Illinois payroll tax and registration guide

  • Updated

Why is this important?

To maintain compliance with state payroll tax regulations, you must provide the following information before you can use OnPay to run payroll:

  • State Employer Identification Number and state/local tax IDs
  • Tax rates - State tax offices set these rates based on the type, age, and size of your business
  • TPA and power of attorney - Most tax offices require this before we can submit quarterly wage reports and deposits on your behalf

This information must be provided and maintained by you in order for OnPay to accurately file and deposit tax payments for your company. OnPay is not responsible for any penalties or interest that incur due to missing or incorrect company tax information.

Each state has its own requirements, so if you pay employees in more than one state, you’ll find separate tax guides for each state.

Let Middesk handle your state tax registrations

Want help registering your business with state agencies? We've partnered with Middesk to make it simple for you to stay compliant in your state — and every state — when hiring employees.

  • Register with state agencies and get the tax IDs you need within minutes
  • Manage all your government accounts in one place using Middesk's intuitive platform
  • Stay compliant by managing agency mail and notices from your Middesk dashboard
  • Foreign Qualify with the Secretary of State to create payroll tax accounts 

Learn more about Middesk

 

See what information you need to provide OnPay, and what taxes and filings OnPay handles for Illinois Employers.

  • Information OnPay needs from you

    Use this checklist to make sure you’ve covered everything required to set up your account as a Illinois employer, so OnPay can accurately file and pay taxes on your behalf:

    All Illinois employers What is this?
    Make sure your business is registered with the Illinois Department of Revenue

    Allows your business to file and pay taxes in Illinois

    More info >

    Make sure your business is registered with the Department of Employment Security

    Allows your business to pay required unemployment insurance in Illinois

    More info >

    Provide OnPay with your Illinois State Withholding Tax ID and deposit schedule

    The employer identification number issued by the Illinois Department of Revenue

    More info >

    Provide OnPay with your Illinois Unemployment ID

    A number unique to your account with the Illinois Department of Employment Security

    More info >

    Provide OnPay with your Illinois Unemployment (SUI) Rate

    A tax rate you receive annually from the Department of Employment Security
    More info >

  • Taxes and filings OnPay handles for Illinois Employers

    Withholding Tax

    Form IL-501

    Semi-Weekly or Monthly Withholding Payment - Semi-weekly or monthly

    Form IL-941 & Schedule P

    Quarterly Withholding Reconciliation

    - Quarterly

    State W-2 (Filing)

    Wage and Tax Statement

    - Annual

    Unemployment Insurance Tax

    IDES Form UI-3/40

    Illinois Quarterly Tax and Wage Report

    - Quarterly

    Other

    New Hire Report (Filing)

    Illinois New Hire Reporting Form

    - As required


Where you can find the tax account numbers you need

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

 

Unemployment Tax Account Number and contribution rate

Updated January 1, 2025

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 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.
  • New employers generally have a rate of 3.65% for SUTA with a wage base of $13,916.

 

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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