<PAGE>   1
                                                                 EXHIBIT 10.3(g)


                                   AGREEMENT

                                      for
                  SUPPLEMENTAL EXECUTIVE RETIREMENT BENEFITS

This Agreement is made this 1st day of December, 1996, between Blue Cross and
Blue Shield of Georgia, Inc. (the "Company") and Richard D. Shirk (the
"Executive").

                                    RECITALS

WHEREAS, Company desires to employ and retain the unique experience, ability,
and services of Executive as Company's President and Chief Executive Officer;
and

WHEREAS, Company desires to provide a nonqualified retirement benefit to
supplement the retirement income benefit provided to Executive under the
Non-Contributory Retirement Program for Certain Employees of Blue Cross and Blue
Shield of Georgia, Inc. (the "Qualified Plan"); and

WHEREAS, the terms and conditions of this Agreement have been duly approved and
authorized by the Compensation Committee of the Company's Board of Directors;

NOW, THEREFORE, in consideration of the mutual covenants set forth in this
Agreement, and of other good and valuable consideration which Company and
Executive have received and accept as sufficient, Company and Executive agree
as follows:

1.  AGREEMENT TERM

    The term of this Agreement shall coincide with the term of the Employment
    Agreement between Company and Executive. No termination of this Agreement
    shall have the effect of reducing benefits accrued by Executive prior to the
    date of such termination.

2.  BENEFIT ELIGIBILITY

    If Executive voluntarily terminates employment with Company without Good
    Reason before reaching age 55, Executive shall not be entitled to any
    benefits under this Agreement.  Executive becomes entitled to benefits
    under this Agreement upon any other termination from employment.



                                       1
<PAGE>   2

For purposes of this Agreement, Executive's employment is terminated for Good
Reason if the termination constitutes Good Reason under Executive's Employment
Agreement.

3.  AMOUNTS OF BENEFITS

    (a)  TERMINATION BEFORE AGE 55.  If Executive's employment is terminated
         before age 55, and Executive is otherwise eligible for a retirement
         benefit under Section 2 above, Executive shall be entitled to a
         monthly benefit, calculated as a single life annuity commencing at age
         55.  This monthly benefit shall equal --

         (1)  2 percent of Executive's Final Average Earnings; times

         (2)  Executive's Years of Credited Service; minus

         (3)  21 percent (which represents a reduction of 3 percent per year
              for each year that the benefit begins before age 62); minus

         (4)  the single life annuity Executive would be entitled to under the
              Qualified Plan at the time benefits commence under this
              Agreement; minus

         (5)  the Actuarial Equivalent value (as defined in Section 7(c) below)
              of Executive's age 62 benefits under the Social Security Act.

   (b)   TERMINATION AFTER AGE 55, BUT BEFORE AGE 60.  If Executive's
         employment is terminated after reaching age 55, but before reaching
         age 60, Executive shall be entitled to a monthly benefit, calculated
         as a single life annuity commencing as soon as practicable following
         Executive's termination from employment.  This monthly benefit shall
         equal--

         (1)  2 percent of Executive's Final Average Earnings for each of
              Executive's first 25 Years of Credited Service; minus

         (2)  0.25 percent for each month that Executive's termination date
              precedes his sixty-second birthday; plus

         (3)  3 percent of Executive's Final Average Earnings for each of
              Executive's next 5 Years of Credit Service; minus



                                       2
<PAGE>   3

         (4)  the single life annuity Executive would be entitled to under the
              Qualified Plan at the time benefits commence under this
              Agreement, minus

         (5)  the Actuarial Equivalent value (as defined in Section 7(c) below)
              of Executive's age 62 benefits under the Social Security Act.

    (c)  TERMINATION AFTER AGE 60. If Executive's employment is terminated
         after reaching age 60, Executive shall be entitled to a monthly
         benefit, calculated as a single life annuity commencing as soon as
         practicable following Executive's termination from employment.  This
         monthly benefit shall equal --

         (1)  65 percent of Executive's Final Average Earnings; minus

         (2)  the single life annuity Executive would be entitled to under the
              Qualified Plan at the time benefits commence under this
              Agreement; minus

         (3)  the Actuarial Equivalent value (as defined in Section 7(c) below)
              of Executive's age 62 benefits under the Social Security Act.

   (d)   DEFINITIONS

         (1)  CREDITED SERVICE. Executive shall be deemed to have completed 25
              Years of Credited Service at age 55. For each year of employment
              after age 55, Executive will earn one additional Year of Credited
              Service, up to a maximum of 30 years.

              If Executive terminates employment before age 55, Executive's
              Credited Service shall be determined as follows:

<TABLE>
<CAPTION>
              --------------------------------------------------------------
              AGE AT TERMINATION                  YEARS OF CREDITED SERVICE
              -------------------------------------------------------------
              <S>                                 <C>
                      51                                    21

                      52                                    22

                      53                                    23

                      54                                    24
              -------------------------------------------------------------
</TABLE>



                                       3
<PAGE>   4

            (2)  FINAL AVERAGE EARNINGS. Executive's Final Average Earnings
                 shall equal one-twelfth of Executive's "Final Average Earnings"
                 as determined under the Qualified Plan without regard to the
                 limitation on compensation described in Section 401(a)(17) of
                 the Internal Revenue Code of 1986.


   4.  CHANGE IN CONTROL BENEFIT

       (a)  ELIGIBILITY. If Executive terminates employment following a Change
            in Control for any reason other than a voluntary termination
            without Good Reason, Executive's benefit shall be determined under
            this Section 4 instead of Section 3.

       (b)  AMOUNT OF BENEFIT. The benefit payable under this Section 4 shall
            be a monthly benefit, calculated as a single life annuity
            commencing as soon as practicable following Executive's termination
            from employment. This monthly benefit shall equal the greater of --

            (1)  the benefit determined under Section 3 above as of the date of
                 Executive's termination of employment; or

            (2)  60 percent of Executive's Final Average Earnings (as defined
                 in Section 3(d)(2) above), without deduction for early
                 commencement, but with reductions for benefits payable under
                 the Qualified Plan and the Social Security Act.

       (c)  CHANGE IN CONTROL. A Change in Control means (i) the acquisition by
            any one person or entity, or by more than one person or entity
            acting as a group or in concert, of ownership of stock or securities
            of either Blue Cross or Cerulean representing 5% OR MORE of the
            voting power of any class of stock or securities of either Cerulean
            or Blue Cross (except in the case of registered common stock of
            either Blue Cross or Cerulean traded on a recognized exchange or
            through the National Association of Securities Dealers Automated
            Quotation System (NASDAQ), which may be held in excess of 5% by
            institutional investors holding for investment purposes only); (ii)
            the date on which a majority of the members of the Board of
            Directors of either Blue Cross or Cerulean are no longer "Continuing
            Directors" as that term is defined in the License Agreement between
            Cerulean and the Blue Cross and Blue Shield Association, originally
            dated February 2,1996; (iii) approval by the shareholders of
            Cerulean or Blue Cross of any merger or consolidation or statutory
            share



                                       4
<PAGE>   5
            exchange as a result of which the securities of Cerulean or Blue
            Cross shall be changed, converted or exchanged (other than a merger
            or share exchange with a controlled subsidiary of Cerulean or Blue
            Cross) into the share of the another corporation or person or the
            liquidation of Cerulean or Blue Cross or the sale or disposition of
            50% or more of the assets or earning power of either Cerulean or
            Blue Cross; (iv) approval by the shareholders of any plan of
            consolidation or merger or statutory share exchange as a result of
            which persons who were shareholders of Cerulean or Blue Cross
            immediately prior to the effective date of the plan shall thereafter
            retain less than 50% of the voting power to elect directors of the
            surviving corporation. Notwithstanding the foregoing a registered
            secondary offering shall not be deemed a change in control for
            purposes of this plan.

            The references to 5% in clause (c)(i) above shall be subject to
            review and revision by the Compensation Committee if there is any
            future revision to the provisions in the Licensing Agreement
            between the Company and Blue Cross and Blue Shield Association
            relating to a change in the voting control of the Company.

   5.  DISABILITY BENEFIT

       (a)  DISABILITY BEFORE AGE 55. If Executive terminates employment on
            account of Disability before age 55, Executive shall be entitled to
            a single life annuity commencing as soon as practicable following
            such termination from employment. This monthly benefit shall equal
            the amount determined under Section 3(b) above, assuming Executive
            had reached age 55 and completed 25 Years of Credited Service at the
            time of Disability.

       (b)  DISABILITY AFTER AGE 55. If Executive terminates employment on
            account of Disability after reaching age 55, Executive shall be
            entitled to a single life annuity commencing as soon as practicable
            following such termination from employment. This monthly benefit
            shall equal the amount determined under Section 3(b) or 3(c) above
            (whichever applies), based on Executive's actual age and Years of
            Credited Service at the time of Disability.



                                       5
<PAGE>   6

       (c)  DISABILITY. Executive shall be treated as having a Disability under
            this Agreement if he has any physical or mental condition which, in
            the opinion of the Company, prevents Executive from performing his
            duties as the Company's President and Chief Executive Officer. Any
            condition which is treated as a Disability under Executive's
            Employment Agreement shall also be treated as a Disability under
            this Agreement.  Similarly, any condition which is treated as a
            Disability under this Agreement shall also be treated as a
            Disability under Executive's Employment Agreement.

   6.  DEATH BENEFIT

       (a)  DEATH BEFORE AGE 55. If Executive dies before age 55 while actively
            employed, Executive's Beneficiary shall be entitled to a single
            life annuity commencing as soon as practicable following
            Executive's death. This monthly benefit shall equal the amount that
            would have been payable to Executive under Section 3(b) above,
            assuming that Executive had retired an the date of his death, and
            assuming that Executive had reached age 55 and completed 25 Years
            of Credited Service at the time of death.

       (b)  DEATH AFTER AGE 55. If Executive dies while actively employed after
            reaching age 55, Executive's Beneficiary shall be entitled to a
            single life annuity commencing as soon as practicable following
            Executive's death. This monthly benefit shall equal the amount that
            would have been payable to Executive under Section 3(b) or Section
            3(c) (whichever applies), assuming Executive had retired on the day
            of his death.

       (c)  BENEFICIARY. Executive may designate any person or persons to be his
            Beneficiary under this Agreement. If Executive does not designate a
            Beneficiary, or if the Beneficiary designated by Executive is not
            living at the time of his death, the Beneficiary shall be
            Executive's surviving spouse or, if there is no surviving spouse,
            Executive's estate.



                                       6
<PAGE>   7


   7.  FORM OF PAYMENT

       (a)  NORMAL FORM OF PAYMENT. Unless Executive elects an option form of
            payment under Section 7(b) below, the single life annuity
            determined under Section 3, 4, or 5 shall be converted into an
            Actuarial Equivalent lump sum payment which shall be paid to
            Executive as of the benefit commencement date described in such
            Section.

       (b)  OPTIONAL FORM OF PAYMENT. In lieu of the lump sum payment described
            in Section 7(a), Executive may elect to receive his benefit under
            this Agreement in any one of the optional forms of payment
            permitted under the Qualified Plan. However, an election is valid
            under this Section 7(b) only if it is made at least one year before
            Executive's termination from employment.

            An optional form of payment shall be the Actuarial Equivalent of
            the single life annuity calculated under Section 3, 4, or 5
            (whichever is applicable).

       (c)  ACTUARIAL EQUIVALENT. Actuarial Equivalent means a benefit having
            the same value as the benefit which it replaces, computed on the
            same basis as optional payment forms under the Qualified Plan.

   8.  FUNDING

       The Agreement is intended to constitute an unfunded plan maintained for
       a "select group of management or highly compensated employees" with the
       meaning of Section 201(2) of the Employee Retirement Income Security Act
       of 1974. However, Company shall fully and continuously fund these
       benefits through a "grantor trust" which meets the requirements of
       subpart E, part I, subchapter J, chapter 1, subtitle A of the
       Internal Revenue Code of 1986.

   9.  DISPUTE RESOLUTION

       Any dispute arising from the interpretation or application of this
       Agreement shall be submitted to final and binding arbitration. Company
       shall appoint one arbitrator and Executive shall appoint one arbitrator.
       If these two arbitrators are unable to resolve the dispute,



                                       7
<PAGE>   8

       these arbitrators will appoint a third arbitrator who will resolve the
       dispute.  The award of the arbitrators shall be final and binding upon
       the parties and judgment upon the award may be entered in any court
       having jurisdiction.

       All expenses of the arbitration process shall be borne by Company.

  10.  MISCELLANEOUS PROVISIONS

       (a)  WAIVER. The failure of either party to insist in any one or more
            instances upon performance of any terms or conditions of this
            Agreement shall not be construed as a waiver of future performance
            of any such term, covenant, or conditions. The obligations of both
            Company and Executive shall continue in full force and effect.

       (b)  SEVERABILITY. If any provision of this Agreement shall be held
            illegal or invalid, the illegality or invalidity shall not effect
            its remaining parts. The Agreement shall be construed and enforced
            as if it did not contain the illegal or invalid provision.

       (c)  ASSIGNMENT. Executive may not assign or otherwise alienate the
            benefits payable under this Agreement.

       (d)  TAX WITHHOLDING.  Company may withhold from any payment under this
            Agreement any federal, state, or local taxes required by law to be
            withheld with respect to the payment and any sum Company may
            reasonably estimate as necessary to cover any taxes for which it
            may be liable and that may be assessed with regard to the payment.

       (e)  GOVERNING LAW. This Agreement shall be governed by and construed in
            accordance with the laws of the State of Georgia.

       (f)  ENTIRE AGREEMENT. This Agreement supersedes the all previous
            agreements between Executive and Company and contains the entire
            understanding and agreement between the parties with respect to the
            subject matter hereof. This Agreement may not be amended, modified,
            supplemented, or terminated except by a subsequent written
            instrument signed by both parties.



                                       8
<PAGE>   9


IN WITNESS WHEREOF, the parties hereto have executed this Agreement on the date
and year first written above.


                                    COMPANY

                                    BLUE CROSS AND BLUE SHIELD
                                    OF GEORGIA, Inc.



                                    By /s/ James L. LaBoon, Jr.
                                       ---------------------------------------
                                       Chairman of the Board



ATTEST:


By /s/ Mitchelle D. Johnson
   ----------------------------

                                    EXECUTIVE



                                    By /s/ Richard D. Shirk
                                       ---------------------------------------
                                       Richard D. Shirk



                                       9