Illinois Payroll Tax and Registration Guide

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)

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:

Withholding 

  • 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. 

Unemployment

  • 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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