transportation, Inc.
                             Transfer Services, Inc.
                           Williams Bulk Transfer Inc.

3.1(a)    An employee of the Company shall become eligible to participate in the
          Plan as of the first day of the calendar month immediately following
          the latest of:

          (i)  date of employment with the Company;

          (ii) attainment of age eighteen (18); and

          (iii) either:

               (1)  for a regular full-time or regular part-time employee
                    customarily scheduled to work at least fifty percent (50%)
                    of the time of a regular full-time employee, completion of
                    thirty (30) consecutive days of service; or

               (2)  for any other employee of the Participating Group,
                    completion of the first twelve (12) months of employment or
                    any subsequent calendar year during which at least one
                    thousand (1,000) hours of service are earned.

5.2       The amount of the "basic" Company Contributions each pay period shall
          equal four percent (4%) of base pay for the applicable pay period. The
          "basic" Company Contributions made on behalf of a Participant shall be
          allocated to the Employer Contribution Account.

          In addition, in the discretion of the Committee, there may be an
          "incentive match" Company Contributions equal to a percentage, up to a
          maximum fifty percent (50%), of the Deferred Cash Contributions made
          on behalf of such Participant under paragraph 5.1 for the applicable
          Plan Year, provided, however, that in no event shall incentive match
          Company Contributions be made for any Plan Year in

                                       42

          excess of fifty percent (50%) of six percent (6%) of the Participant's
          Compensation for such Plan Year. No later than ninety (90) days
          following the end of the Plan Year, an additional Company Contribution
          will be allocated to the accounts of all Participants who 1) were
          active Participants in the Plan as of the last day of the Plan Year,
          2) had contributed six percent (6%) of Compensation during the Plan
          Year, and 3) did not receive a match equal to three percent (3%) of
          Compensation. The amount of the additional contribution shall be the
          difference between fifty percent (50%) of six percent (6%) of base pay
          in the Plan Year less the amount of Company Contributions previously
          applied to the Deferred Cash Contributions for the Plan Year. Any
          "incentive" Company Contributions made on behalf of a Participant
          shall be allocated to the Employer Match B Account.

                                       43

                                  Schedule C

                     Cedar Rapids and Iowa City Railway Co.

3.1(a)    An employee of the Company shall become eligible to participate in the
          Plan as of the first day of the calendar month immediately following
          the latest of:

          (i)  date of employment with the Company;

          (ii) attainment of age eighteen (18); and

          (iii) either:

               (1)  for a regular full-time or regular part-time employee
                    customarily scheduled to work at least fifty percent (50%)
                    of the time of a regular full-time employee, completion of
                    thirty (30) consecutive days of service; or

               (2)  for any other employee of the Participating Group,
                    completion of the first twelve (12) months of employment or
                    any subsequent calendar year during which at least one
                    thousand (1,000) hours of service are earned.

5.2       The amount of "basic" Company Contribution each pay period shall equal
          two percent (2%) of base pay for the applicable pay period. The
          "basic" Company Contributions made on behalf of a Participant shall be
          allocated to the Employer Contribution Account.

          In addition, at the discretion of the Committee, there may be an
          "incentive match" Company Contributions equal to a percentage, up to a
          maximum fifty percent (50%), of the Deferred Cash Contributions made
          on behalf of such Participant under paragraph 5.1 for the applicable
          Plan Year, provided, however, that in no event shall incentive match
          Company Contributions be made for any Plan Year in excess of fifty
          percent (50%) of six percent (6%) of the Participant's Compensation
          for such Plan Year. No later than ninety (90) days following the end
          of the Plan Year, an additional Company Contribution will be allocated
          to the accounts of all Participants who 1) were active Participants in
          the Plan as of the last day of the Plan Year, 2) had contributed six
          percent (6%) of Compensation during the Plan Year, and 3) did not
          receive a match equal to three percent (3%) of Compensation. The
          amount of the additional contribution shall be the difference between
          fifty percent (50%) of six percent (6%) of base pay in the Plan Year
          less the amount of Company Contributions previously applied to the
          Deferred Cash Contributions for the Plan Year. Any "incentive" Company
          Contributions made on behalf of a Participant shall be allocated to
          the Employer Match B Account.

                                       44

                                  Schedule D

 Interstate Power and Light Company (bargaining employees at the IPC operations)

3.1(a)    Prior to July 1, 2002, an employee of the Company shall become
          eligible to participate in the Plan as of the first day of the
          calendar month immediately following the latest of:

          (i)  date of employment with the Company;

          (ii) attainment of age eighteen (18); and

          (iii) completion of the first twelve (12) months of employment or any
               subsequent calendar year during which at least one thousand
               (1,000) hours of service are earned.

          On and after July 1, 2002, an employee of the Company shall become
          eligible to participate in the Plan as of the first day of the
          calendar month immediately following the latest of:

          (iv) date of employment with the Company;

          (v)  attainment of age eighteen (18); and

          (vi) either:

               (1)  for a regular full-time or regular part-time employee
                    customarily scheduled to work at least fifty percent (50%)
                    of the time of a regular full-time employee, completion of
                    thirty (30) consecutive days of service; or

               (2)  for any other employee of the Participating Group,
                    completion of the first twelve (12) months of employment or
                    any subsequent calendar year during which at least one
                    thousand (1,000) hours of service are earned.

5.2       The amount of the Company Contributions each pay roll period shall
          equal fifty percent (50%) of the Deferred Cash Contributions made on
          behalf of such Participant under paragraph 5.1 for the applicable pay
          period, provided, however, that in no event shall Company
          Contributions be made for any pay period in excess of fifty percent
          (50%) of six percent (6%) of the Participant's Compensation for such
          pay period. No later than ninety (90) days following the end of the
          Plan Year, an additional Company Contribution will be allocated to the
          accounts of all Participants who 1) were active Participants in the
          Plan as of the last day of the Plan Year, 2) had contributed six
          percent (6%) of Compensation during the Plan Year, and 3) did not
          receive a match equal to three percent (3%)

                                       45

          of Compensation. The amount of the additional contribution shall be
          the difference between fifty percent (50%) of six percent (6%) of base
          pay in the Plan Year less the amount of Company Contributions
          previously applied to the Deferred Cash Contributions for the Plan
          Year.

          Company Contributions made on behalf of a Participant shall be
          allocated to the Employer Match A Account.

                                       46


          Pursuant to the authority granted to the undersigned by the
          Compensation and Personnel Committee of the Board of Directors of
          Alliant Energy Corporation, the foregoing be and it hereby is adopted
          as a restatement of the Alliant Energy Corporation 401(k) Savings Plan
          effective January 1, 2002.

                                       Dated this 30th day of January, 2002.


                                       -------------------------------------
                                       Erroll B. Davis, Jr.
                                       Chief Executive Officer
                                       Alliant Energy Corporation


                                       47