Updated September 7, 2023
What we'll cover
- What information OnPay needs from you
- What state and local taxes and filings OnPay handles for Illinois employers
- Where you can find the tax account numbers needed
- Paying employees in other states?
Why is this important?
For employers who pay employees in Illinois, the state will require state income tax. Use this guide to learn what’s required to start running payroll while keeping compliant with state payroll tax regulations. Click on the topic below to learn more.
What information OnPay needs from you
Use this checklist to make sure you’ve covered everything required to set up your account as an Illinois employer so OnPay can accurately file and pay taxes on your behalf:
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✔ |
To do: |
What is this? |
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Make sure your business is registered with the Illinois Department of Revenue |
Allows your business to file and pay taxes in Illinois |
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Make sure your business is registered with the Department of Employment Security |
Allows your business to pay required unemployment insurance in Illinois |
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Provide OnPay with your Illinois State Withholding Tax ID and deposit schedule |
The employer identification number issued by the Illinois Department of Revenue |
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Provide OnPay with your Illinois Unemployment ID |
A number unique to your account with the Illinois Department of Employment Security |
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Provide OnPay with your Illinois Unemployment (SUI) Rate |
A tax rate you receive annually from the Department of Employment Security |
What state and local taxes and filings OnPay handles for Illinois employers
OnPay handles the filing of all state and local taxes for businesses in Illinois, including:
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Type of Tax |
Form ID |
Form Name |
Frequency |
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Withholding |
Form IL-501 |
Semi-Weekly or Monthly Withholding Payment |
Semi-weekly or monthly |
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Form IL-941& Schedule P |
Quarterly Withholding Reconciliation |
Quarterly |
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State W2 (Filing) |
Wage and Tax Statement |
Annual |
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Unemployment |
IDES Form UI-3/40 |
Illinois Quarterly Tax and Wage Report |
Quarterly |
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Other |
New Hire Report (Filing) |
Illinois New Hire Reporting Form |
As required |
Where you can find the tax account numbers needed
If you are an existing employer who has previously run payroll in Illinois, you likely already have the IDs and online accounts needed for OnPay to process your tax filings.
If you are a new employer in Illinois, you will need to register your business with the Illinois Department of Revenue and the Illinois Department of Employment Security. This must be completed for OnPay to be able to file and pay your Illinois taxes.
Withholding Tax Account Number
Existing Illinois Employer:
This account number will include your Federal EIN, and you can find the ID on your Illinois Withholding Income Tax Return (IL-941).
New Illinois Employer: Register with the Illinois Department of Revenue
- Electronically register through MyTax Illinois (approximately one to two days to process)
- Complete and mail Form REG-1, Illinois Business Registration Application, to the address on the form (Form REG-1 is also available on their website as a fillable form).
- Registration forms are also available by calling the Department of Revenue at 1-800 356-6302.
- You'll be able to register using your Federal EIN. Your account number will include your Federal EIN.
Existing Illinois Employer:
- Your Unemployment account number and your Illinois UI Contribution Rate will be on the Notice of Contribution Rate that you receive from the Illinois Department of Employment Security (IDES) each year.
- Your Unemployment Tax Rate can be found in the far contribution rate box of the Tax Rate Notice. New employers generally have a rate of 3.95% for SUTA with a wage base of $13,271.
New Illinois Employer: Register with the Department of Employment Security
- Register your business with the IL Department of Employment Security.
- You'll instantly be issued an Unemployment Account Number in the format of Example: 1234567-8 or 1234567. It is important to note that your unemployment tax number is NOT the same as your FEIN. The last digit of your Unemployment number is called the check digit and the department will often omit it from correspondence. If you don't receive your Unemployment ID, please call the agency at (800)247-4984 to request it.
Paying employees in other states?
If you operate in multiple states or just have employees working from home across a state line, it's important to file the correct state forms for those workers. See what forms we file in the states where you pay employees.
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