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Illinois

Register your new business in Illinois with this comprehensive step-by-step guide.

Illinois - New Business Registration Guide

State Tax Agencies

  • Illinois Department of Revenue (IDOR) – State Income Tax Withholding
  • Illinois Department of Employment Security (IDES) – Unemployment Insurance (UI) Tax

Types of Tax

  • State Income Tax Withholding
  • State Unemployment Insurance (UI) Tax

Step-by-Step Registration Process

1. Gather Required Information

Before starting, make sure you have the following:

  • Federal Employer Identification Number (FEIN)
  • Legal business name and entity type (LLC, Corporation, etc.)
  • Physical business address
  • Responsible party/contact for payroll taxes
  • Ownership structure and officer/member information

2. Register Online via MyTax Illinois

A. Create a MyTax Illinois Account

  • Click “Register a New Business (Form REG-1)”
  • Enter your FEIN and complete the business details
  • Submit the registration form online

Processing Time: Typically 1–2 business days

B. Select Applicable Tax Types

During registration, be sure to select:

  • State Income Tax Withholding
  • Unemployment Insurance (UI) Tax

This ensures both your Taxpayer ID (IDOR) and Unemployment Account Number (IDES) are assigned through a single application.

C. Activate Your Online Account

  • After submission, you’ll receive a confirmation screen and an authentication code by email
  • Use this code to activate your MyTax Illinois user account
  • All tax types under your FEIN or SSN will be linked to your MyTax Illinois profile

3. Alternative Registration Methods (Optional)

If not registering online, you may register:

  • By Mail
    • Submit Form REG-1 to IDOR
    • Submit Form UI-1 to IDES
  • In Person
    • Visit a local Illinois Department of Revenue office

Processing Time for Paper Forms: 4–6 weeks

Grant Third-Party Access to Check

To authorize filing on your behalf:

  • Navigate to Settings → Manage Third Party Access
  • Set the following:
    • Allow = Yes
    • Default Access = Third Party
    • Default Account Access = Full Access

Contact Information

  • IDOR (Withholding): (217) 785-3707 or REV.DoNotReply@Illinois.gov
  • IDES (UI Tax): (800) 247-4984

This guide does not contain legal or tax advice. If legal or tax advice is required, an attorney, CPA or tax adviser should be consulted.

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Last updated on March 31, 2024

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