How to Fill Out and Submit Illinois Form REG-1: Schedules, Filing, and Tax Types

Illinois Form REG-1, the Illinois Business Registration Application, is filed with the Illinois Department of Revenue to open a state tax account before you start doing business. The fastest way to file it is online through MyTax Illinois at mytax.illinois.gov, which processes applications in about one to two business days; a mailed paper form takes six to eight weeks.¹ There is no filing fee.

Do You Actually Need to File REG-1?

Illinois law makes it unlawful to sell tangible personal property at retail in the state without a Certificate of Registration from the Department of Revenue.² You need REG-1 if any of these describe your business:

You sell, lease, or rent tangible personal property to Illinois customers, including through vending machines.
You are an out-of-state seller whose Illinois sales reach $100,000 in gross receipts or 200 separate transactions in a year.³
You pay wages to employees working in Illinois or to Illinois residents and need to withhold state income tax.
You deal in cigarettes, tobacco, liquor, motor fuel, aviation fuel, or dry-cleaning solvents.
You provide electricity, natural gas, telecommunications, or water and sewer services in the state.
You rent hotel rooms for fewer than 30 days or lease vehicles.
You operate a medical cannabis cultivation center or dispensing organization.

One boundary worth knowing: if you sell exclusively through a marketplace like Amazon or Etsy, the marketplace facilitator collects and remits Illinois retailers’ occupation tax on those sales, not you.⁴ But the moment you make a sale outside that marketplace, such as through your own website or at a trade show, you need to be registered.

What to Gather Before You Start

Pull all of this together before you open the form or the portal. A missing item will stall you, and that hurts most on a paper filing that already takes weeks.

Your Federal Employer Identification Number. Partnerships, corporations, LLCs, trusts, and estates all need one. A sole proprietor without an FEIN files under their Social Security Number.⁵
Your legal entity name exactly as it appears in federal records, plus any DBA or assumed name you operate under.
The date you began, or will begin, doing business in Illinois. This date starts your tax clock.
The principal business address and every other Illinois location where you sell, lease, or store inventory.
Owner and officer details. Corporations need the name, title, and Social Security Number of each officer. LLCs need the same for every manager and member. Publicly traded corporations report the names and titles of the Chief Financial Officer, Chief Operating Officer, and anyone responsible for preparing tax returns.²
Your responsible party. This is the person who will sign returns and be accountable for paying the tax. The form requires their name, address, and a signed acceptance of that responsibility.
A clear description of what you sell or what services you provide.
The number of vending machines you operate, if any. The statute requires it.

Working Through the Form

Entity Type and Identification

The first section asks for your organizational structure: sole proprietorship, partnership, corporation, LLC, trust, estate, or government entity. This choice drives which owner and officer fields apply later and how the Department classifies your account. Enter your FEIN (or SSN) and your legal business name exactly as they appear on your federal filings. Any mismatch with your IRS records can cause processing delays.

Owners, Officers, and the Responsible Party

The form spends real space on who stands behind the business. Sole proprietors list themselves. Partnerships list each partner. Corporations list every officer with title, address, and Social Security Number. This is more than bookkeeping. Under Illinois law, the individuals named as responsible for filing returns and paying taxes can be held personally accountable for unpaid tax debt. The person signing the acceptance-of-responsibility statement should know what they are signing. If you run out of room on the main form, use Schedule REG-1-O for additional owners or officers and Schedule REG-1-R for responsible party details.⁶

Choosing Your Tax Types

This is where you tell the state which taxes apply. Most first-time filers check at least one of these:

Sales and use tax, if you sell, lease, or rent tangible personal property. If you also transfer property as part of a service (a repair shop installing parts, for instance), register under service occupation tax as well.
Employer withholding, if you have Illinois employees. You will also complete and attach Schedule REG-UI-1 for unemployment insurance liability.⁵
Out-of-state sales to Illinois customers, if you are a remote seller meeting the economic nexus threshold.
Marketplace facilitator, if you operate a platform that facilitates third-party sales to Illinois buyers. Attach Schedule REG-1-MKP.

Businesses in cigarettes, tobacco, liquor, motor fuel, dry cleaning, or medical cannabis each have their own checkboxes with corresponding schedules. Liquor requires Schedule REG-1-A; cigarette or tobacco registration requires Schedule REG-1-C.⁶

Fiscal Year and Business Description

Select the fiscal year you use for federal tax purposes. Most small businesses use the calendar year. If your entity uses a different fiscal year end, enter that month. Then describe your business activities with enough specificity for the Department to assign the right tax categories. “Retail” is too vague. “Online sales of custom pet accessories” tells the state what it needs to know.

Schedules You May Need to Attach

REG-1 is really a packet. Depending on your tax-type selections, you may need to include one or more of these:

Schedule REG-1-L: Illinois Business Site Location Information, for multiple physical locations.
Schedule REG-1-O: Owner and Officer Information.
Schedule REG-1-R: Responsible Party Information.
Schedule REG-1-A: Liquor Information.
Schedule REG-1-C: Cigarette and Tobacco Products Information.
Schedule REG-1-D: Electricity Tax Self-Assessing Purchaser.
Schedule REG-1-G: Gas Use Tax Self-Assessing Purchaser.
Schedule REG-1-T: Telecommunications Tax Location Information.
Schedule REG-1-MC: Medical Cannabis Cultivation Center and Dispensing Organization Information.
Schedule REG-1-MKP: Marketplace Facilitator Information.
Schedule REG-UI-1: Report to Determine Liability Under the Unemployment Insurance Act.

All of these are posted on the Department’s forms page alongside the main application.⁶ If you register online, the MyTax Illinois portal prompts you for the equivalent information inside the application flow, so you don’t need to download separate schedule PDFs.

How to Submit

Online Through MyTax Illinois

The Department strongly prefers online filing. Go to mytax.illinois.gov, click “Register a New Business (Form REG-1)” on the homepage, and work through the application.⁷ The portal flags incomplete fields before you can submit. You will get a confirmation email once processing is done, and the next day you can create a MyTax Illinois logon to manage the account. Online processing takes roughly one to two business days, and your tax Account ID or License Number arrives by email within that window.⁸

Paper Filing by Mail

If you prefer paper, download the form and all applicable schedules, complete them, and mail everything to:

Central Registration Division
Illinois Department of Revenue
PO Box 19030
Springfield, IL 62794-9030⁸

Paper applications take six to eight weeks.¹ If you need to start collecting sales tax soon, filing online is the only practical choice.

What Happens After You Register

Once the Department processes your application, you receive a Certificate of Registration. Online filers typically get the certificate and Account ID electronically within two weeks. Paper filers should expect the certificate by mail within the six-to-eight-week window.¹

Display the certificate at your place of business. The Department uses the contact information from your application to send tax filing notices, so update your account through MyTax Illinois if your address, responsible party, or business structure changes. Your filing frequency for sales tax and withholding returns, whether monthly, quarterly, or annually, will be assigned based on your expected tax liability.

What Happens if You Skip Registration

Selling tangible personal property at retail in Illinois without a Certificate of Registration is a criminal offense. Under the Retailers’ Occupation Tax Act, doing business after a registration has been revoked is a Class A misdemeanor, and each day of operation counts as a separate offense.⁹ On top of that, the Department may require a security deposit of up to three times your estimated average monthly tax liability before issuing a certificate to applicants it considers a collection risk.²

Responsible parties don’t escape liability if the business closes or falls behind. Sales tax collected from customers is treated as money held in trust for the state. If the business fails to remit it, the Department can pursue the responsible party personally for the unpaid amount. Getting the registration right at the start, and filing on time afterward, is the simplest way to stay out of that position.

1
Illinois Department of Revenue. How Soon After I Register My Business Will I Be Issued a Certificate of Registration or License
2
FindLaw. Illinois Statutes Chapter 35 Revenue 120/2a
3
Illinois Department of Revenue. Sales and Use Taxes
4
Cornell Law Institute. Illinois Administrative Code tit 86, 131.145 – Marketplace Facilitators
5
Illinois Department of Revenue. REG-1 Illinois Business Registration Application
6
Illinois Department of Revenue. Business Registration Forms
7
Illinois Department of Revenue. What Is MyTax Illinois and How Do I Access It
8
Illinois Department of Revenue. Business Registration
9
Illinois General Assembly. 35 ILCS 120/13