What Is the Illinois REG-1 Form?
- The REG-1 is the official business registration form used by the Illinois Department of Revenue (IDOR).
- It’s how businesses register to collect sales tax, pay employee withholding, and report other state taxes.
Why Businesses Need to File REG-1
- Illinois law requires any business selling taxable goods or services, hiring employees, or leasing property in the state to register with the IDOR.
- Filing ensures you’re set up to collect and remit the right taxes from day one—avoid penalties later.
Who Needs to File the REG-1?
- Brick-and-mortar shops in Illinois.
- Online sellers shipping to Illinois customers (economic nexus rules apply if you exceed $100K in sales or 200+ transactions in the state).
- Remote businesses with employees or contractors located in Illinois.
- Freelancers and consultants doing business under a trade name.
- Landlords renting commercial property in Illinois.
What Taxes Does REG-1 Apply To?
- Sales and Use Tax – If you sell physical products or certain digital goods.
- Withholding Tax – If you have employees and need to withhold state income tax.
- Telecommunications, Hotel Operators, Liquor, or Cannabis Tax – Industry-specific options appear during registration.
- Use Tax – If you’re buying equipment or inventory out of state.
Step-by-Step: How to File the REG-1 Online
- Step 1: Go to https://mytax.illinois.gov
- Step 2: Click “Register a New Business” (you don’t need an account yet).
- Step 3: Enter your EIN (or SSN for sole proprietors), legal business name, and DBA (if applicable).
- Step 4: Provide your start date for sales, payroll, or business operations in Illinois.
- Step 5: Choose which taxes you’ll be responsible for.
- Step 6: Add info for each location where you operate in Illinois (even if remote).
- Step 7: Review everything and hit submit—you’ll get a confirmation screen and a reference number.
After You Register
- Within a few business days, the IDOR will mail you a Certificate of Registration and your Illinois Account ID.
- You’ll also get instructions on how to start filing and paying taxes through MyTax Illinois.
Common Mistakes to Avoid
- Picking the wrong tax types—read each section carefully and don’t over-register.
- Skipping locations—each warehouse, store, or office in IL must be listed.
- Using different names than your IRS documents—this creates processing delays.
Need to Register By Paper?
- While online filing is fastest, you can also download and print the REG-1 PDF from the IDOR website.
- Mail it to the address listed at the bottom of the form—but expect slower processing.
Where to File the REG-1
👉 MyTax Illinois: https://mytax.illinois.gov
👉 Paper version (PDF): REG-1 Form on IDOR site