<Page>
________________________________________________________________________________

                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549

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

                                 FORM 10-K/A
              ANNUAL REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE
                        SECURITIES EXCHANGE ACT OF 1934

                  FOR THE FISCAL YEAR ENDED DECEMBER 31, 2000
                         COMMISSION FILE NUMBER 0-23611
                              -------------------

                                DSET CORPORATION
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)

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

<Table>
<S>                                            <C>
                  NEW JERSEY                                     22-3000022
       (STATE OR OTHER JURISDICTION OF              (I.R.S. EMPLOYER IDENTIFICATION NO.)
        INCORPORATION OR ORGANIZATION)

1160 U.S. HIGHWAY 22, BRIDGEWATER, NEW JERSEY                      08807
   (ADDRESS OF PRINCIPAL EXECUTIVE OFFICES)                      (ZIP CODE)
</Table>

       REGISTRANT'S TELEPHONE NUMBER, INCLUDING AREA CODE: (908) 526-7500

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

          SECURITIES REGISTERED PURSUANT TO SECTION 12(b) OF THE ACT:

<Table>
<Caption>
                                                           NAME OF EACH EXCHANGE
             TITLE OF EACH CLASS                            ON WHICH REGISTERED
             -------------------                            -------------------
<S>                                            <C>
                    None
</Table>

          SECURITIES REGISTERED PURSUANT TO SECTION 12(g) OF THE ACT:
                           Common Stock, no par value
                                (Title of Class)

    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/A or any
amendment to this Form 10-K/A.  [ ]

    State the aggregate market value of the voting common stock held by
non-affiliates of the registrant: $24,712,515 at March 1, 2001 based on the last
sales price on that date.

    Indicate the number of shares outstanding of each of the registrant's
classes of common stock, as of March 1, 2001:

<Table>
<Caption>
                    CLASS                                     NUMBER OF SHARES
                    -----                                     ----------------
<S>                                            <C>
          Common Stock, no par value                             11,629,419
</Table>

    The following documents are incorporated by reference into the Annual Report
on Form 10-K/A: Portions of the registrant's definitive Proxy Statement for its
2001 Annual Meeting of Shareholders are incorporated by reference into Part III
of this Report.

________________________________________________________________________________



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                                EXPLANATORY NOTE

The Registrant hereby further amends its Annual Report on Form 10-K for the
period ending December 31, 2000 and as previously amended on December 11, 2001
with the filing of its Form 10-K/A, solely to correct a clerical error on the
page thereof entitled "Report of Independent Accountants." Such Report of
Independent Accountants should have reflected a location of "New York, New York"
and a date of "December 11, 2001." A revised "Report of Independent
Accountants," reflecting the corrected location and date, is included herein.


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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 this 19th day of
December, 2001.

                                                     DSET CORPORATION

                                          By:     /s/ WILLIAM P. MCHALE, JR.
                                              ..................................
                                                   WILLIAM P. MCHALE, JR.,
                                                PRESIDENT AND CHIEF EXECUTIVE
                                                           OFFICER

    Pursuant to the requirements of the Securities and Exchange Act of 1934,
this report has been signed below by the following persons on behalf of the
registrant and in the capacities and on the dates indicated.

<Table>
<Caption>
                SIGNATURE                                    TITLE                         DATE
                ---------                                    -----                         ----
<S>                                         <C>                                       <C>
        /s/ WILLIAM P. MCHALE, JR.          President, Chief Executive Officer and
 .........................................    Chairman of the Board of Directors
         (WILLIAM P. MCHALE, JR.)             (Principal Executive Officer)            December 19, 2001

           /s/ BRUCE M. CROWELL             Chief Financial Officer (Principal
 .........................................    Financial and Accounting Officer)
            (BRUCE M. CROWELL)                                                         December 19, 2001

           /s/ ANDREW D. LIPMAN             Director
 .........................................
            (ANDREW D. LIPMAN)                                                         December 19, 2001

            /s/ C. DANIEL YOST              Director
 .........................................
             (C. DANIEL YOST)                                                          December 19, 2001

          /s/ JACOB J. GOLDBERG             Director
 .........................................
           (JACOB J. GOLDBERG)                                                         December 19, 2001
</Table>






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                       REPORT OF INDEPENDENT ACCOUNTANTS

To the Board of Directors and Shareholders of DSET Corporation:

    Our audits of the consolidated financial statements referred to in our
report dated March 27, 2001, which appears in this Annual Report on Form 10-K/A,
also included an audit of the financial statement schedule listed in Item 14(a)
(2) of this Form 10-K/A. In our opinion, this financial statement schedule
presents fairly, in all material respects, the information set forth therein
when read in conjunction with the related consolidated financial statements.

                                       /s/ PricewaterhouseCoopers LLP

New York, New York
December 11, 2001