How to File the Illinois Employer’s Contribution and Wage Report (UI-3/40)

To file the Illinois UI-3/40, log in to MyTax Illinois at mytax.illinois.gov, enter your quarterly wage totals and each employee’s wages, apply your assigned contribution rate to taxable wages (capped at $14,250 per worker for 2026), and submit the report with payment by the last day of the month after the quarter closes.¹ Employers with 25 or more workers in the prior calendar year must file electronically; smaller employers can still use paper, though most file through the portal because it handles the arithmetic.²

Quarterly Deadlines

The UI-3/40 covers one calendar quarter, and the report and payment share a single due date — the last day of the month after that quarter ends.³

January through March: due April 30
April through June: due July 31
July through September: due October 31
October through December: due January 31

Filing on time but paying late still triggers interest, so treat filing and payment as one task. If you mail a paper payment, the due date is a received-by date, not a postmark date.⁴

What to Gather Before You Log In

Have these items in front of you before opening the portal:

Your IDES account number, which appears on the Annual Contribution Rate Determination notice IDES mails each December.
Your Federal Employer Identification Number (FEIN). Electronic filing requires it.
Your contribution rate for the calendar year, from the same rate determination notice. Rates vary by employer. If quarterly total wages are under $50,000, you use the lesser of your assigned rate or 5.4%.¹
Each employee’s full legal name and Social Security number.
Total gross wages paid to each worker during the quarter, including any amounts above the taxable cap.

The 2026 taxable wage base is $14,250 per employee. Wages above that threshold for a given worker still get reported as total wages, but they do not factor into the contribution calculation.¹

Filling In the Summary Section

The top of the form (Lines 1 through 7) calculates what you owe. MyTax Illinois populates most of these automatically once you enter the wage detail, but the logic is the same whether you file on paper or online.¹

Line 1 — Number of covered workers. Count every full-time and part-time employee who worked or was paid during the pay period that includes the 12th of each month in the quarter. Include workers already above the $14,250 wage cap and those on vacation or paid sick leave. Do not count workers on strike.

Line 2 — Total wages paid. Enter all wages paid during the quarter for covered employment, including wages paid to employees who have already earned more than $14,250 for the year.

Line 3 — Excess wages. Enter the portion of Line 2 above $14,250 per worker for the calendar year. Only count the excess earned this quarter; do not carry over excess reported in earlier quarters.

Line 4 — Taxable wages. Subtract Line 3 from Line 2.

Line 5A or 5B — Contribution due. Multiply taxable wages by your contribution rate. Use Line 5A when quarterly total wages are under $50,000 and apply the lesser of your rate or 5.4%. Use Line 5B when quarterly total wages are $50,000 or more and apply your assigned rate.

Lines 6A through 6D. Add interest on Line 6A and the late-filing penalty on Line 6B if applicable. Enter any previous underpayment on Line 6C or credit from a prior overpayment on Line 6D.

Line 7 — Total payment due. Add Lines 5A or 5B, 6A, 6B, and 6C, then subtract Line 6D.

Listing Each Employee

Below the summary, the form has a wage detail block. Enter one line per employee who received wages during the quarter:¹

Column 8: Social Security number.
Column 9: Worker’s full name.
Column 10: Total wages paid to that worker during the quarter.
Column 11: Taxable wages for that worker, capped at $14,250 for the calendar year and accounting for wages already reported in prior quarters.

An owner, partner, corporate officer, or authorized agent must sign the report. Anyone else signing needs a power of attorney on file with IDES.

Submitting the Report and Paying

Once the summary and wage detail look right, submit the report through MyTax Illinois. The portal returns a confirmation with a unique transaction ID; save it as proof of timely filing.⁴

Payment runs through the same portal. ACH debit from a checking or savings account is free. You can also mail a check or money order, but send it early enough to arrive by the deadline. The portal retains your historical submissions and payments, which is useful for audits or internal review.

If You File or Pay Late

Interest and penalties are self-assessed on the form itself.

Unpaid contributions accrue interest at 2% per month, calculated at a daily rate of 12/365 of 2% (roughly 0.066% per day). For the first 30 days past due, IDES computes interest day by day. After 30 days, payments are treated as received on the last day of the month before IDES actually gets them, which can push your effective interest period higher than expected. The Director of IDES can waive some or all of the interest for good cause.⁵

The late-filing penalty is $5 for every $10,000 (or fraction) of total wages reported, or $2,500 per month, whichever is less. That doubles to $10 per $10,000 of total wages or $5,000, whichever is less. The minimum penalty is $50 regardless of payroll size.¹ Interest goes on Line 6A and the penalty on Line 6B.

Fixing an Error on a Report You Already Filed

To correct wages, a misspelled name, or a wrong Social Security number on a submitted UI-3/40, file Form UI-40C, the Employer’s Correction Report. Use a separate UI-40C for each quarter that needs fixing.⁶ The form has two schedules:

Schedule A shows totals as originally reported and what they should be — total wages, excess wages, taxable wages, and contribution due. Complete this for every correction.
Schedule B lists only the individual workers whose wages need to change. Skip workers whose data was correct.

Include a written explanation of why the correction is needed. The same signature rules apply.

Quarters With No Payroll and Closing the Account

Once your business is liable, you must file every quarter — even quarters when you had no employees or paid no wages. A zero-wage report tells IDES the business is still active but had no taxable payroll. Skipping it triggers the same late-filing penalties as a missed report with wages.¹

If you permanently stop employing workers in Illinois, close the UI account through MyTax Illinois or by submitting Form UI-50, Notice of Change. File any outstanding UI-3/40 reports for quarters before the closure date. Until you formally close the account, IDES expects a report every quarter.²

1
Illinois Department of Employment Security. UI-3/40 Illinois Employer’s Contribution and Wage Report
2
Illinois Department of Employment Security. Employer Tax Information
3
Illinois Department of Employment Security. Quarterly Filing Requirements
4
Illinois Department of Employment Security. MyTax Illinois Employers
5
Illinois General Assembly. 820 ILCS 405/1401
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Illinois Department of Employment Security. UI-40C Employer’s Correction Report