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                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

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

                                   SCHEDULE TO
                                 (Rule 14d-100)
            TENDER OFFER STATEMENT UNDER SECTION 14(d)(1) OR 13(e)(1)
                     OF THE SECURITIES EXCHANGE ACT OF 1934

                             COMSHARE, INCORPORATED
                       (Name of Subject Company (Issuer))

                           CONDUCTOR ACQUISITION CORP.
                                    (Offeror)
                     an indirect wholly-owned subsidiary of
                        GEAC COMPUTER CORPORATION LIMITED
                               (Parent of Offeror)
                            (Names of Filing Persons)

                     COMMON STOCK, PAR VALUE $1.00 PER SHARE
                         (Title of Class of Securities)

                                    205912108
                      (CUSIP Number of Class of Securities)

                                CHARLES S. JONES
                                    CHAIRMAN
                        GEAC COMPUTER CORPORATION LIMITED
                         11 ALLSTATE PARKWAY, SUITE 300
                            MARKHAM, ONTARIO L3R 9T8
                                     CANADA
                                 (905) 475-0525
                 (Name, address, and telephone numbers of person
               authorized to receive notices and communications on
                            behalf of filing persons)

                                 with copies to:
                          ROBERT W. SWEET, JR., ESQUIRE
                                 FOLEY HOAG LLP
                              155 SEAPORT BOULEVARD
                           BOSTON, MASSACHUSETTS 02210
                                 (617) 832-1000




                            CALCULATION OF FILING FEE

<Table>
<Caption>
   Transaction valuation*                             Amount of filing fee**
   ----------------------                             ----------------------
                                                   
        $52,008,427                                          $4,208
</Table>

*Estimated for purposes of calculating the amount of the filing fee only. This
amount assumes the purchase at $4.60 per share in cash, pursuant to the Offer to
Purchase, of all 10,827,583 issued and outstanding shares of common stock, par
value $1.00 per share, of Comshare, Incorporated as of June 30, 2003 plus the
aggregate amount in cash to be paid to holders of outstanding options to
purchase shares of Comshare common stock determined by multiplying the excess,
if any, of $4.60 over the applicable exercise price of each such option by the
number of shares of Comshare common stock underlying such option.

**The amount of the filing fee, calculated in accordance with Rule 0-11 of the
Securities Exchange Act of 1934, as amended, equals $80.90 per $1,000,000 of the
transaction value.

[ ]    Check the box if any part of the fee is offset as provided by Rule
       0-11(a)(2) and identify the filing with which the offsetting fee was
       previously paid. Identify the previous filing by registration statement
       number, or the Form or Schedule and the date of its filing.

                        Amount Previously Paid:
                                               --------------------
                        Form or Registration No.:
                                                 ------------------
                        Filing Party:
                                     ------------------------------
                        Date Filed:
                                   --------------------------------

[ ]    Check the box if the filing relates solely to preliminary communications
       made before the commencement of a tender offer.

Check the appropriate boxes below to designate any transactions to which the
statement relates:

[X]    third-party tender offer subject to Rule 14d-1.

[ ]    issuer tender offer subject to Rule 13e-4.

[ ]    going-private transaction subject to Rule 13e-3.

[ ]    amendment to Schedule 13D under Rule 13d-2

Check the following box if the filing is a final amendment reporting the results
of the tender offer:

[ ]

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                                   SCHEDULE TO

         This Tender Offer Statement on Schedule TO ("Schedule TO") relates to
the offer by Conductor Acquisition Corp., a Michigan corporation ("Purchaser")
and an indirect wholly owned subsidiary of Geac Computer Corporation Limited, a
corporation governed by the Canada Business Corporations Act ("Geac"), to
purchase all of the outstanding shares of Common Stock, par value $1.00 per
share (the "Shares"), of Comshare, Incorporated, a Michigan




corporation (the "Company"), at a purchase price of $4.60 per Share, net to the
seller in cash, without interest thereon, upon the terms and subject to the
conditions set forth in the Offer to Purchase, dated July 1, 2003 (the "Offer
to Purchase"), and in the related Letter of Transmittal (the "Letter of
Transmittal" which, together with the Offer to Purchase, as each may be amended
and supplemented from time to time, constitute the "Offer").

ITEMS 1 THROUGH 9, AND ITEM 11.


         The information set forth in the Offer to Purchase and the Letter of
Transmittal, copies of which are filed with this Schedule TO as Exhibits
(a)(1)(A) and (a)(1)(B) hereto, respectively, are incorporated herein by
reference in answer to Items 1 through 9 and 11 of this Tender Offer Statement
on Schedule TO.

ITEM 10. FINANCIAL STATEMENTS.

         Not Applicable.

ITEM 12. EXHIBITS.

         (a)(1)(A)  Offer to Purchase, dated July 1, 2003.

         (a)(1)(B)  Letter of Transmittal.

         (a)(1)(C)  Notice of Guaranteed Delivery.

         (a)(1)(D)  Letter to Brokers, Dealers, Banks, Trust Companies and other
                    Nominees.

         (a)(1)(E)  Letter to Clients for use by Brokers, Dealers, Banks, Trust
                    Companies and other Nominees.

         (a)(1)(F)  Press Release dated July 1, 2003.


         (a)(1)(G)  Summary Advertisement, published in the New York Times
                    on July 1, 2003.


         (b)        Not Applicable.

         (c)        Not Applicable.

         (d)(1)     Confidentiality Agreement dated April 24, 2003 between Geac
                    and the Company.

         (d)(2)     Confidentiality Agreement effective May 1, 2003 between
                    Geac and the Company.

         (d)(3)     Agreement and Plan of Merger, dated as of June 22, 2003, by
                    and among Geac, Purchaser and the Company.


                                      -3-


         (d)(4)     Voting and Tender Agreement, dated as of June 22, 2003, by
                    and among Geac, Purchaser and Dennis G. Ganster.

         (d)(5)     Voting and Tender Agreement, dated as of June 22, 2003, by
                    and among Geac, Purchaser and each of Codec Systems Limited
                    and Anthony Stafford.

         (d)(6)     Employment agreement dated June 19, 2003 by and among the
                    Company, Geac Computers, Inc., Geac and Brian Hartlen.

         (d)(7)     Employment agreement dated June 19, 2003 by and among the
                    Company, Geac Computers, Inc., Geac and David King.

         (g)        Not Applicable.

         (h)        Not Applicable.

ITEM 13. INFORMATION REQUIRED BY SCHEDULE 13E-3.

         Not Applicable.

                                    SIGNATURE

After due 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.

                                               GEAC COMPUTER CORPORATION LIMITED

                                               /s/  Charles S. Jones
                                               --------------------------------
                                               By:  Charles S. Jones
                                               Its: Chairman


                                               CONDUCTOR ACQUISITION CORP.

                                               /s/  Charles S. Jones
                                               --------------------------------
                                               By:  Charles S. Jones
                                               Its: Chairman




Date:  July 1, 2003


                                      -4-






                                INDEX TO EXHIBITS

<Table>
<Caption>
  EXHIBIT NUMBER  DESCRIPTION
  --------------  -----------
               
     (a)(1)(A)    Offer to Purchase, dated July 1, 2003.

     (a)(1)(B)    Letter of Transmittal.

     (a)(1)(C)    Notice of Guaranteed Delivery.

     (a)(1)(D)    Letter to Brokers, Dealers, Banks, Trust Companies and other
                  Nominees.

     (a)(1)(E)    Letter to Clients for use by Brokers, Dealers, Banks, Trust
                  Companies and other Nominees.

     (a)(1)(F)    Press Release dated July 1, 2003.


     (a)(1)(G)    Summary Advertisement, published in the New York Times on
                  July 1, 2003.


     (b)          Not Applicable.

     (c)          Not Applicable.

     (d)(1)       Confidentiality Agreement dated April 24, 2003 between Geac
                  and the Company.

     (d)(2)       Confidentiality Agreement effective May 1, 2003 between Geac
                  and the Company.

     (d)(3)       Agreement and Plan of Merger, dated as of June 22, 2003, by
                  and among Geac, Purchaser and the Company.

     (d)(4)       Voting and Tender Agreement, dated as of June 22, 2003, by and
                  among Geac, Purchaser and Dennis G. Ganster.

     (d)(5)       Voting and Tender Agreement, dated as of June 22, 2003, by and
                  among Geac, Purchaser and each of Codec Systems Limited and
                  Anthony Stafford.

     (d)(6)       Employment agreement dated June 19, 2003 by and among the
                  Company, Geac Computers, Inc., Geac and Brian Hartlen.

     (d)(7)       Employment agreement dated June 19, 2003 by and among the
                  Company, Geac Computers, Inc., Geac and David King.

     (g)          Not Applicable.

     (h)          Not Applicable.
</Table>

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