Illinois Employer Registration: IDOR Withholding, IDES Unemployment, New Hire Reporting and Workers' Comp

Illinois employer registration happens in three places at once: a withholding account with the Illinois Department of Revenue (IDOR), an unemployment insurance account with the Illinois Department of Employment Security (IDES), and a workers' compensation policy from an insurer. All three are opened before or immediately after the first paycheck, and the state expects a new hire report for every employee. This guide covers who registers, how, the 2026 rates, and the filing dates ahead, with notes for owners whose home-country payroll rules in Canada or India work differently.

Who needs Illinois employer registration?

Any business that pays wages to employees working in Illinois, including a single-owner LLC that pays one part-time worker. A sole proprietor or a partnership is itself an employer once it hires someone. IDOR's rules cover anyone required to withhold federal income tax on compensation paid in Illinois; IDES covers any employing unit that is liable for unemployment contributions, and it even requires a report when no contribution is due. Household employers who pay $1,000 or more in cash wages in a calendar quarter are also employers for unemployment purposes.

How do you register, step by step?

1. Get the federal EIN from the IRS. It is free; see Illinois business startup steps.
2. Open MyTax Illinois at mytax.illinois.gov and choose "Register a New Business (Form REG-1)". Online registrations take roughly one to two business days; paper applications take weeks. Register before you make purchases or sales or hire.
3. Register for IDES unemployment insurance. The same MyTax Illinois session can cover it, or you can file paper form REG-UI-1, the Report to Determine Liability. The deadline is 30 days from start-up.
4. Choose payment methods. Withholding payments are made electronically or with Form IL-501; IL-941 returns and W-2s are filed electronically unless IDOR grants a waiver.
5. Buy workers' compensation insurance before the first employee works.
6. Set up new hire reporting with IDES (online account, or the IDES New Hire form by fax or mail).
7. Complete federal onboarding: Form W-4, Form I-9 and federal deposits, covered in the U.S. employer compliance checklist.
8. Put the filing dates on the calendar (see below and the Illinois compliance calendar). Return to the How to Do Business hub for related registrations.

How does Illinois withholding work?

You withhold Illinois income tax from employee wages by using the IL-700-T tables and the allowances on the employee's Illinois W-4 (IL-W-4). As the withholding agent you are liable for tax you were required to withhold even if you failed to collect it from the employee. Payment schedules:

All Form IL-941 returns are due quarterly, whichever payment schedule you use. IDOR requires W-2, W-2c and W-2G reporting electronically, and IL-941 electronically, unless a waiver is approved. For the full explanation see Illinois payroll, withholding, UI and new hire.

How does IDES unemployment insurance work?

IDES taxes employers on the first slice of each worker's annual pay. For 2026, IDES reports:

• Taxable wage base: $14,250 per worker per calendar year.
• Standard new employer rate: 3.350%, which includes a 0.550% fund-building rate; employers in NAICS sector 56 start at 3.450%.
• Range for experienced employers: minimum 0.750%, maximum 7.050%, using a 2026 state experience factor of 102%.
• Small quarterly payrolls: an employer whose quarterly wages are under $50,000 and whose rate exceeds 5.400% pays 5.400% for that quarter.

Quarterly Form UI-3/40 reports are due April 30, July 31, October 31 and January 31. Employers with 25 or more employees in the prior calendar year must file electronically and also submit monthly wage reports for the first and second months of each quarter. Quarterly extensions of 30 days and monthly extensions of 15 days may be requested before the due date.

How do you report new hires?

All employers must report new employees to the state New Hire Directory within 20 days of the employee's first day on the payroll. IDES runs the directory in Illinois, so the report goes through its portal or the IDES New Hire form. The directory exists to support child support enforcement.

What are the workers' compensation rules?

Illinois requires workers' compensation insurance for almost everyone hired in, injured in or localized to Illinois, even one part-time worker. Sole proprietors, partners, bona fide corporate officers and LLC members may choose to opt out, except in extra-hazardous work such as construction and trucking. An employer that knowingly and willfully fails to insure may be fined up to $500 per day with a $10,000 minimum, and up to $1,000 per day with a $20,000 minimum for repeat noncompliance; corporate officers can be personally liable, and the employee may sue in civil court.

What are the next deadlines?

The IDOR dates come from its 2026 Publication 131-D, which adjusts for weekends and holidays. IDES lists the statutory dates; filing before a weekend avoids doubt.

Worked example

Neha opens a dental billing office in Naperville (see our Naperville guide) and hires her first employee on Monday, November 9, 2026, at $6,000 gross for the rest of 2026. She registered in MyTax Illinois on November 2, so her IDOR and IDES accounts are open before the hire. The new hire report is due within 20 days, by November 29. Her estimated 2026 Illinois UI contribution at the standard 3.350% rate is about $201 on the $6,000 of wages (all below the $14,250 base). She bought a workers' compensation policy effective November 9, and her first IL-941 and UI-3/40 are due in early 2027 under the dates above.

How do Canada and India compare?

Canadian employers register a payroll account with the CRA and remit source deductions, usually monthly; Indian employers deduct tax at source and make provident fund and insurance contributions. Illinois splits the same tasks across IDOR, IDES and a private insurer. The payroll filing comparison puts the three systems side by side.

Mistakes to avoid

• Waiting for the first payroll before registering with IDES.
• Treating an owner who also works as exempt from workers' compensation without a written election.
• Missing the 20-day new hire report for part-time or seasonal workers.
• Filing IL-941 on a prior year's form; the form is year-specific.
• Mixing the monthly and semi-weekly schedules after a quarter above $12,000.

How we can help

Our firm is based in the Aurora area and handles payroll set-up, IDOR and IDES registrations, quarterly returns and year-end W-2 filing for Illinois employers, and we coordinate with your Canadian CPA or Indian Chartered Accountant when owners also run payroll abroad. See payroll and employer compliance.

Frequently asked questions

General information only. It is not tax, legal, accounting or immigration advice for your situation, and rules change; confirm the current rules with the official source or a licensed professional in the relevant country.