Illinois Payroll Tax and Registration Guide

Employers in the Prairie State: learn about Illinois payroll tax and registration here.

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Account Number(s) Needed:

Companies who pay employees in Illinois must register with the IL Dept of Revenue to receive an IL Taxpayer ID (with a SEQ number) and a Security Account Number.

IL Dept of Revenue Taxpayer ID Number & Security Account Number: 99-9999999 000 (12 digits, actually the company’s EIN followed by a SEQ number)

  • Register online with the Dept of Revenue at MyTaxIllinois using the EIN to obtain a tax account number. You can also use this form.
  • Register for ACH Credit Authorization, you can find the instructions here.
  • Find an existing Taxpayer ID:

Illinois Department of Employment Security Account number: 9999999 9 (7-8 digits)

  • Register online with the Department of Employment Security at MyTaxIllinois
  • Find an existing Taxpayer ID:
    • On Form UI-340, Illinois Employer’s Contribution and Wage Reporting.
    • By contacting the IDES.

Required Payroll Documentation:


  • IL-941 (Illinois Quarterly Withholding Income Tax Return): This report is a good source of information used to balance wages and taxes withheld from prior quarters.


  • IL UI 3_40 (Employer’s Contribution and Wage Reporting): This return is a good source of information to use to balance employee gross wages paid and employer contributions made in prior quarters.

Third Party Access /POA Needed:

  • No

Local Income Taxes Imposed:  

  • No

State Resources

Visit state resources for specific tax rates and wage details:
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