Substitute Form IL-1040-ES Vendor 

                                               Specifications

Prepare each IL-1040-ES form with the following information:                                      
               (1)   Software/Forms Developer ID Number
               (2)   Primary’s Social Security Number (SSN)
               (3)   Primary SSN Check Digit (See detailed instructions below.)
               (4)   Taxpayers’ Post -  The first four letters of the taxpayer’s last name.
               (5)   Spouse’s SSN
               (6)   Spouse SSN Check Digit (See detailed instructions below.)
               (7)   Taxpayer’s Name and Address
               (8)   Amount of Payment. The payment amount field must show dollars and two positions for cents.            
                     If the payment is a whole dollar amount, zero fill the cents field to the right of the dollar amount.
               (9)   Daytime Phone Number
       (10)          Scan Line (See detailed instructions below.)
       (11)          Barcode (See detailed instructions on the following page.)

SSN Check Digit Formula
The check digit is figured from the following calculations.
EXAMPLE: SSN = 0 0 0 3 4 7 6 3 1
Step 1:  Beginning at the left most digit, multiply each digit of the SSN alternating by 2 and then 1.
                    0        0       0         3       4      7  6  3          1
            X        2       1       2         1       2      1  2  1          2
                 =   0       0       0         3       8      7  12 3          2
Step 2: Add any two digit number in the products together to obtain one digit. (12 = 1 + 2 = )3
Step 3:  Add the Step 1 products together substituting the one-digit number found in Step 2 for the two-digit number.   
               0 + 0 + 0 + 3 + 8 + 7 + 3 + 3 + 2 = 26. 
Step 4: Determine the unit (ones) position of the result of Step 3. The unit position of 26 is 6. 
Step 5: If the result of Step 4 is zero, then zero is the check digit. Otherwise, subtract the unit position from 10.  For   
               the example, 10 - 6 = 4.  4 is the check digit.
 
Scan Line Placement and Contents 
The scan line must be centered horizontally on the page (the center of the scan line must be at 4.25 inches) and 
must fall between .25 and .375 inches from the bottom edge of the form. There must be only the scan line in the 
bottom .5 inch of the form. 
Contents: The scan line contains 39 positions as described below. The font for the scan line is “OCR-A Std”, size 10.
   Positions within the scan line:
       1  Voucher Number is always 1
       2  Space
 3 - 11  Primary’s SSN 
     12  Space 
     13   Primary SSN Check Digit (See formula above.)
     14  Space 
  15 - 22  Numeric Post  (See formula on next page.)
     23  Space
  24 - 32  Spouse’s SSN
     33   Space
     34  Spouse SSN Check Digit (See formula above.)
     35  Space 
  36 - 39  Account Period Ending (APE). Fill with the last month and year of the tax year being paid (mmyy). 
           Example: December 2024 is 1224.         Use the same APE for each estimated payment for the account.

                                                   Printed by the authority of the State of Illinois, Web only - 1 copy IL-1040-ES SPECS (R-12/23)

                       Substitute Form IL-1040-ES Vendor 

                                              Specifications
                                              (continued from Page 1)

Numeric Post Formula 
Determine the numeric post from the first four letters of taxpayer’s last name. The numeric post is calculated by number-
ing the alphabet from 01 - 26 beginning with the letter A as 01, B as 02, and so on. 

Numeric post examples and special rules:  
                 For a last name Joneket = JONE = the numeric post is 10151405
                 For a last name that is less than four characters, fill each ending space with 00. 
                       Last name of Coe = COE = the numeric post is 03150500
                 For a last name containing an apostrophe or hypen, omit the punctuation.
                       Last name of O’Connor = OCON = the numeric post is 15031514 
                 For a last name containing a space, omit the space.  
                       Last name of De Von  = DEVO = the numeric post is 04052215

1-D Barcode
1-D Barcode font is “Free 3 of 9 Extended”, size 30 pt (height around 5/16 inch), and the content is *60312241V*. There 
must be at least 1/4 inch quiet zone (white space) around the barcode. 

Important: Electronic payments are required if the taxpayer’s previous year’s annual liability was $200,000 or 
more.

                                    Substitute forms producers:  This form 
                                    must be reproduced with preprinted 
                                    information, including a scan line. 
                                    Please see instructions and example 
                                    on Pages 3 and 4.

          Illinois Department of Revenue                      
                                               ID: 123(1)
          IL-1040-ES  2024                                          
                                                                                                       Official Use
          Estimated Income Tax Payment for Individuals                                            
Enter your Social Security numbers in the order they appear on your federal return.                    Calendar-Year Taxpayers
                                (3)      (4)
                       (2)   *4*    JONE      000-34-8787(5)                        *3*(6)   Your estimated tax payments are due on 
  000-34-7631
Your Social Security number                 Spouse’s Social Security number                    April 15, 2024     September 16, 2024
                                                                                               June 17, 2024      January 15, 2025
 
                                    (7)                                                                (8)
   John and    Annie Joneket                                                               $ 
                                                                                                              500     00
          1234 Folks Place                                                                  Amount of payment (Whole dollars.only)
   Anywhere            IL  12345-1234          example                                      Make check payable and mail this voucher to: 
                                                                                            ILLINOIS DEPARTMENT OF REVENUE 
  (555)123-1234(9)                                                                          SPRINGFIELD IL 62736-0001
IL-1040-ES (R-12/23)                (11)      *60312241V*

                                (10)
                                    1 000347631 4 10151405 000348787 3 1224