Illinois Form IL-W-4 — Employee’s and Other Payee’s Illinois Withholding Allowance Certificate

Get the blank Form IL-W-4 (PDF)  ·  Checked line by line against the official Illinois form, last verified September 8, 2026  ·  How we verify

What is Form IL-W-4?

Form IL-W-4 is Illinois’s employee withholding allowance certificate. Illinois income tax is withheld from your wages at the flat state rate, and the amount of income treated as exempt from that withholding depends on the number of allowances you claim on this form. More allowances mean less tax withheld; fewer allowances, or an extra dollar amount on Line 3, mean more.

The form has three parts: instructions, a worksheet that figures your basic and additional allowances, and the detachable certificate you sign and hand to your employer. It also lets you claim complete exemption from Illinois withholding if you qualify. Completing it correctly matters because too many allowances can leave you underwithheld and facing a penalty, while the reciprocal-state and high-income rules change which allowances you may claim.

Who Must Complete Illinois Form IL-W-4?

Employees. If you are an employee, you complete IL-W-4 so your employer withholds the correct Illinois income tax. If you do not file one, fail to sign it, omit required information, or alter it, your employer must withhold on your entire pay with no allowances.

Payees with voluntary withholding. You may complete IL-W-4 and give it to a payer if you have arranged voluntary Illinois withholding on non-wage Illinois income.

People claiming exempt status. If you expect to owe no Illinois income tax, you may check the exempt box, sign and date the certificate, and leave Lines 1–3 blank. Your employer must disregard an exempt claim if you have not also filed a federal Form W-4 claiming total exemption.

Who uses a different form. Residents of Iowa, Kentucky, Michigan, and Wisconsin, and qualifying military spouses, use Form IL-W-5-NR to establish that their Illinois wages are not subject to Illinois withholding.

How to File Illinois Form IL-W-4

• Complete the worksheet on the back of the form to figure your allowances, and keep it for your records.
• Fill in the certificate with your basic allowances (Line 1), additional allowances (Line 2), and any extra dollar amount (Line 3), or check the exempt box.
• Sign and date it, and give it to your employer. Do not send it to the Illinois Department of Revenue. Your employer keeps it and may be required to send it to the Department for inspection.
• Multiple jobs: For the most accurate withholding, claim all your allowances on the IL-W-4 for your highest-paying job and claim zero on the others.

Before you start, have your federal Form W-4 Deductions Worksheet (if you completed one), and know whether anyone can claim you as a dependent and whether you or your spouse are 65 or older or legally blind.

When to Submit Illinois Form IL-W-4

• On or before your first day of work, or whenever Illinois income tax first has to be withheld from your pay.
• When your allowances increase (for example, a new dependent), you may file a new form — this is optional.
• When your allowances decrease, you must file a new form within 10 days.
• Effective date: If you have no IL-W-4 on file with the employer, the new form applies to your first payment after you file it. If you already have one on file, the employer may apply a change immediately but is not required to until the first payment after the first day of the next calendar quarter (January 1, April 1, July 1, or October 1) that is at least 30 days after you file the change.
• Death of a spouse or dependent does not change your allowances until the next tax year.
• How long it lasts: Your IL-W-4 stays in effect until a newer one takes effect or the employer is required by the Department to disregard it.

Where to Send Illinois Form IL-W-4

You do not mail IL-W-4 to the state. Give the signed certificate to your employer (or to the payer, for voluntary non-wage withholding). Keep the worksheet yourself.

• Employer’s role: Keep the certificate with payroll records. The employer must disregard an exempt claim not backed by a federal W-4 claiming exemption, or a federal W-4 the IRS has told them to disregard, and may be required to send your IL-W-4 to the Illinois Department of Revenue for inspection.
• No electronic filing with the state. Your employer may offer an electronic equivalent through its payroll system.
• For help, contact the Illinois Department of Revenue at 1-800-732-8866 or 217-782-3336, TDD 1-800-544-5304, or write to Illinois Department of Revenue, PO Box 19044, Springfield, IL 62794-9044.

How to Complete Illinois Form IL-W-4 Line by Line

Withholding Allowance Worksheet — Step 1: Basic personal allowances

Check boxes — “No one else can claim me as a dependent” and “I can claim my spouse as a dependent”: Check each that applies to you.

Line 1: Enter the number of those boxes you checked.

Line 2: Enter the number of dependents, other than you or your spouse, you will claim on your tax return.

Line 3: Add Lines 1 and 2. This is the total number of basic personal allowances you are entitled to.

Line 4: Enter the number of basic allowances you choose to claim, up to Line 3 (you may claim as few as zero). Carry this to Line 1 of the certificate. A lower number here means more tax withheld.

Worksheet — Step 2: Additional allowances

Check boxes — you or your spouse age 65 or older, you or your spouse legally blind: Check each that applies.

Line 5: Enter the number of those boxes you checked.

Line 6: Enter any amount from Line 4 of the federal Form W-4 Deductions Worksheet, plus any additional Illinois subtractions or deductions.

Line 7: Divide Line 6 by 1,000 and round to the nearest whole number.

Line 8: Add Lines 5 and 7. This is the total number of additional allowances you are entitled to.

Line 9: Enter the number of additional allowances you choose to claim, up to Line 8 (as few as zero). Carry this to Line 2 of the certificate.

The Certificate

Social Security number, name, street address, city, state, ZIP: Enter your identifying information.

Exempt box: Check it only if you are exempt from both federal and Illinois income tax withholding, then sign and date and leave Lines 1–3 blank.

Line 1: Enter the total basic allowances you are claiming, from worksheet Step 1, Line 4.

Line 2: Enter the total additional allowances you are claiming, from worksheet Step 2, Line 9.

Line 3: Enter any additional flat dollar amount you want withheld from each paycheck, on top of the amount your allowances produce.

Signature and date: Sign to certify that you are entitled to the allowances claimed, and date the certificate.

Common Mistakes to Avoid

• Claiming more allowances than the worksheet supports. Lines 1 and 2 of the certificate cannot exceed worksheet Lines 4 and 9.
• Checking exempt without a federal exemption. Your employer must ignore an Illinois exempt claim unless you also filed a federal W-4 claiming total exemption.
• Not filing a new form within 10 days of a decrease in allowances. This is required, not optional.
• Splitting allowances across jobs. Claim all allowances on the highest-paying job’s IL-W-4 and zero on the others.
• Using IL-W-4 as an Iowa, Kentucky, Michigan, or Wisconsin resident. Use Form IL-W-5-NR instead.
• Ignoring non-wage income. Interest, dividends, and side income can leave you underwithheld even with correct allowances — use Line 3 or make estimated payments.
• Sending it to the state. IL-W-4 goes to your employer.
• Leaving it unsigned. An unsigned certificate is treated as if no form was filed.

Frequently Asked Questions

Do I have to fill out IL-W-4? Yes, if you are an Illinois employee. Without a completed, signed form your employer withholds with no allowances.

How many allowances should I claim? As many as the worksheet supports for the most accurate withholding, or fewer if you want a larger refund or have other untaxed income.

Can I claim exempt from Illinois withholding? Only if you expect to owe no Illinois income tax and you have also claimed total exemption on your federal W-4. Check the exempt box and sign.

When does a change take effect? Immediately if you have no form on file; otherwise no later than the first payment after the first day of the next quarter that is at least 30 days after you file the change.

I got married / had a baby. Do I have to file a new form? Not immediately — filing when allowances increase is optional. You must file within 10 days only when allowances decrease.

I live in Wisconsin and work in Illinois. Which form? File Form IL-W-5-NR with your employer; IL-W-4 does not apply to your reciprocal-state wages.

Where do I send IL-W-4? To your employer. Keep the worksheet for your own records.

Can I have extra tax withheld? Yes. Enter a flat dollar amount on Line 3 of the certificate.

Final Review Before Submitting

• The worksheet is complete and kept for your records.
• Certificate Line 1 does not exceed worksheet Step 1, Line 4.
• Certificate Line 2 does not exceed worksheet Step 2, Line 9.
• Any extra withholding amount is on Line 3.
• If claiming exempt, the box is checked, Lines 1–3 are blank, and you have a federal W-4 claiming exemption.
• You are not a resident of Iowa, Kentucky, Michigan, or Wisconsin (those use IL-W-5-NR).
• The certificate is signed and dated.
• The certificate is given to your employer, and the worksheet is kept by you.
• You have a reminder to file a new form within 10 days if your allowances ever decrease.

General information from the official form and its instructions, not advice for your circumstances. See the full disclaimer.