Illinois REG-1 Business Registration explains how Business Owners and Employers register with the Illinois Department of Revenue using Form REG-1 to obtain state tax accounts and operate legally in Illinois.
This guide covers Who needs to register, How To apply online or by mail, required schedules, FEIN requirements, and next steps after registration.
1. Overview of Illinois REG-1 Business Registration
Form REG-1 is the Illinois Business Registration Application used to open tax accounts with the Illinois Department of Revenue (IDOR).
Registration is required for entities that conduct business in Illinois or sell to Illinois customers and for those with tax responsibilities administered by IDOR.
What Is Form REG-1?
Form REG-1 collects business information to establish your Illinois taxpayer ID and any applicable tax accounts.
The application asks for business name, address, Federal Employer Identification Number, type of entity, and the types of taxes you will collect or remit.
How To Apply For Form REG-1
Online registration through MyTax Illinois is the fastest option and typically processes in one to two business days.
To register online go to MyTax Illinois and choose "Register a New Business (Form REG-1)." Follow the prompts and submit electronic signatures where required.
If you prefer paper, download Form REG-1 from the IDOR website, complete it, and mail it to the address shown on the form.
Paper applications generally take four to six weeks to process, so allow extra time before you begin operations.
You can also register in person at an IDOR office and staff can assist you with completing Form REG-1 if you need help.
2. Who Needs To Register
You must register if your Business sells taxable goods or services in Illinois.
Register if you Withhold Illinois Income Tax for employees or are liable for other taxes IDOR administers, such as excise taxes.
Certain exceptions apply for occasional sellers or small volume activities; contact IDOR's Central Registration Division for specific guidance.
For assistance call 217-785-3707 or email [email protected] if you are unsure whether your Business must register.
Exceptions and Nexus Considerations
Some remote sellers or service providers may qualify for thresholds or exemptions under Illinois law and should confirm registration requirements with IDOR.
Maintain documentation of sales and nexus determinations to support any claim of exemption or threshold-based non-registration.
3. Additional Schedules and Required Information
Depending on your Business activities you may need to submit one or more REG-1 schedules with your application.
Common schedules include REG-1-A for Liquor Information, REG-1-C for Cigarette and Tobacco Products, REG-1-L for Business Site Location Information, and REG-1-O for Owner and Officer Information.
Including all applicable schedules and accurate FEIN information reduces processing delays and follow up from IDOR.
Federal Employer Identification Number (FEIN)
Obtain a FEIN from the IRS before registering if your Business has employees or operates as a corporation or partnership.
The FEIN is used on Form REG-1 to link your federal tax identity to your Illinois accounts.
4. After Registration: What To Expect
Once processed IDOR will issue a Certificate of Registration or License and assign your Illinois taxpayer ID number.
Certificates for many tax types are issued electronically and are accessible and printable through MyTax Illinois.
If you cannot print an electronic certificate contact the Central Registration Division to request a paper copy.
Timing and Notifications
Online applicants usually receive confirmations within a couple business days while mailed applicants should expect several weeks.
Keep copies of the confirmation and taxpayer ID for Payroll and filing systems when you begin collecting or remitting taxes.
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5. Updating Registration Information
Update registration promptly when business details change such as address, ownership, new locations, or additional tax responsibilities.
Updates can be made electronically through MyTax Illinois, by calling 217-785-3707, or in person at an IDOR office.
6. Employer Responsibilities and Unemployment Insurance
If you have employees register for Unemployment Insurance with the Illinois Department of Employment Security (IDES).
New Employer registration for unemployment tax can be done through MyTax Illinois or by submitting Form REG-UI-1 to IDES.
Keep accurate records of employee wages, withholdings, and employer account numbers to ensure timely filings and payments.
7. Quick Reference Table of Accounts and Agencies
| Account Type | Agency | How To Register |
|---|---|---|
| Federal FEIN | Internal Revenue Service | Apply online at the IRS EIN application before registering with IDOR |
| Illinois REG-1 (State Tax Account) | Illinois Department of Revenue | Register online via MyTax Illinois or mail Form REG-1; online processing 1-2 business days |
| Withholding Tax Account | Illinois Department of Revenue | Obtain through REG-1; report payroll and withhold Illinois Income Tax for employees |
| Unemployment Insurance | Illinois Department of Employment Security | Register online via MyTax Illinois or submit Form REG-UI-1 to IDES |
| Industry Schedules (Liquor, Tobacco, Site Info) | Illinois Department of Revenue | Include REG-1 schedules such as REG-1-A, REG-1-C, REG-1-L, REG-1-O with your application |
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8. Additional Resources For Registration and Forms
- Illinois Department of Revenue - Business Registration
- MyTax Illinois
- Form REG-1 - Illinois Business Registration Application
- Illinois Department of Employment Security - New Employer Registration
- IRS - Apply for an Employer Identification Number (EIN) Online
Illinois REG-1 Business Registration: Conclusion
Registering with IDOR using Form REG-1 is a critical step for Illinois Business Owners and Employers who sell taxable goods, withhold state income tax, or owe other state taxes.
Use MyTax Illinois for the fastest processing, include all applicable schedules, obtain your FEIN early, and register with IDES if you hire employees to stay compliant with Illinois requirements.
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