Form IL-1120-ST-V, designated as the Payment Voucher for Small Business Corporation Replacement Tax by the Illinois Department of Revenue, is the standardized remittance document used by Subchapter S corporations to submit physical tax payments. Unlike standard C corporations that pay both corporate income and replacement taxes, S corporations in Illinois are subject to a personal property replacement tax assessed on net business earnings allocable to the state. When an entity does not utilize the state electronic tax system, Form IL-1120-ST-V serves as the essential tracking slip that accompanies physical checks or money orders. The form captures critical identifying information, including the company federal employer identification number, accounting year details, primary contact figures, and the exact payment sum. Submitting this voucher alongside your remittance guarantees that state processing systems credit payments promptly and accurately to your business account, preventing misallocated funds, billing notices, late payment penalties, and statutory interest accrual.
How To File Form IL-1120-ST-V
Filing Form IL-1120-ST-V involves straightforward document preparation, careful attention to payment formatting, and adherence to mailing instructions.
When To Use And When To Skip This Form
You should only submit Form IL-1120-ST-V if your S corporation owes a balance and you choose to remit that balance by mail using a paper check or money order. Do not file this form under any of the following circumstances:
- Your corporation has zero tax liability due for the tax period.
- You are claiming a tax refund or carrying forward an overpayment.
- You submit your tax payment electronically through the state tax portal or automated clearinghouse channels.
- The state tax department has officially mandated that your business submit all tax remittances through electronic payment options.
If you are paying by mail, you must use Form IL-1120-ST-V for all types of paper payments associated with Form IL-1120-ST, including estimated quarterly tax installments, tentative payments submitted with automatic filing extension requests, passthrough entity tax remittances, advance prepayments, or final return balances due.
Mailing Guidelines And Submission Addresses
The proper mailing address depends on whether you are mailing the voucher by itself or attaching it to an original paper tax return.
If you are submitting your annual tax return by mail at the same time, staple your completed voucher and check directly to the front page of your tax return, and send the entire package to the filing address specified in the main return instructions.
If you are submitting a standalone payment—such as an estimated installment, an extension payment, or an advance payment submitted separately from your tax return—mail the voucher and check to:
Illinois Department of Revenue
P.O. Box 19053
Springfield, IL 62794-9053
Payment Preparation Guidelines
To ensure your physical check or money order clears without administrative delay, follow these payment standards:
- Make the check or money order payable to the Illinois Department of Revenue.
- Write your nine-digit Federal Employer Identification Number clearly on the memo line of your payment.
- Write the tax year ending date (month and year) on the payment instrument.
- Write the form designation IL-1120-ST-V directly on the front of the check or money order.
- Enter payment figures in whole dollars only, rounding off fractional cents.
How To Complete Form IL-1120-ST-V
Form IL-1120-ST-V consists of a concise single-tier voucher layout designed for automated scanning. Complete every field accurately using black ink or standard digital entry before printing and detaching the voucher.
Business Identification Details
FEIN
Enter the nine-digit Federal Employer Identification Number issued to your S corporation by the Internal Revenue Service. Do not include hyphens or dashes.
Name
Write the full legal business name of the S corporation exactly as registered with the Illinois Secretary of State and reported on federal Form 1120-S.
C/O
Enter the name of the individual, corporate officer, legal representative, or accounting firm designated to receive official correspondence, if applicable. If not applicable, leave this space blank.
Mailing Address
Provide the complete postal mailing address for the business, including the street address, suite or unit number, or post office box.
City
Enter the city associated with your corporate mailing address.
State
Provide the standard two-letter state postal abbreviation for the business address.
ZIP
Record the complete five-digit postal zip code or the nine-digit extended routing code.
Phone
Enter the daytime telephone number, including the three-digit area code, where an authorized company officer or representative can be contacted regarding account questions.
Tax Period And Payment Computation
Tax Year Ending Month
Enter the two-digit numerical designation (01 through 12) for the calendar month in which your corporation’s tax year concludes. For example, a calendar-year corporation would enter 12.
Tax Year Ending Year
Provide the four-digit calendar year in which the tax accounting period ends.
Payment Amount
Enter the exact dollar amount of the check or money order submitted with this voucher. Enter whole dollar figures only, rounding down cents under 50 and rounding up amounts of 50 to 99 cents.
Final Review Before Filing
Before mailing your completed payment voucher to the Illinois Department of Revenue, verify the following items:
- Check that the nine-digit FEIN matches your federal corporate tax return and state tax registration records.
- Confirm that the ending month and year correspond precisely to the specific tax period for which the payment is intended.
- Verify that the payment amount on the voucher matches the exact dollar sum written on your check or money order.
- Ensure that the payment instrument is made payable to the Illinois Department of Revenue and includes your FEIN, tax period ending date, and the designation IL-1120-ST-V on the memo line.
- Confirm that you are not mailing this voucher if you already submitted or scheduled your payment electronically through the state online portal.
- Make sure to separate the completed voucher slip cleanly from the instructional page prior to enclosing it in the mailing envelope.