<PAGE>

                                                                  EXHIBIT 10.2

                                 FULL RECOURSE
                                PROMISSORY NOTE

$19,350.41                                              May 22, 1998
                                                        Walnut Creek, California

     FOR VALUE RECEIVED, James Weaver ("MAKER"), an individual, promises to pay
Tier Technologies, Inc., a California corporation ("HOLDER"), or order, at 1350
Treat Boulevard, Suite 250, Walnut Creek, California or such other place as
Holder may from time to time designate, in lawful money of the United States,
the principal sum of nineteen thousand three hundred fifty dollars and forty-one
cents ($19,350.41), plus interest thereon from the date of issuance until paid
in full, as set forth below.

     1.   Interest.  Interest on the principal sum of this Note shall accrue at
          --------                                                             
          the rate of  5.50% per annum, compounded annually, based on a 365-day
          year and the actual number of days elapsed.  Interest shall be payable
          by Maker on a quarterly basis and shall not be forgiven.

     2.   Payments/Forgiveness. The entire principal sum and all accrued but
          --------------------
          unpaid interest and any other sums payable hereunder shall be due and
          payable in full on May 22, 1999; provided, however, that the entire
          principal sum advanced shall be forgiven by Holder should Maker remain
          employed by the Company on May 22, 1999 (and without interruption from
          the date of this Note). In the event Maker's employment with the
          Company terminates prior to May 22, 1999, because Maker has
          voluntarily ceased his employment, the entire principal sum and all
          accrued but unpaid interest and any other sums payable hereunder shall
          be immediately due and payable. In the event that Maker's employment
          is terminated by the Company for cause at any time during Maker's
          employment, the entire principal sum and all accrued but unpaid
          interest and any other sums payable hereunder shall also be
          immediately due and payable.

     3.   Prepayment.  This Note may be prepaid in whole or in part, at any
          ----------                                                       
          time, without penalty or premium.

     4.   Application of Payments.  All payments received by Holder shall be
          -----------------------                                           
          applied first to accrued interest, then to other charges due with
          respect to this Note, and then to then-unpaid principal balance.

     6.   Default and Remedies.
          -------------------- 

          a.   Default.  Maker will be in default under this Note if (i) Maker
               -------                                                        
               fails to make a payment of principal and/or interest hereunder
               when due, or (ii) Maker breaches any other covenant or agreement
               under this Note.

          b.   Remedies.  Upon Maker's default, Holder may (i) upon fifteen (15)
               --------                                                         
               days' written notice to Maker, declare the entire principal sum
               and all accrued and unpaid interest hereunder immediately due and
               payable and (ii) exercise any and all remedies provided under
               applicable law.  Maker 

                                       1
<PAGE>
 
               accepts and agrees that this Note is a full recourse Note and
               that Holder may exercise any and all remedies available to it
               under law.

     7.   Waivers.  Maker, and any endorsers or guarantors hereof, severally
          -------                                                           
          waive diligence, presentment, protest and demand and also notice of
          dishonor of this Note, and expressly agrees that this Note, or any
          payment hereunder, may be extended from time to time without notice,
          all without in any way affecting the liability of Maker or any
          endorsers or guarantors hereof.  No extension of time for the payment
          of this Note, or any installment hereof, agreed to by Holder with any
          person now or hereafter liable for the payment of this Note, shall
          affect the original liability of Maker under this Note, even if Maker
          is not a party to such agreement.  Holder may waive its right to
          require performance of or compliance with any term, covenant or
          condition of this Note only by express written waiver.

     8.   Miscellaneous.
          ------------- 

          a.   Maker shall pay all costs, including, without limitation,
               reasonable attorneys' fees and costs incurred by Holder in
               collecting the sums due hereunder,  whether or not any legal
               action is actually filed, litigated or prosecuted to judgment or
               award.  In the event of any action or legal proceeding concerning
               this Note or the enforcement of any rights hereunder, Holder
               shall be entitled to, in addition to any other relief to which
               Holder may be entitled, all legal and court costs and expenses,
               including reasonable attorneys' fees, incurred by Holder in
               connection with such action.

          b.   This Note may be modified only by a written agreement executed by
               Maker and Holder.

          c.   This Note shall be governed by California law.

          d.   The terms of this Note shall inure to the benefit of and bind
               Maker and Holder and their respective heirs, legal
               representatives and successors and assigns.

          e.   Time is of the essence with respect to all matters set forth in
               this Note.

          f.   If this Note is destroyed, lost or stolen, Maker will deliver a
               new Note to Holder on the same terms and conditions as this Note,
               with a notation of the unpaid principal and accrued and unpaid
               interest in substitution of the prior Note.  Holder shall furnish
               to Maker reasonable evidence that the Note was destroyed, lost or
               stolen and any security or indemnity that may be reasonably
               required by Maker in connection with the replacement of this
               Note.

          IN WITNESS WHEREOF, Maker has executed this Note as of the date and
          year first above written.

                                       2
<PAGE>
 
                                                Maker: /s/ James R. Weaver
                                                       -------------------------

                                       3