Business Registration

If you plan to operate a business in Illinois, you must register with the Illinois Department of Revenue (IDOR). This resource outlines how to register online or by mail, obtain a tax ID number, and secure required business licenses.

The Illinois Department of Revenue (IDOR) provides the official channels for registering your business to meet state tax and licensing requirements. Whether you’re a sole proprietor, LLC, nonprofit, or partnership, this guide walks you through how to file Form REG-1 online via MyTax Illinois or submit it by mail. The page also outlines how to obtain your Certificate of Registration or License, maintain compliance, and update your information if your business changes. It’s a foundational step for doing business legally in Illinois, especially before making sales, hiring employees, or applying for permits.