<PAGE>

NEITHER THE SECURITIES REPRESENTED HEREBY NOR THE SECURITIES ISSUABLE UPON THE
EXERCISE HEREOF HAVE BEEN REGISTERED UNDER THE SECURITIES ACT OF 1933, AS
AMENDED (THE "SECURITIES ACT"), OR ANY STATE SECURITIES LAWS AND MAY NOT BE
OFFERED, SOLD, PLEDGED, ASSIGNED, OR OTHERWISE TRANSFERRED UNLESS (1) A
REGISTRATION STATEMENT WITH RESPECT THERETO IS EFFECTIVE UNDER THE SECURITIES
ACT AND ANY APPLICABLE STATE SECURITIES LAWS, OR (2) THE COMPANY RECEIVES AN
OPINION OF COUNSEL TO THE HOLDER OF THIS WARRANT OR SUCH SECURITIES, WHICH
COUNSEL AND OPINION ARE REASONABLY SATISFACTORY TO THE COMPANY, THAT THIS
WARRANT OR SUCH SECURITIES, AS APPLICABLE, MAY BE OFFERED, SOLD, PLEDGED,
ASSIGNED, OR OTHERWISE TRANSFERRED IN THE MANNER CONTEMPLATED WITHOUT AN
EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR APPLICABLE STATE
SECURITIES LAWS.



         THE TRANSFER OF THIS WARRANT IS RESTRICTED AS DESCRIBED HEREIN.



                               CLAIMSNET.COM INC.


                            WARRANTS FOR THE PURCHASE
                                       OF
            600,000 SHARES OF COMMON STOCK, PAR VALUE $.001 PER SHARE
            -------

NO. W- 2003-8                                                       JUNE 3, 2003
       ------

         THIS CERTIFIES that, for value received, ALFRED DUBACH (together with
all permitted assigns, the "Holder") is entitled to subscribe for, and purchase
from, CLAIMSNET.COM, INC., a Delaware corporation (the "Company"), upon the
terms and conditions set forth herein 600,000 shares of common stock, par value
$.001 per share, of the Company. This Warrant is exercisable at an exercise
price per share equal to $0.15 per share; provided, however, that upon the
occurrence of any of the events specified in Section 5 hereof, the rights
granted by this Warrant, including the number of shares of Common Stock to be
received upon such exercise, shall be adjusted as therein specified.

         This Warrant, together with warrants issuable upon the transfer hereof,
are hereinafter referred to as the Warrants. Each share of Common Stock issuable
upon the exercise hereof shall be hereinafter referred to as a "Warrant Share".

<PAGE>

         SECTION 1          EXERCISE OF WARRANT AND PAYMENT FOR SHARES.
                            -------------------------------------------

                  The Warrants shall become exercisable according to the
following vesting schedule:

         ------------------------------------------ ----------------------------
            Period of Warrant Holder's Continuous
         Relationship With the Company or Affiliate   Portion of Total Warrant
                From the Date the Warrant is                  Which is
                          Granted                           Exercisable
                          -------                           -----------
         ------------------------------------------ ----------------------------
                           1 year                               50%
         ------------------------------------------ ----------------------------
                           2 years                             100%
         ------------------------------------------ ----------------------------

         Subject to the vesting schedule described above, this Warrant may be
exercised during the period commencing from the date of grant and ending on the
earlier of (i) ten years from the date of grant, (ii) immediately upon
termination of the Holder for cause, which shall mean dismissal for dishonesty,
conviction or confession of a crime punishable by law (except minor violations),
fraud, misconduct, or disclosure of confidential information, (iii) three months
after cessation of the Holder's relationship with the Company or an Affiliate
thereof, other than for cause unless cessation is due to death or total
disability, in which case the Warrant shall terminate twelve months after
cessation of such relationship, or (iv) five years after cessation of the
Holder's relationship with the Company or an Affiliate thereof in the event of a
Reclassification, Reorganization, or Merger event, as defined in section 6,
provided, that the Holder's employment is terminated within twelve months
following the date of such Reclassification, Reorganization, or Merger event
(the "Exercise Period").

         This Warrant may be exercised during the Exercise Period, either in
whole or in part, by the surrender of this Warrant (with the election at the end
hereof duly executed) to the Company at its office at 12801 N. Central
Expressway, Suite 1515, Dallas, Texas 75243, or at such other place as is
designated in writing by the Company, together with a certified or bank
cashier's check payable to the order of the Company in an amount equal to the
product of the Exercise Price and the number of Warrant Shares for which this
Warrant is being exercised.

         The Warrant may be exercised by the delivery of:

                  (a) Cash, personal check (unless at the time of exercise the
Board of Directors determines otherwise), or bank certified or cashier's checks;

                  (b) Unless the Board of Directors in their sole discretion
determine otherwise, shares of the capital stock of the Company held by you
having a fair market value at the time of exercise, as determined in good faith
by the Board of Directors, equal to the exercise price;

                  (c) Unless the Board of Directors in their sole discretion
determine otherwise, a properly executed Notice of Exercise, together with
instructions to the Company to withhold from the shares that would otherwise be


                                      - 2 -
<PAGE>

issued upon exercise that number of shares having a fair market value equal to
the option exercise price; or

                  (d) Unless the Board of Directors in their sole discretion
determine otherwise, a properly executed Notice of Exercise, together with
irrevocable instructions to a broker to promptly deliver to the Company the
amount of sale or loan proceeds to pay the exercise price.

         SECTION 2          RIGHTS UPON EXERCISE; DELIVERY OF SECURITIES.
                            ---------------------------------------------

                  Upon each exercise of the Holder's rights to purchase Warrant
Shares, the Holder shall be deemed to be the holder of record of the Warrant
Shares, notwithstanding that the transfer books of the Company shall then be
closed or certificates representing the Warrant Shares with respect to which
this Warrant was exercised shall not then have been actually delivered to the
Holder. As soon as practicable after each such exercise of this Warrant, the
Company shall issue and deliver to the Holder a certificate or certificates
representing the Warrant Shares issuable upon such exercise, registered in the
name of the Holder or its designee. If this Warrant should be exercised in part
only, the Company shall, upon surrender of this Warrant for cancellation,
execute and deliver a Warrant evidencing the right of the Holder to purchase the
balance of the aggregate number of Warrant Shares purchasable hereunder as to
which this Warrant has not been exercised or assigned.

         SECTION 3          TRANSFERABILITY.
                            ----------------

                  Except as otherwise expressly provided herein, this Warrant
shall not be transferable. This Warrant may be exchanged, at the option of the
Holder thereof, for another Warrant, or other Warrants of different
denominations, of like tenor and representing in the aggregate the right to
purchase a like number of Warrant Shares (or portions thereof), upon surrender
to the Company or its duly authorized agent.

         SECTION 4          RESERVATION OF SHARES.
                            ----------------------

                  The Company shall at all times reserve and keep available out
of its authorized and unissued Common Stock, solely for the purpose of providing
for the exercise of the Warrants, such number of shares of Common Stock as
shall, from time to time, be sufficient therefor. The Company represents that
all shares of Common Stock issuable upon exercise of this Warrant are duly
authorized and, upon receipt by the Company of the full payment for such Warrant
Shares, will be validly issued, fully paid, and nonassessable, without any
personal liability attaching to the ownership thereof and will not be issued in
violation of any preemptive or similar rights of stockholders.

         SECTION 5          ANTIDILUTION.
                            -------------

                  (a) In the event that the Company shall at any time after the
Initial Exercise Date: (i) declare a dividend on the outstanding Common Stock
payable in shares of its capital stock; (ii) subdivide the outstanding Common
Stock; (iii) combine the outstanding Common Stock into a smaller number of


                                      - 3 -
<PAGE>

shares; or (iv) issue any shares of its capital stock by reclassification of the
Common Stock (including any such reclassification in connection with a
consolidation or merger in which the Company is the continuing corporation),
then, in each case, the Exercise Price per Warrant Share in effect at the time
of the record date for the determination of stockholders entitled to receive
such dividend or distribution or of the effective date of such subdivision,
combination, or reclassification shall be adjusted so that it shall equal the
price determined by multiplying such Exercise Price by a fraction, the numerator
of which shall be the number of shares of Common Stock outstanding immediately
prior to such action, and the denominator of which shall be the number of shares
of Common Stock outstanding after giving effect to such action. Such adjustment
shall be made successively whenever any event listed above shall occur and shall
become effective at the close of business on such record date or at the close of
business on the date immediately preceding such effective date, as applicable.

                  (b) All calculations under this Section 5 shall be made to the
nearest cent or to the nearest one-hundredth of a share, as the case may be.

                  (c) In any case in which this Section 5 shall require that an
adjustment in the number of Warrant Shares be made effective as of a record date
for a specified event, the Company may elect to defer, until the occurrence of
such event, issuing to the Holder, if the Holder exercised this Warrant after
such record date, the Warrant Shares, if any, issuable upon such exercise over
and above the number of Warrant Shares issuable upon such exercise on the basis
of the number of shares of Common Stock in effect prior to such adjustment;
provided, however, that the Company shall deliver to the Holder a due bill or
other appropriate instrument evidencing the Holder's right to receive such
additional shares of Common Stock upon the occurrence of the event requiring
such adjustment.

                  (d) Whenever there shall be an adjustment as provided in this
Section 5, the Company shall within 15 days thereafter cause written notice
thereof to be sent by registered mail, postage prepaid, to the Holder, at its
address as it shall appear in the books and records of the Company, which notice
shall be accompanied by an officer's certificate setting forth the number of
Warrant Shares issuable and the Exercise Price thereof after such adjustment and
setting forth a brief statement of the facts requiring such adjustment and the
computation thereof, which officer's certificate shall be conclusive evidence of
the correctness of any such adjustment absent manifest error.

                  (e) The Company shall not be required to issue fractions of
shares of Common Stock or other capital stock of the Company upon the exercise
of this Warrant. If any fraction of a share of Common Stock would be issuable on
the exercise of this Warrant (or specified portions thereof), the Company shall
pay lieu of such fraction an amount in cash equal to the same fraction of the
average closing sale price (or average of the closing bid and asked prices, if
closing sale price is not available) of Common Stock for the 10 trading days
ending on and including the date of exercise of this Warrant.

                  (f) No adjustment in the Exercise Price per Warrant Share
shall be required if such adjustment is less than $.05; provided, however, that


                                     - 4 -
<PAGE>

any adjustments which by reason of this Section 5 are not required to be made
shall be carried forward and taken into account in any subsequent adjustment.

                  (g) Whenever the Exercise Price payable upon exercise of this
Warrant is adjusted pursuant to subsection (a) above, the number of Warrant
Shares issuable upon exercise of this Warrant shall simultaneously be adjusted
by multiplying the number of Warrant Shares theretofore issuable upon exercise
of this Warrant by the Exercise Price in effect on the date hereof and dividing
the product so obtained by the Exercise Price, as adjusted.

         SECTION 6          RECLASSIFICATION; REORGANIZATION; MERGER.
                            -----------------------------------------

                  (a) In case of any capital reorganization, other than in the
cases referred to in Section 5(a) hereof, or the consolidation or merger of the
Company with or into another corporation (other than a merger or consolidation
in which the Company is the continuing corporation and which does not result in
any reclassification of the outstanding shares of Common Stock or the conversion
of such outstanding shares of Common Stock into shares of other stock or other
securities or property), or in the case of any sale, lease, or conveyance to
another corporation of the property and assets of any nature of the Company as
an entirety or substantially as an entirety (such actions being hereinafter
collectively referred to as "Reorganizations"), there shall thereafter be
deliverable upon exercise of this Warrant (in lieu of the number of Warrant
Shares theretofore deliverable) the number of shares of stock or other
securities or property to which a holder of the respective number of Warrant
Shares which would otherwise have been deliverable upon the exercise of this
Warrant would have been entitled upon such Reorganization if this Warrant had
been exercised in full immediately prior to such Reorganization. In case of any
Reorganization, appropriate adjustment, as determined in good faith by the Board
of Directors of the Company, shall be made in the application of the provisions
herein set forth with respect to the rights and interests of the Holder so that
the provisions set forth herein shall thereafter be applicable, as nearly as
possible, in relation to any shares or other property thereafter deliverable
upon exercise of this Warrant. Any such adjustment shall be made by, and set
forth in, a supplemental agreement between the Company, or any successor
thereto, and the Holder, with respect to this Warrant, and shall for all
purposes hereof conclusively be deemed to be an appropriate adjustment. The
Company shall not effect any such Reorganization unless, upon or prior to the
consummation thereof, the successor corporation, or if the Company shall be the
surviving corporation in any such Reorganization and is not the issuer of the
shares of stock or other securities or property to be delivered to holders of
shares of the Common Stock outstanding at the effective time thereof, then such
issuer, shall assume by written instrument the obligation to deliver to the
Holder such shares of stock, securities, cash, or other property as such Holder
shall be entitled to purchase in accordance with the foregoing provisions. In
the event of sale, lease, or conveyance or other transfer of all or
substantially all of the assets of the Company as part of a plan for liquidation
of the Company, all rights to exercise this Warrant shall terminate 30 days
after the Company gives written notice to the Holder that such sale or
conveyance or other transfer has been consummated.

                  (b) In case of any reclassification or change of the shares of
Common Stock issuable upon exercise of this Warrant (other than a change in par
value or from a specified par value to no par value, or as a result of a
subdivision or combination, but including any change in the shares into two or
more classes or series of shares), or in case of any consolidation or merger of


                                     - 5 -
<PAGE>

another corporation into the Company in which the Company is the continuing
corporation and in which there is a reclassification or change (including a
change to the right to receive cash or other property) of the shares of Common
Stock (other than a change in par value, or from no par value to a specified par
value, or as a result of a subdivision or combination, but including any change
in the shares into two or more classes or series of shares), the Holder or
holders of this Warrant shall have the right thereafter to receive upon exercise
of this Warrant solely the kind and amount of shares of stock and other
securities, property, cash, or any combination thereof receivable upon such
reclassification, change, consolidation, or merger by a holder of the number of
Warrant Shares for which this Warrant might have been exercised immediately
prior to such reclassification, change, consolidation, or merger. Thereafter,
appropriate provision shall be made for adjustments which shall be as nearly
equivalent as practicable to the adjustments in Section 5.

                  (c) The above provisions of this Section 6 shall similarly
apply to successive reclassifications and changes of shares of Common Stock and
to successive consolidations, mergers, sales, leases, or conveyances.

         SECTION 7          NOTICE OF CERTAIN EVENTS.
                            -------------------------

                  In case at any time the Company shall propose:

         (a) to pay any dividend or make any distribution on shares of Common
Stock in shares of Common Stock or make any other distribution (other than
regularly scheduled cash dividends which are not in a greater amount per share
than the most recent such cash dividend) to all holders of Common Stock; or
         (b) to issue any rights, warrants, or other securities to all holders
of Common Stock entitling them to purchase any additional shares of Common Stock
or any other rights, warrants, or other securities; or

         (c) to effect any reclassification or change of outstanding shares of
Common Stock or any consolidation, merger, sale, lease, or conveyance of
property, as described in Section 6; or

         (d) to effect any liquidation, dissolution, or winding-up of the
Company; or

         (e) to take any other action which would cause an adjustment to the
Exercise Price per Warrant Share;

then, and in any one or more of such cases, the Company shall give written
notice thereof by registered mail, postage prepaid, to the Holder at the
Holder's address as it shall appear in the Warrant Register, mailed at least 15
days prior to: (i) the date as of which the holders of record of shares of
Common Stock to be entitled to receive any such dividend, distribution, rights,
warrants, or other securities are to be determined; (ii) the date on which any
such reclassification, change of outstanding shares of Common Stock,
consolidation, merger, sale, lease, conveyance of property, liquidation,
dissolution, or winding-up is expected to become effective and the date as of
which it is expected that holders of record of shares of Common Stock shall be
entitled to exchange their shares for securities or other property, if any,


                                     - 6 -
<PAGE>

deliverable upon such reclassification, change of outstanding shares,
consolidation, merger, sale, lease, conveyance of property, liquidation,
dissolution, or winding-up; or (iii) the date of such action which would require
an adjustment to the Exercise Price per Warrant Share.

         SECTION 8          CHARGES AND TAXES.
                            ------------------

                  The issuance of any shares or other securities upon the
exercise of this Warrant and the delivery of certificates or other instruments
representing such shares or other securities shall be made without charge to the
Holder for any tax or other charge in respect of such issuance. The Company
shall not, however, be required to pay any tax which may be payable in respect
of any transfer involved in the issue and delivery of any certificate in a name
other than that of the Holder and the Company shall not be required to issue or
deliver any such certificate unless and until the person or persons requesting
the issue thereof shall have paid to the Company the amount of such tax or shall
have established to the satisfaction of the Company that such tax has been paid.

         SECTION 9          PERIODIC REPORTS.
                            -----------------

                  The Company agrees that until all the Warrant Shares shall
have been sold pursuant to Rule 144 under the Securities Act or a Registration
Statement under the Securities Act, it shall keep current in filing all reports,
statements, and other materials required to be filed with the Commission to
permit holders of the Warrant Shares to sell such securities under Rule 144
under the Securities Act.

         SECTION 10         LEGEND.
                            -------

                  Until sold pursuant to the provisions of Rule 144 or otherwise
registered under the Securities Act, the Warrant Shares issued on exercise of
the Warrants shall be subject to a stop transfer order and the certificate or
certificates representing the Warrant Shares shall bear the following legend:

THE SECURITIES REPRESENTED HEREBY HAVE NOT BEEN REGISTERED UNDER THE SECURITIES
ACT OF 1933, AS AMENDED (THE "SECURITIES ACT"), OR ANY STATE SECURITIES LAWS AND
MAY NOT BE OFFERED, SOLD, PLEDGED, ASSIGNED, OR OTHERWISE TRANSFERRED UNLESS (1)
A REGISTRATION STATEMENT WITH RESPECT THERETO IS EFFECTIVE UNDER THE SECURITIES
ACT AND ANY APPLICABLE STATE SECURITIES LAWS, OR (2) THE COMPANY RECEIVES AN
OPINION OF COUNSEL TO THE HOLDER OF THE SECURITIES, WHICH COUNSEL AND OPINION
ARE REASONABLY SATISFACTORY TO THE COMPANY, THAT SUCH SECURITIES MAY BE OFFERED,
SOLD, PLEDGED, ASSIGNED, OR OTHERWISE TRANSFERRED IN THE MANNER CONTEMPLATED
WITHOUT AN EFFECTIVE REGISTRATION STATEMENT UNDER THE SECURITIES ACT OR
APPLICABLE STATE SECURITIES LAWS.

         SECTION 11         LOSS; THEFT; DESTRUCTION; MUTILATION.
                            -------------------------------------

                                     - 7 -
<PAGE>

                  Upon receipt of evidence satisfactory to the Company of the
loss, theft, destruction, or mutilation of any Warrant (and upon surrender of
any Warrant if mutilated), and upon receipt by the Company of reasonably
satisfactory indemnification, the Company shall execute and deliver to the
Holder thereof a new Warrant of like date, tenor, and denomination.

         SECTION 12         STOCKHOLDER RIGHTS.
                            -------------------

                  The Holder of any Warrant shall not have, solely on account of
such status, any rights of a stockholder of the Company, either at law or in
equity, or to any notice of meetings of stockholders or of any other proceedings
of the Company, except as provided in this Warrant.

         SECTION 13         GOVERNING LAW.
                            --------------

                  This Warrant shall be construed in accordance with the laws of
the State of New York applicable to contracts made and performed within such
State, without regard to principles of conflicts of law.


         IN WITNESS WHEREOF, the Company has executed this Warrant as of the
date first above written.

                                         CLAIMSNET.COM INC.


                                         BY: __________________________
                                             NAME:   DON CROSBIE
                                             TITLE:  CHIEF EXECUTIVE OFFICER

                                     - 8 -
<PAGE>

                               FORM OF ASSIGNMENT

       (To be executed by the registered holder if such holder desires to
                         transfer the attached Warrant.)

         FOR VALUE RECEIVED,  ______________________  hereby sells, assigns, and
transfers unto _________________ a Warrant to purchase __________ shares of
Common Stock, without par value, of Claimsnet.com inc., a Delaware corporation
(the "Company"), and does hereby irrevocably constitute and appoint ___________
attorney to transfer such Warrant on the books of the Company, with full power
of substitution.

Dated: _________________

                                                Signature_______________________

                                     NOTICE

         The signature on the foregoing Assignment must correspond to the name
as written upon the face of this Warrant in every particular, without alteration
or enlargement or any change whatsoever.

                                     - 9 -
<PAGE>

                              ELECTION TO EXERCISE

To:      Claimsnet.com inc.



         The undersigned hereby exercises his, her, or its rights to purchase
shares of Common Stock, par value $.001 per share ("the Common Stock"), of
Claimsnet.com inc., a Delaware corporation (the "Company"), covered by the
within Warrant and tenders payment herewith in the amount of $_____ in
accordance with the terms thereof, and requests that certificates for the
securities constituting such shares of Common Stock be issued in the name of,
and delivered to:








     (Print Name, Address, and Social Security or Tax Identification Number)

and, if such number of shares of Common Stock shall not constitute all such
shares of Common Stock covered by the within Warrant, that a new Warrant for the
balance of the shares of Common Stock covered by the within Warrant shall be
registered in the name of, and delivered to, the undersigned at the address
stated below.


Dated: __________________                   Name________________________
                                                       (Print)

Address:



                                                ________________________
                                                     (Signature)

                                     - 10 -