UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             Washington, D.C. 20549

                                  SCHEDULE 13G

                    Under the Securities Exchange Act of 1934

                                (Amendment No. _____ )*


                            INTERPUBLIC GROUP COS INC
--------------------------------------------------------------------------------
                                (Name of Issuer)


                     Common Stock, $.01 par value per share
--------------------------------------------------------------------------------
                         (Title of Class of Securities)


                                  US4606901001
--------------------------------------------------------------------------------
                                 (CUSIP Number)



                                December 31, 2004
--------------------------------------------------------------------------------
             (Date of Event Which Requires Filing of this Statement)


Check the appropriate box to designate the rule pursuant to which this Schedule
is filed:

         [ X ]   Rule 13d-1(b)

         [   ]   Rule 13d-1(c)

         [   ]   Rule 13d-1(d)


*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter the
disclosures provided in a prior cover page.

The information required in the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).








                                  SCHEDULE 13G

CUSIP No.         US4606901001


----------------------------------------------------------------------------------------------------------------------------
      

          1.   Names of Reporting Persons.  I.R.S.  Identification Nos. of above
               persons (entities only).
               AMVESCAP PLC

----------------------------------------------------------------------------------------------------------------------------

          2.   Check the Appropriate Box if a Member of a Group (see
               Instructions)
               (a)
               (b)

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          3.   SEC Use Only  _______________________________________________

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          4.   Citizenship or Place of Organization
               AMVESCAP PLC:  England
               AIM Advisors, Inc:  United States
               AIM Private Asset Management, Inc.:  United States
               INVESCO Asset Management Limited:  England
               AIM Capital Management, Inc.:  United States
               INVESCO Institutional (N.A.), Inc.:  United States
               INVESCO Asset Management GmbH:  Germany
               Stein Roe Investment Counsel, Inc.:  United States

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                                    5.      Sole Voting Power 23,115,284:  Such shares are held by the following
                                            entities in the respective amounts listed  AIM Advisors, Inc
                                            20,385,370, AIM Private Asset Management, Inc. 1,219,790,INVESCO Asset
                                            Management Limited 650,936, AIM Capital Management, Inc. 295,050, INVESCO
                                            Institutional (N.A.), Inc. 502,008,INVESCO Asset Management
                                            GmbH 15,474, Stein Roe Investment Counsel, Inc. 46,656

Number of Shares           --------------------------------------------------------------------------------------------------
Beneficially Owned
by Each Reporting                   6.      Shared Voting Power       _______________
Person With
                           --------------------------------------------------------------------------------------------------

                                    7.      Sole Dispositive Power     23,115,284:  Such shares are held by the following
                                            entities in the respective amounts listed  AIM Advisors, Inc
                                            20,385,370, AIM Private Asset Management, Inc. 1,219,790,INVESCO Asset
                                            Management Limited 650,936, AIM Capital Management, Inc. 295,050, INVESCO
                                            Institutional (N.A.), Inc. 502,008,INVESCO Asset Management
                                            GmbH 15,474, Stein Roe Investment Counsel, Inc. 46,656


                           --------------------------------------------------------------------------------------------------

                                    8.      Shared Dispositive Power     _______________
---------------------------------------------------------------------------------------------------------------------------- 9. Aggregate Amount Beneficially Owned by Each Reporting Person 23,115,284 ---------------------------------------------------------------------------------------------------------------------------- 10. Check if the Aggregate Amount in Row (9) Excludes Certain Shares (See Instructions) N/A ---------------------------------------------------------------------------------------------------------------------------- 11. Percent of Class Represented by Amount in Row (9) 5.47% ----- ---------------------------------------------------------------------------------------------------------------------------- 12. Type of Reporting Person (See Instructions) IA, HC. See Items 2 and 3 of this statement.
SCHEDULE 13G Item 1(a) Name of Issuer: INTERPUBLIC GROUP COS INC Item 1(b) Address of Issuer's Principal Executive Offices: 1114 Avenue of the Americas New York, NY 10020 Item 2(a) Name of Person Filing: AMVESCAP PLC In accordance with Securities and Exchange Commission Release No. 34-39538 (January 12, 1998), this statement on Schedule 13G or amendment thereto is being filed by AMVESCAP PLC ("AMVESCAP"), a U.K. entity, on behalf of itself and its subsidiaries listed in Item 4 of the cover of this statement. AMVESCAP through such subsidiaries provides investment management services to institutional and individual investors worldwide. Executive officers and directors of AMVESCAP or its subsidiaries may beneficially own shares of the securities of the issuer to which this statement relates (the "Shares"), and such Shares are not reported in this statement. AMVESCAP and its subsidiaries disclaim beneficial ownership of Shares beneficially owned by any of their executive officers and directors. Each of AMVESCAP's direct and indirect subsidiaries also disclaim beneficial ownership of Shares beneficially owned by AMVESCAP and any other subsidiary. Item 2(b) Address of Principal Business Office: 11 Devonshire Square London EC2M 4YR England Item 2(c) Citizenship: See the response to Item 2(a) of this statement. Item 2(d) Title of Class of Securities: Common Stock, $.01 par value per share Item 2(e) CUSIP Number: US4606901001 Item 3 Type of Reporting Person: An investment adviser in accordance with section 240.13d-1(b)(1)(ii)(E) A parent holding company or control person in accordance with section 240.13d-1(b)(1)(ii)(G) As noted in Item 2 above, AMVESCAP is making this filing on behalf of its subsidiaries listed herein. Each of these entities is either an investment adviser registered with the United States Securities Exchange Commission under Section 203 of the Investment Advisers Act of 1940, as amended, or under similar laws of other jurisdictions. AMVESCAP is a holding company.
Item 4 Ownership: Please see responses to Items 5-8 on the cover of this statement which are incorporated herein by reference. Item 5 Ownership of Five Percent or Less of a Class: --------------------------------------------- N/A Item 6 Ownership of More than Five Percent on Behalf of Another Person: ---------------------------------------------------------------- N/A Item 7 Identification and Classification of the Subsidiary Which Acquired the Security Being Reporting ------------------------------------------------------------------------------------------------ on By the Parent Holding Company: --------------------------------- Please see Item 3 of this statement, which is incorporated herein by reference. Item 8 Identification and Classification of Members of the Group: ---------------------------------------------------------- N/A Item 9 Notice of Dissolution of a Group: --------------------------------- N/A Item 10 Certification: By signing below I certify that, to the best of my knowledge and belief, the securities referred to above were acquired and are held in the ordinary course of business and were not acquired and are not held for the purpose of or with the effect of changing or influencing the control of the issuer of the securities and were not acquired and are not held in connection with or as a participant in any transaction having that purpose or effect. Signature: After reasonable inquiry and to the best of my knowledge and belief, I certify that the information set forth in this statement is true, complete and correct. February 14, 2005 -------------------------------------------- Date /s/ HAL LIEBES -------------------------------------------- Signature Hal Liebes Group Compliance Officer AMVESCAP PLC
EXHIBIT A

                             JOINT FILING AGREEMENT
                             ----------------------

         The undersigned agree that AMVESCAP PLC, the common parent company of
each of the undersigned, is authorized to sign and make joint filings on
Schedule 13G, including any and all amendments thereto, on behalf of each of the
undersigned pursuant to Rule 13d-1(k)(1) of the Securities and Exchange
Commission.

                                                           

                                                              /s/
                                                              -----------------------------------------
                                                              AIM Advisors, Inc.


                                                              /s/
                                                              -----------------------------------------
                                                              AIM Capital Management, Inc.


                                                              /s/
                                                              -----------------------------------------
                                                              AIM Funds Management, Inc.


                                                              /s/
                                                              -----------------------------------------
                                                              AIM Private Asset Management, Inc.


                                                              /s/
                                                              -----------------------------------------
                                                              AMVESCAP National Trust Company


                                                              /s/
                                                              -----------------------------------------
                                                              Atlantic Trust Advisors, Inc.


                                                              /s/
                                                              -----------------------------------------
                                                              Atlantic Trust Co., N.A.


/s/ ----------------------------------------- Atlantic Trust Company, N.A. /s/ ----------------------------------------- INVESCO Asia Limited /s/ ----------------------------------------- INVESCO Asset Management GmbH /s/ ----------------------------------------- INVESCO Asset Management Limited /s/ ----------------------------------------- INVESCO Asset Management, S.A. /s/ ----------------------------------------- INVESCO Asset Management Osterreich GmbH /s/ ----------------------------------------- INVESCO Global Asset Management (N.A.), Inc. /s/ ----------------------------------------- INVESCO GT Management Company S.A. /s/ ----------------------------------------- INVESCO GT Management S.A.
/s/ ----------------------------------------- INVESCO Institutional (N.A.), Inc. /s/ ----------------------------------------- INVESCO Italia SGR SpA /s/ ----------------------------------------- INVESCO Maximum Income Management S.A. /s/ ----------------------------------------- INVESCO Private Capital, Inc. /s/ ----------------------------------------- INVESCO Senior Secured Management, Inc. /s/ ----------------------------------------- INVESCO Taiwan Limited /s/ ----------------------------------------- INVESCO Asset Management (Japan) Limited /s/ ----------------------------------------- INVESCO Asset Management Ireland Limited /s/ ----------------------------------------- INVESCO Kapitalanlagegesellschaft GmbH /s/ ----------------------------------------- Stein Roe Investment Counsel, Inc.