USA State Payroll Rates + Resources: State of Illinois: Filing State Income Taxes, W2s, and 1099s


The purpose of this documentation is to outline the processes and requirements associated with filing state income taxes as well as how to file W-2s and 1099s, if needed, in the state of Illinois.

State Income Tax Withholding 

To determine the amount of income tax withholdings, employees should fill out an IL-W-4 form. Employers are required to keep a copy of a completed IL-W-4 form for their employees in their files. The forms serve as verification that state income taxes are being withheld according to the employee’s instructions and needs to be available for inspection if the state requests it. 

Forms Federal W-4 and IL-W-4 are generally valid until the employee provides new ones. However, employees who claim exemption from withholding must renew the exemption annually by filing new Forms W-4 or IL-W-4 by February 15th each year. 


State Income Tax Withholding Reporting and Deposits

Employers can report and make Illinois tax deposits (payments) electronically by registering and using the Illinois Department of Revenue online at MyTax Illinois.

All IL-941 returns are due quarterly. All taxpayers are assigned to one of two filings and payment due dates schedules: semi-weekly or monthly.

Filing Requirements

Quarterly Filer: Form IL-941 is due by the last day of the month that follows the end of the quarter:

Quarter Months in Quarter IL-941 Due
1stJanuary, February, March
April 30th
2ndApril, May, June
July 30th
3rdJuly, August, September
October 31st
4thOctober, November, December
January 31st

Returns must be filed online through MyTax Illinois or by phone at 800-570-3329. A quarterly return must be filed even if the employer paid no wages subject to withholding, had no employees during the quarter or had not withheld tax.

W-2 and 1099 Forms 

W-2 and 1099 forms may be filed using MyTax Illinois. For more information, see the MyTax Illinois Guide for Filing Form W-2 and 1099.   

The 2019 W-2s are due on or before January 31st, 2020. Any time a due date falls on a weekend or a state-recognized holiday, the due date is moved to the next business day.

If the IRS has granted an extension of time to file federal information return due to a natural disaster or other approved reasons, an employer must submit copies of its W-2s to the Illinois Department of Revenue on or before the extended due date of the federal information return. 

Taxpayers who are granted a federal extension for information returns due on or before January 31st and who file their W-2 information on or before the federal extended due date will not be penalized. Businesses that make a reasonable and good faith effort to comply with the deadline will not be penalized.

An annual reconciliation is not required by the state of Illinois, but you can verify your records and correct errors by going to the Form IL-941 Information and Instructions

Good to Know!

A W-2c is a corrected W-2 and W-2G is a W-2 for gambling winnings.