<PAGE>
                                                                   EXHIBIT 10.43


                                  March 8, 2005

Mr. Lonnie J. Hardin

      Re:   Additional Compensation Arrangements

Dear Tim:

      I am pleased to advise You that in recognition and consideration of your
service to the ProxyMed, Inc. (the "Company") the Board of Directors of the
Company has approved several amendments to your current compensation plan. This
letter will confirm our agreement to amend your current Employment Agreement
with the Company ("Agreement"), as discussed herein.

  1.  Retention Bonus. In the event of a combination (including a tender
offer, merger, sale or exchange of 50% or more of the outstanding capital stock
of the Company, or sale of all or substantially all of its assets or otherwise)
of the Company with another party or a recapitalization of the Company or
similar restructuring (a "Strategic Transaction"), You will be eligible to
receive a lump sum bonus payment ("Retention Bonus") from the Company in the
amount of $100,000. This Retention Bonus will be due and payable in cash upon
the closing of a definitive transaction ("Closing"), or in the case of a
transaction involving a tender offer or other purchase or sale of stock, when
control of 50% or more of the Company's outstanding common stock is acquired by
an entity other than a current stockholder. In order to qualify for the
Retention Bonus, You must remain an active employee through the time of the
Closing (other than termination of your employment by the Company Without
Cause), and cooperate fully with the Company in the completion of the Strategic
Transaction. You should expect that in almost all situations, this bonus will be
fully taxable, and consult with your tax adviser for your situation. The
Retention Bonus set forth in this paragraph is in lieu of and supersedes any
prior arrangement between You and the Company with respect to a bonus payable
upon a merger, reorganization or change of control of the Company or other
Strategic Transaction, including the Merger/Buyout Bonus plan approved by the
Compensation Committee of the Company on January 23, 2002 (the "Existing Bonus
Plan"). All bonuses previously granted by the Company to You pursuant to the
Existing Bonus Plan are hereby cancelled and terminated.
<PAGE>

                                                          ProxyMed - Page 2 of 2

   2. Special Bonus. In respect of your personal efforts on behalf of the
Company during fiscal year 2004, You will receive a one time bonus of $10,000.
This bonus is in lieu of any other bonus for 2004 performance (other than any
applicable sales commission plan) will be payable in the next regular pay cycle
following the Company's public release of earnings on March 16, 2005.

   3. Salary. Effective January 1, 2005, you will receive an increase in your
base salary of $10,000. You will receive a lump sum payment in the next regular
pay cycle to cover retroactive increased compensation for the period between the
date of this letter and January 1, 2005.

   Kindly indicate Your agreement and acceptance of the terms of this bonus
letter by executing below, and returning a fully executed copy of this letter to
me at the address above.

                                            Very truly yours,

                                            PROXYMED, INC.

                                            /s/ David Edward Oles

                                            David Edward Oles
                                            Senior Vice President & Secretary

By signing below, You accept and agree as stated above:

      /s/ Lonnie J. Hardin
----------------------------

cc:   Kevin M. McNamara, CEO