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                                                                 Exhibit 10.12.3
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December 29, 1998

Mr. Brad Mullinax
Chief Financial Officer
Acsys, Inc.
75 14th Street
Suite 2200
Atlanta, GA 30309

Dear Brad:

Per your request, NationsBank, N.A., as Agent and as Lender, has agreed to amend
the definition of "Total Revolving Credit Commitment" contained in the Revolving
Credit Agreement dated May 16, 1997 as amended by Amendment No. 1 to the Credit
Agreement dated June 29, 1998 and Amendment No. 2 to the Credit Agreement dated
August 3, 1998 ("Amendment No. 2") by and among ACSYS, Inc. (formerly known as
ICCE, Inc.), as Borrower, NationsBank, National Association, as Agent and the
Lenders party thereto (the "Credit Agreement"), effective as of the date of
acceptance and agreement indicated below, so that as amended it reads as
follows:

"Total Revolving Credit Commitment" means (a) through April 30, 1999 a principal
amount equal to $40,000,000 and (b) at all times thereafter a principal amount
equal to $25,000,000, in each case as reduced from time to time in accordance
with Section 2.07."

NationsBank, N.A. as Agent and as Lender, hereby waives the resulting Default or
Event of Default, if any, under (i) Section 8.01 of the Credit Agreement for the
Four-Quarter Period ending December 31, 1998 so long as the Consolidated
Leverage Ratio does not exceed 3.50 to 1.00 for such Four-Quarter Period, and
(ii) Section 8.02 of the Credit Agreement for the Four-Quarter Period ending
December 31, 1998 so long as the Consolidated Fixed Charge Coverage Ratio is not
less than 1.25 to 1.00 for such Four-Quarter Period.

This amendment and waiver shall not be deemed to be a waiver or amendment of any
other term or condition of the Credit Agreement, Notes or other Loan Documents.
The terms and conditions of sections 3, 5, and 7 through 12 of Amendment No. 2
are repeated, reaffirmed and incorporated herein by reference and applicable to
the amendment and waiver set forth above as if originally included in this
letter agreement. Capitalized terms used but not otherwise defined herein shall
have the meanings ascribed to such terms in the Credit Agreement.

The Guarantors have joined in the execution of this letter agreement for the
purposes of consenting hereto and for the further purpose of confirming their
guaranty of the Obligations of the Borrower as provided in the Guaranty
Agreement. Without limiting the generality of the foregoing, each Guarantor
acknowledges the increase in the amount of the Obligations as a result of the
terms of this letter agreement.
<PAGE>
 
ACSYS, Inc.
Total Revolving Credit Commitment Letter
December 29, 1998
Page 2

Sincerely,

NATIONSBANK, N.A., as
Agent and as Lender

By:
   -------------------------
Name: Barbara P. Levy
Title: Senior Vice President

Accepted and Agreed to
As of            , 1998
     ------------

ACSYS, Inc.

By:
   -------------------------
Name: Brad Mullinax
Title: Chief Financial Officer

GUARANTORS:

DAVID C. COOPER AND ASSOCIATES, INC.

By: 
   -------------------------
Name:
Title:

ACSYS FINANCIAL STAFFING, INC.

By:
   -------------------------
Name: 
Title:

EKT, INC.

By: 
   -------------------------
Name: 
Title:

INFINITY ENTERPRISES, INC.

By: 
   -------------------------
Name: 
Title:
<PAGE>
 
ACSYS, Inc.
Total Revolving Credit Commitment Letter
December 29, 1998
Page 3

CAMA OF TAMPA, INC.

By:
   -------------------------
Name:
Title:

ACSYS RESOURCES, INC.

By:
   -------------------------
Name:
Title:

C.P.A. STAFFING, INC.

By:
   -------------------------
Name:
Title:

RYLAN FORBES CONSULTING GROUP, INC.

By:
   -------------------------
Name:
Title:

ICON SEARCH & CONSULTING, INC.

By:
   -------------------------
Name:
Title:

DRAMONDI, INC.

By:
   -------------------------
Name:
Title:

AI INVESTMENTS, INC.

By:
   -------------------------
Name:
Title: