<PAGE>
                                 UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

                                   FORM 10-K/A


(Mark One)
[X]  ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE
     ACT OF 1934
     For the fiscal year ended December 31, 2002

                                       OR

[ ]  TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES
     EXCHANGE ACT OF 1934
     For the transition period from             to                           .

     Commission file number 001-13672

                            The Commerce Group, Inc.
             (Exact name of registrant as specified in its charter)

            Massachusetts                                 04-2599931
    (State or other jurisdiction               (IRS Employer Identification No.)
          of incorporation)

            211 Main Street                                 01570
         Webster, Massachusetts                          (Zip Code)
  (Address of principal executive offices)

       Registrant's telephone number, including area code: (508) 943-9000

           Securities registered pursuant to Section 12(b) of the Act:

                                                     Name of each Exchange
        Title of each Class                           on Which Registered
        -------------------                          ---------------------
Common Stock, $.50 Par Value Per Share              New York Stock Exchange

           Securities registered pursuant to Section 12(g) of the Act:
                                      None

     Indicate by check mark whether the registrant (1) has filed all reports
required to be filed by Section 13 or 15(d) of the Securities Exchange Act of
1934 during the preceding 12 months (or for such shorter period that the
registrant was required to file such reports), and (2) has been subject to such
filing requirements for the past 90 days. Yes [X] No [ ]

     Indicate by check mark if disclosure of delinquent filers pursuant to Item
405 of Regulation S-K is not contained herein, and will not be contained, to the
best of registrant's knowledge, in definitive proxy or information statements
incorporated by reference in Part III of this Form 10-K or any amendment to this
Form 10-K. [ ]

     Indicate by check mark whether the registrant is an accelerated filer (as
defined in Exchange Act Rule 12b-2). Yes [X] No [ ]

     The aggregate market value of the common stock held by non-affiliates of
the registrant, computed by reference to the price at which the common stock was
last sold, as of June 30, 2003, was $786,766,166.



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ITEM 5. MARKET FOR REGISTRANT'S COMMON STOCK AND RELATED STOCKHOLDER MATTERS

     The Company has granted stock options to eligible agents of American
Commerce. The following table provides a summary of those grants.

<TABLE>
<CAPTION>

  GRANT         NUMBER OF           DATE        EXPIRATION
  DATE       UNDERLYING SHARES   EXERCISABLE       DATE        EXERCISE PRICE
  ----       -----------------   -----------    ----------     --------------
<S>             <C>             <C>            <C>            <C>

11/29/99          1,872,380       11/29/04       11/29/09          $36.32
07/31/00             25,000        7/31/05        7/31/10          $34.04
07/31/01            225,000        7/31/06        7/31/11          $42.85
07/31/02            475,000        7/31/07        7/31/12          $49.50

</TABLE>

     No cash consideration was received by the Company in exchange for the
options. The purpose of the options is to provide an incentive for the agents to
maintain their existing business volume with American Commerce. Additional
options are granted based on the year-over-year increase in the volume of agency
business written with American Commerce.

     The options have been offered and sold pursuant to Securities Act Rule 506.
Neither the Company nor any person acting on its behalf has offered or sold the
options by any form of general solicitation or general advertising, and the
Company has exercised reasonable care to assure that none of the recipients is
an underwriter within the meaning of Section 2(11) of the Securities Act. Based
upon representations from the recipients, the Company has reason to believe that
not more than one of the recipients was not an accredited investor, as defined
in Securities Act Rule 501.

     The right of the recipient to exercise these options is contingent upon the
average volume of other-than-Massachusetts private passenger automobile and
homeowners direct written premiums placed and maintained with American Commerce
for a five-year period specified in each option agreement. If qualified, the
recipient may purchase the Company's common stock at the exercise price for a
period of five years beginning five years after the date of the grant (the
"Confirmation Date"). Unexercised options terminate not later than ten years
after the date of the grant (the "Expiration Date"). The options may be
exercised only by withholding option shares to pay the exercise price.

     The Company provided "put rights" to the holders of the options granted in
1999. These put rights permit the option holders to require the Company to
purchase the options, at any time from and after the Confirmation Date through
and including the Expiration Date, at a price of $3.68 per share, which is the
difference between the exercise price per option and $40.00. Our total liability
under the put rights, assuming that the options become fully exercisable, would
be $6.9 million.

     For the other information required by this Item, please refer to
"Management's Discussion and Analysis of Financial Condition and Results of
Operations--Common Stock Price and Dividend Information."


ITEM 15. EXHIBITS, FINANCIAL STATEMENT SCHEDULES AND REPORTS ON FORM 8-K

A.   (1)  The financial statements and notes to financial statements are filed
          as part of this report in "Part II Item 8".

     (2)  The financial statement schedules are listed in the Index to
          Consolidated Financial Statement Schedules.

     (3)  The exhibits are listed in the Index to Exhibits.

B.   No reports on Form 8-K were filed during the quarter ended December 31,
     2002.
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                                   SIGNATURES

     Pursuant to the requirements of Section 13 or 15(d) of the Securities
Exchange Act of 1934, the registrant has duly caused this report to be signed on
its behalf by the undersigned, thereunto duly authorized.

Dated: September 29, 2003

                                          THE COMMERCE GROUP, INC.

                                          By:/s/ Arthur J. Remillard, Jr.
                                             --------------------------------
                                             Arthur J. Remillard, Jr.
                                             President, Chief Executive Officer,
                                             and Chairman of the Board


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                 THE COMMERCE GROUP, INC. AND SUBSIDIARIES
                           INDEX TO EXHIBITS(A)

<TABLE>
<CAPTION>

EXHIBIT
NUMBER                     TITLE
-------                    -----
<S>        <C>

  3.1       Articles of Organization, as amended (B)

  3.2       By-Laws (B)

  4         Stock Certificate (B)

 10.8*      1994 Management Incentive Plan as amended (C)

 10.18*     Form of Non-Qualified Stock Option Agreement (D)

 10.19*     Form of Incentive Stock Option Agreement (D)

 10.20*     Form of Non-Qualified Stock Option Agreement (D)

 10.21*     Form of Stock Option Agreement (D)

 10.23*     Form of Book Value Award Agreement (E)

 10.24      Reinsurance Agreement with Employers Reinsurance Corporation(F)

 10.25*     2002 Amended & Restated Incentive Compensation Plan (G)

 10.26      ACIC Agent Growth Option Agreement (G)

 10.27      Form of AAA Marketing Agreement

 10.28      Form of AAA Service Agreement

 21.1       Subsidiaries of the Registrant (G)

 31.1       Rule 13a-14(a)/15d-14(a) Certification

 31.2       Rule 13a-14(a)/15d-14(a) Certification

</TABLE>

(A)  Exhibits other than those listed are omitted because they are not required
     or are not applicable. Copies of exhibits are available without charge by
     writing to the Assistant to the President at 211 Main Street, Webster, MA
     01570.

(B)  Incorporated herein by reference to the exhibit with the same exhibit
     number, filed as an exhibit to the Registrant's Registration Statement on
     Form S-18 (No. 33-12533-B).

(C)  Incorporated herein by reference to the exhibit with the same exhibit
     number, filed as an exhibit to the Registrant's Form 10-Q for the period
     ended September 30, 1997.

(D)  Incorporated herein by reference to the exhibit with the same exhibit
     number, filed as an exhibit to the Registrant's Form 10-K for the year
     ended December 31, 1999.

(E)  Incorporated herein by reference to the exhibit with the same exhibit
     number, filed as an exhibit to the Registrant's Form 10-Q for the period
     ended June 30, 2002.

(F)  Incorporated herein by reference to the exhibit with the same exhibit
     number, filed as an exhibit to the Registrant's Form 10-Q for the period
     ended September 30, 2002.

(G)  Filed as an exhibit to the Registrant's Form 10-K for the year ended
     December 31, 2002.

* Denotes management contract or compensation plan or arrangement.